WTNT44 KNHC 141433
TCDAT4
TROPICAL STORM DEAN DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 AM EDT TUE AUG 14 2007
 
SATELLITE IMAGES...MICROWAVE DATA AND QUIKSCAT MEASUREMENTS INDICATE
THAT THE DEPRESSION HAS REACHED TROPICAL STORM STATUS AND ALSO THAT
THE CENTER IS LOCATED FARTHER TO THE SOUTH AND WEST THAN PREVIOUSLY
INDICATED. DEAN HAS DEVELOPED A SMALL CENTRAL DENSE OVERCAST OVER
THE CENTER BUT MOST OF THE CONVECTION IS STILL LOCATED TO THE WEST
AND SOUTH OF THE CENTER. THE OUTFLOW IS CONFINED TO THE WEST AND
SOUTHWEST SINCE THE CYCLONE IS STILL EMBEDDED WITHIN EASTERLY
SHEAR. THE SHEAR IS FORECAST TO DECREASE AND MOST OF THE INTENSITY
GUIDANCE GRADUALLY STRENGTHENS DEAN. IN FACT...DYNAMICAL GUIDANCE
SUGGESTS THAT DEAN COULD BE NEAR THE LESSER ANTILLES AS A HURRICANE
WITH 100 TO 110 KNOTS IN FIVE DAYS. 

DEAN APPEARS TO BE MOVING WESTWARD OR 265 DEGREES AT 20 KNOTS AROUND
THE PERIPHERY OF A STRONG SUBTROPICAL RIDGE WHICH IS EXPANDING
WESTWARD. IN THE SHORT TERM...2 TO 3 DAYS...DEAN SHOULD CONTINUE TO
MOVE ON A GENERAL WESTWARD TRACK WITH A GRADUAL DECREASE IN FORWARD
SPEED. THEREAFTER...THE FORECAST BECOMES HIGHLY UNCERTAIN SINCE
SOME RELIABLE MODELS MAINTAIN A STRONG RIDGE TO THE NORTH AND KEEP
THE CYCLONE MOVING WESTWARD ACROSS THE CARIBBEAN AND OTHERS SHOW A
WEAKER RIDGE RESULTING IN A GRADUAL TURN TO THE WEST-NORTHWEST. THE
OFFICIAL FORECAST FOLLOWS THE CONSENSUS AND IS A LITTLE BIT TO THE
SOUTH OF THE PREVIOUS ONE...DUE TO THE REPOSITIONING OF THE
CENTER...AND NOT BECAUSE WE HAVE CHANGED THE FORECAST REASONING.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/1500Z 11.7N  39.4W    35 KT
 12HR VT     15/0000Z 11.8N  42.0W    40 KT
 24HR VT     15/1200Z 11.8N  45.6W    45 KT
 36HR VT     16/0000Z 11.8N  48.5W    50 KT
 48HR VT     16/1200Z 12.0N  51.5W    60 KT
 72HR VT     17/1200Z 13.5N  56.5W    70 KT
 96HR VT     18/1200Z 15.5N  61.0W    80 KT
120HR VT     19/1200Z 17.5N  65.0W    95 KT
 
$$
FORECASTER AVILA
 

WTNT44 KNHC 142053
TCDAT4
TROPICAL STORM DEAN DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT TUE AUG 14 2007
 
DEAN'S STRUCTURE HAS NOT IMPROVED DURING THE AFTERNOON. CONVECTION
HAS WANED AND REMAINS ESPECIALLY LIMITED IN THE NORTHEASTERN
SEMICIRCLE...THOUGH THIS MAY BE A DIURNAL FLUCTUATION. BOTH TAFB
AND SAB GAVE DVORAK ESTIMATES OF T2.5 OR 35 KT...WHILE AN AMSU PASS
AT 1623 UTC SUGGESTED A SUBSTANTIALLY STRONGER INTENSITY. GIVEN THE
LACK OF CONVECTIVE VIGOR...THE INTENSITY OF DEAN IS KEPT AT 35 KT.

INITIAL MOTION OF DEAN IS 265 DEGREES AT 18 KT...A BIT SLOWER THAN
THE LAST ADVISORY.  DEAN IS SOUTH OF A DEEP-LAYERED RIDGE WHICH
SHOULD STEER THE CYCLONE TOWARD THE WEST OR WEST-NORTHWEST FOR THE
NEXT FEW DAYS.  THE MODEL GUIDANCE SHIFTED SOMEWHAT TO THE WEST AND
FASTER COMPARED TO THE 06 UTC RUNS...PERHAPS DUE TO A WEAKER AND
LESS DIGGING TROUGH OFF OF THE U.S. EAST COAST BY DAY 5.  THE
OFFICIAL TRACK FORECAST IS TO THE LEFT OF AND FASTER THAN THE
PREVIOUS ADVISORY...BUT REMAINS TO THE RIGHT OF THE CONSENSUS OF
THE GFS...GFDL...AND HWRF.  COMPARED TO THE OTHER MODELS...TRACK
SOLUTIONS FOR THE NOGAPS AND ECMWF ARE SLOWER BECAUSE THEY DO NOT
APPEAR TO HAVE A GOOD HANDLE ON DEAN'S FAST INITIAL FORWARD SPEED.

DEAN IS CURRENTLY EXPERIENCING MODERATE NORTHEASTERLY SHEAR...IS
OVER 27.5C SSTS...AND IS WITHIN A MOIST ENVIRONMENT.  THE SHEAR
SHOULD DROP WHILE THE SSTS WARM OVER THE NEXT FEW DAYS...SO THE
ENVIRONMENT APPEARS TO BE CONDUCIVE FOR GRADUAL INTENSIFICATION. 
THE INTENSITY FORECAST IS CLOSE A CONSENSUS OF THE HWRF...
GFDL...SHIPS...AND LGEM THROUGH 72 HR.  THEREAFTER...THE INTENSITY
FORECAST RELIES PRIMARILY UPON THE GFDL AND LGEM MODELS.  BY DAY
5...DEAN IS FORECAST TO BE A STRENGTHENING HURRICANE AND COULD
REACH MAJOR HURRICANE STATUS BY THEN.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      14/2100Z 11.6N  41.0W    35 KT
 12HR VT     15/0600Z 11.7N  43.6W    40 KT
 24HR VT     15/1800Z 12.0N  46.9W    45 KT
 36HR VT     16/0600Z 12.3N  50.2W    50 KT
 48HR VT     16/1800Z 12.6N  53.5W    60 KT
 72HR VT     17/1800Z 14.0N  59.5W    70 KT
 96HR VT     18/1800Z 15.5N  64.5W    85 KT
120HR VT     19/1800Z 17.5N  69.5W    95 KT
 
$$
FORECASTER LANDSEA/KNABB
 

WTNT44 KNHC 150254
TCDAT4
TROPICAL STORM DEAN DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT TUE AUG 14 2007
 
AFTER THE CONVECTION WANED THIS AFTERNOON...A NEW BURST HAS
REDEVELOPED OVER THE CENTER DURING THE PAST FEW HOURS. DESPITE THE
SOMEWHAT RAGGED SATELLITE APPEARANCE AROUND 2100 UTC...A QUIKSCAT
PASS AT THAT TIME DETECTED A RATHER WELL DEFINED CIRCULATION WITH
BELIEVABLE 45-50 KT WINDS. WITH A NOD TO THE SATELLITE
PRESENTATION...THE INITIAL INTENSITY IS SET AT A POSSIBLY
CONSERVATIVE 45 KT. RECENT MICROWAVE IMAGERY AND THE QUIKSCAT DATA
SUGGEST THAT THE CENTER IS SLIGHTLY NORTH OF THE EARLIER ESTIMATES. 

THE INITIAL MOTION IS 270/16...A LITTLE SLOWER THAN THE PREVIOUS
ADVISORY.  THE FORECAST PHILOSOPHY REMAINS UNCHANGED AS DEAN IS
EXPECTED TO BE STEERED WEST TO WEST-NORTHWESTWARD DURING THE NEXT
FEW DAYS...SOUTH OF A DEEP-LAYER RIDGE.  THE MODEL GUIDANCE
GENERALLY AGREES ON THIS SCENARIO BUT WITH SOMEWHAT VARYING FORWARD
SPEEDS.  THE OFFICIAL TRACK FORECAST REMAINS FASTER THAN THE NOGAPS
AND ECMWF SOLUTIONS...WHICH CONTINUE TO STRUGGLE INITIALIZING THE
FORWARD MOTION OF DEAN. THE NEW TRACK FORECAST IS CLOSER TO THE
CONSENSUS OF THE GFDL...HWRF AND GFS MODELS THROUGH 72 HOURS...BUT
IS A LITTLE SLOWER THAN THESE MODELS AT DAYS 4 AND 5.

IT APPEARS THAT THE EASTERLY SHEAR THAT HAS BEEN AFFECTING DEAN IS
BEGINNING TO DECREASE.  THE GLOBAL MODELS FORECAST A FAVORABLE
ENVIRONMENT FOR STEADY STRENGTHENING AND THE AVAILABLE INTENSITY
GUIDANCE BRINGS DEAN TO A HURRICANE IN 36-48 HOURS...AND NEAR THE
MAJOR HURRICANE THRESHOLD BY DAY 5.  

THE WIND RADII WERE ADJUSTED BASED ON THE QUIKSCAT DATA.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/0300Z 12.0N  42.3W    45 KT
 12HR VT     15/1200Z 12.2N  44.8W    50 KT
 24HR VT     16/0000Z 12.4N  48.2W    55 KT
 36HR VT     16/1200Z 12.8N  51.7W    60 KT
 48HR VT     17/0000Z 13.4N  55.2W    70 KT
 72HR VT     18/0000Z 14.5N  61.0W    80 KT
 96HR VT     19/0000Z 16.0N  66.5W    90 KT
120HR VT     20/0000Z 17.5N  71.5W   100 KT
 
$$
FORECASTER BROWN
 

WTNT44 KNHC 150832
TCDAT4
TROPICAL STORM DEAN DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 AM EDT WED AUG 15 2007
 
THE CENTRAL CONVECTION ASSOCIATED WITH DEAN HAS MORE OF A BANDED
APPEARANCE THIS MORNING...ALTHOUGH THE BANDING IS NOT YET
WELL-DEFINED.  WHILE VERTICAL WIND SHEAR HAS DECREASED...IT MAY BE
THAT A COMBINATION OF DRY AIR SEEN IN WATER VAPOR IMAGERY NEAR THE
STORM AND INFLOW FROM OVER THE COOLER WATERS TO THE NORTH ARE
SLOWING AN INCREASE IN CONVECTIVE ORGANIZATION.  THE INITIAL
INTENSITY REMAINS 45 KT BASED ON CONTINUITY FROM THE EARLIER
QUIKSCAT DATA AND THE PREVIOUS ADVISORY.

THE INITIAL MOTION IS A SLIGHTLY UNCERTAIN 275/16...UNCERTAIN DUE TO
AMSU MICROWAVE DATA HINTING THAT THE CENTER IS A LITTLE SOUTH OF
THE ADVISORY POSITION.  WATER VAPOR IMAGERY INDICATES THAT DEAN IS
ON THE SOUTH SIDE OF A DEEP-LAYER RIDGE... WITH A LARGE
MID/UPPER-LEVEL TROUGH COVERING THE ATLANTIC AND CARIBBEAN BETWEEN
64W-77W.  THE LARGE-SCALE MODELS SUGGEST THAT THE TROUGH SHOULD
GRADUALLY FILL DURING THE FORECAST PERIOD...WITH RIDGING PERSISTING
NORTH OF DEAN.  THIS SHOULD RESULT IN A GENERAL WESTWARD TO
WEST-NORTHWESTWARD MOTION.  THERE HAVE BEEN SOME CHANGES IN THE
MODEL GUIDANCE...AS THE CANADIAN AND ECMWF MODELS HAVE SHIFTED FROM
A WEST-NORTHWESTWARD TRACK TOWARD THE BAHAMAS TO A MORE WESTWARD
MOTION THROUGH THE CARIBBEAN.  THE UKMET CONTINUES TO CALL FOR A
GENERAL WESTWARD MOTION...WHILE THE GFS CALLS FOR A WEST-
NORTHWESTWARD MOTION NEAR THE END OF THE FORECAST PERIOD.  THE
NEW FORECAST TRACK IS SIMILAR TO THE PREVIOUS TRACK THROUGH 72
HR...THEN SHIFTED A LITTLE WEST OF THE PREVIOUS TRACK THEREAFTER
BASED ON THE OVERALL CHANGE IN THE ENVELOPE OF GUIDANCE.  THE NEW
TRACK IS IN BEST AGREEMENT WITH...BUT A LITTLE SLOWER THAN...THE
GFS.

DEAN SHOULD ENCOUNTER WARMER SEA SURFACE TEMPERATURES ALONG THE
FORECAST TRACK...AND THE VERTICAL SHEAR IS FORECAST TO BE LIGHT
DURING THE FORECAST PERIOD.  THE INTENSITY GUIDANCE CALLS FOR
STEADY STRENGTHENING...AND SO DOES THE INTENSITY FORECAST IN BEST
AGREEMENT WITH THE ICON CONSENSUS.  GIVEN THE FAVORABLE UPPER-LEVEL
WINDS AND WARM WATER...THERE IS A POSSIBILITY THAT DEAN COULD BE
NOTABLY STRONGER THAN FORECAST BY THE END OF THE FORECAST PERIOD.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/0900Z 12.2N  44.2W    45 KT
 12HR VT     15/1800Z 12.4N  46.6W    50 KT
 24HR VT     16/0600Z 12.8N  50.1W    55 KT
 36HR VT     16/1800Z 13.2N  53.7W    60 KT
 48HR VT     17/0600Z 13.8N  57.1W    70 KT
 72HR VT     18/0600Z 15.0N  63.0W    80 KT
 96HR VT     19/0600Z 16.0N  68.5W    90 KT
120HR VT     20/0600Z 17.5N  74.0W   100 KT
 
$$
FORECASTER BEVEN
 

WTNT44 KNHC 151435
TCDAT4
TROPICAL STORM DEAN DISCUSSION NUMBER   9
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 AM EDT WED AUG 15 2007

SATELLITE IMAGES INDICATE THAT DEAN HAS A SMALL CENTRAL DENSE
OVERCAST CLOUD PATTERN.  HINTS OF A BANDING EYE HAVE BEEN SEEN ON
VISIBLE AND MICROWAVE IMAGERY...AND SATELLITE INTENSITY ESTIMATES
HAVE BEEN INCREASING.  THE CURRENT INTENSITY ESTIMATE OF 50 KT IS A
BLEND OF TAFB/SAB SUBJECTIVE DVORAK ESTIMATES OF 45 KT AND AMSU/AODT
ESTIMATES OF NEAR 55 KT.

THE INITIAL MOTION IS ABOUT THE SAME AS BEFORE...275/17. A STRONG
DEEP-LAYERED RIDGE LIES TO THE NORTH OF DEAN AND IS FORECAST TO
REMAIN WELL-ESTABLISHED FOR THE NEXT FEW DAYS. NUMERICAL TRACK
FORECAST MODELS HAVE COME INTO BETTER AGREEMENT THAT THE STORM WILL
MAINTAIN THE SAME GENERAL MOTION FOR THE NEXT COUPLE OF DAYS.
BEYOND THREE DAYS...THE FATE OF THE STORM WILL BE PARTIALLY
CONTROLLED BY A MIDDLE-LEVEL TROUGH CURRENTLY OVER THE BAHAMAS.
THIS TROUGH IS FORECAST TO CUT OFF INTO A LOW AND HEAD WESTWARD
UNDER A BUILDING SOUTHEAST UNITED STATES HIGH. MOST OF THE GUIDANCE
SHOWS THE LOW REMAINING FARTHER AWAY FROM DEAN WITH STRONGER
RIDGING CONTINUING ACROSS THE SOUTHWESTERN ATLANTIC OCEAN THAN IN
PREVIOUS MODEL RUNS. THIS SOLUTION WOULD FAVOR A MORE WESTWARD
TRACK IN THE LONG-RANGE..AND THE OFFICIAL FORECAST IS SHIFTED IN
THAT DIRECTION NEAR THE END OF THE FORECAST.

STEADY INTENSIFICATION OF THIS SYSTEM SEEMS TO BE THE BEST BET AS
VERTICAL WIND SHEAR IS FORECAST TO BE LIGHT BY ALL MODELS AND SEA
SURFACE TEMPERATURES UNDER THE STORM START TO RISE.  THE ONLY
NEGATING FACTOR TO INTENSIFICATION MIGHT BE THE ATMOSPHERIC
STABILITY AS SUGGESTED BY THE SHIPS MODEL.  HOWEVER...INTENSITY
GUIDANCE INDICATES THAT DEAN WILL BE A HURRICANE BEFORE IT
ENTERS THE EASTERN CARIBBEAN. THE GFDL/HWRF/SHIPS MODELS ALL
FORECAST DEAN TO BE A MAJOR HURRICANE BY DAY 5...AND SO DOES THE
OFFICIAL FORECAST.  

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/1500Z 12.4N  46.0W    50 KT
 12HR VT     16/0000Z 12.7N  48.6W    55 KT
 24HR VT     16/1200Z 13.1N  52.2W    60 KT
 36HR VT     17/0000Z 13.7N  55.8W    65 KT
 48HR VT     17/1200Z 14.2N  59.2W    75 KT
 72HR VT     18/1200Z 15.5N  66.0W    85 KT
 96HR VT     19/1200Z 16.5N  72.0W    95 KT
120HR VT     20/1200Z 18.0N  78.0W   105 KT
 
$$
FORECASTER BLAKE
 

WTNT44 KNHC 152036
TCDAT4
TROPICAL STORM DEAN DISCUSSION NUMBER  10
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT WED AUG 15 2007
 
DEAN CONTINUES TO ORGANIZE THIS AFTERNOON. ALTHOUGH THE CLOUD TOPS
HAVE WARMED RECENTLY...THE LAST FEW VISIBLE SATELLITE PICTURES
INDICATE A TIGHTLY CURVED BAND WRAPPING AROUND THE CENTER. AMSU AND
TRMM MICROWAVE IMAGES HAVE ALSO SUGGESTED THE FORMATION OF A
PARTIAL EYEWALL. MOST OBJECTIVE AND SUBJECTIVE DVORAK INTENSITY
ESTIMATES ARE INCREASING...AND THE CURRENT INTENSITY IS RAISED TO
55 KT.
 
THE INITIAL MOTION HAS SHIFTED MORE TO THE WEST-NORTHWEST IN THE
PAST SIX HOURS...AROUND 285/19. THIS MOVEMENT TOWARD THE
WEST-NORTHWEST IS EXPECTED TO BE BRIEF AS DEEP-LAYERED RIDGING TO
THE NORTH OF DEAN STRENGTHENS OVERNIGHT...FORCING THE STORM ON MORE
OF A WESTWARD COURSE TOMORROW. THE GLOBAL MODELS NOW SUGGEST THAT
ANY INTERACTION WITH A MIDDLE-LEVEL TROUGH CURRENTLY OVER THE
BAHAMAS WILL BE LIMITED AS THAT FEATURE IS FORECAST TO ADVANCE
WESTWARD AS AN INVERTED TROUGH WELL AHEAD OF DEAN. NUMERICAL TRACK
GUIDANCE IS IN VERY GOOD AGREEMENT WITH THIS SCENARIO...SHOWING THE
STORM IN THE VICINITY OF THE NORTHWESTERN CARIBBEAN SEA IN ABOUT 5
DAYS. THE OFFICIAL FORECAST IS SHIFTED A LITTLE TO THE NORTH DURING
THE FIRST 36 HOURS...BUT IS MUCH FASTER AND TO THE WEST OF THE
PREVIOUS TRACK NEAR THE END OF THE PERIOD. IT IS WORTH NOTING THAT
THE OFFICIAL FORECAST IS STILL SLOWER THAN THE NUMERICAL MODEL
CONSENSUS.

BASED ON WHAT WE THINK WE KNOW ABOUT INTENSITY CHANGE...THERE DO NOT
SEEM TO BE TOO MANY INHIBITING FACTORS TO A FUTURE INTENSIFICATION
OF DEAN.  GLOBAL MODELS UNANIMOUSLY DEVELOP A LARGE UPPER-LEVEL
ANTICYCLONE NEAR THE CENTER OF THE HURRICANE AS THE SYSTEM TRAVELS
INTO THE CARIBBEAN SEA.  IN COMBINATION WITH VERY DEEP WARM
WATERS...THIS PATTERN WOULD FAVOR THE DEVELOPMENT OF A POWERFUL
HURRICANE.  THE OFFICIAL INTENSITY FORECAST IS HIGHER THAN THE
PREVIOUS NHC FORECAST AND IS IN GOOD AGREEMENT WITH A CONSENSUS OF
THE SHIPS...GFDL...HWRF...AND LGEM MODELS.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      15/2100Z 13.1N  47.9W    55 KT
 12HR VT     16/0600Z 13.5N  50.8W    65 KT
 24HR VT     16/1800Z 14.1N  54.7W    70 KT
 36HR VT     17/0600Z 14.6N  58.6W    75 KT
 48HR VT     17/1800Z 15.1N  62.3W    85 KT
 72HR VT     18/1800Z 16.0N  69.5W    95 KT
 96HR VT     19/1800Z 17.0N  76.0W   105 KT
120HR VT     20/1800Z 18.5N  83.0W   115 KT
 
$$
FORECASTER BLAKE
 

WTNT44 KNHC 160252
TCDAT4
TROPICAL STORM DEAN DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT WED AUG 15 2007
 
DEAN HAS CONTINUED TO GRADUALLY BECOME BETTER ORGANIZED THIS
EVENING...WITH A 2311 UTC TRMM PASS SUGGESTING THAT A SMALL BANDING
EYE FEATURE MAY BE FORMING. THE 00Z DVORAK SATELLITE INTENSITY
ESTIMATES WERE 55 KT...HOWEVER...THE SATELLITE APPEARANCE HAS
IMPROVED SINCE THEN AND THE ADVISORY INTENSITY HAS BEEN INCREASED
TO 60 KT. 

THE INITIAL MOTION ESTIMATE IS 280/20. DEAN IS FORECAST TO CONTINUE
MOVING WEST TO WEST-NORTHWESTWARD SOUTH OF A DEEP-LAYER RIDGE
LOCATED OVER THE CENTRAL ATLANTIC. THE TRACK GUIDANCE IS TIGHTLY
CLUSTERED ON THIS MOTION DURING THE NEXT 72 HOURS. AT DAYS 4 AND
5...THE TRACK GUIDANCE HAS A BIT MORE SPREAD...BUT STILL IS IN GOOD
AGREEMENT ON A CONTINUED WEST-NORTHWEST MOTION INTO THE
NORTHWESTERN CARIBBEAN SEA. THE GLOBAL MODELS SHOW VERY LITTLE
INTERACTION BETWEEN DEAN AND A MIDDLE-LEVEL TROUGH CURRENTLY OVER
THE BAHAMAS...AS THEY CONTINUE TO MOVE THE TROUGH WESTWARD AHEAD OF
DEAN. THE NOGAPS IS A LITTLE SLOWER TO MOVE THE TROUGH WEST AND ITS
TRACK IS THEREFORE A LITTLE FARTHER NORTH THAN THE REST OF THE
GUIDANCE. THE NEW OFFICIAL TRACK FORECAST IS NEAR THE MIDDLE OF THE
GUIDANCE ENVELOPE AND CLOSE TO THE GUNA MODEL CONSENSUS.
 
THERE ARE SEEMINGLY FEW FACTORS THAT WOULD INHIBIT STRENGTHENING
DURING THE FORECAST PERIOD.  AS MENTIONED IN THE PREVIOUS
DISCUSSION...THE MODELS UNANIMOUSLY DEVELOP A LARGE UPPER-LEVEL
ANTICYCLONE OVER DEAN AS IT MOVES INTO THE CARIBBEAN SEA.
MYSTERIOUSLY...THE GFDL AND HWRF MODELS HAVE BACKED OFF ON THEIR
RESPECTIVE INTENSITY FORECASTS.  HOWEVER...THE SHIPS AND LGEM
MODELS CONTINUE TO INDICATE STEADY STRENGTHENING AND THE OFFICIAL
INTENSITY FORECAST IS UNCHANGED FROM THE PREVIOUS ADVISORY.

AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT WILL BE 
INVESTIGATING DEAN TOMORROW AFTERNOON...AND THE NOAA GULFSTREAM-IV
WILL CONDUCT A SYNOPTIC SURVEILLANCE MISSION FOR THE 17/00Z
ANALYSIS CYCLE.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0300Z 13.1N  50.2W    60 KT
 12HR VT     16/1200Z 13.6N  53.2W    65 KT
 24HR VT     17/0000Z 14.2N  57.2W    70 KT
 36HR VT     17/1200Z 14.8N  61.1W    75 KT
 48HR VT     18/0000Z 15.3N  64.7W    85 KT
 72HR VT     19/0000Z 16.3N  71.5W    95 KT
 96HR VT     20/0000Z 17.8N  78.5W   105 KT
120HR VT     21/0000Z 19.5N  85.5W   115 KT
 
$$
FORECASTER BROWN
 

WTNT44 KNHC 160908
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  12
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 AM EDT THU AUG 16 2007
 
DEAN HAS CONTINUED TO STRENGTHEN THIS MORNING...WITH OCCASIONAL
GLIMPSES OF AN EYE IN INFRARED SATELLITE IMAGERY AND CLOUD TOPS
COLDER THAN -70C NEAR THE CENTER.  SATELLITE INTENSITY ESTIMATES
ARE 65 KT FROM TAFB AND SAB...SO DEAN IS UPGRADED TO THE FIRST
HURRICANE OF THE 2007 HURRICANE SEASON.

THE INITIAL MOTION IS 280/21.  DEAN IS ON THE SOUTH SIDE OF A
DEEP-LAYER RIDGE...WHICH LARGE-SCALE MODELS FORECAST TO BUILD
WESTWARD DURING THE FORECAST PERIOD.  THIS BUILDING RIDGE IS
FORECAST TO PUSH ASIDE A MID/UPPER-LEVEL LOW CURRENTLY EAST OF
FLORIDA...AND SHOULD THIS HAPPEN THAT SYSTEM WOULD HAVE LITTLE
INTERACTION WITH DEAN.   THE PATTERN EVOLUTION SHOULD KEEP DEAN
MOVING QUICKLY WESTWARD TO WEST-NORTHWESTWARD THROUGH THE FORECAST
PERIOD.  THE TRACK GUIDANCE IS IN GOOD AGREEMENT WITH THIS
SCENARIO...AND THE MODELS ARE VERY TIGHTLY CLUSTERED AROUND A TRACK
THROUGH THE CARIBBEAN SEA TO NEAR THE YUCATAN PENINSULA IN FIVE
DAYS.  THE NEW FORECAST TRACK IS BASICALLY AN UPDATE OF THE
PREVIOUS PACKAGE....AND IS IN BEST AGREEMENT WITH THE VARIOUS
CONSENSUS MODELS.

THERE APPEARS TO BE LITTLE TO KEEP DEAN FROM STRENGTHENING THROUGH
THE FORECAST PERIOD.  THE SHIPS MODEL CALLS FOR THE SYSTEM TO REACH
115 KT BY THE END OF THE PERIOD...WHILE THE EXPERIMENTAL LGE MODEL
IS CALLING FOR 127 KT.  THE GFDL CALLS FOR DEAN TO BECOME A MAJOR
HURRICANE OVER THE WESTERN CARIBBEAN...ALTHOUGH ODDLY ENOUGH IT
CALLS FOR LITTLE CHANGE IN STRENGTH DURING THE FIRST 60 HR OF THE
FORECAST.  THE INTENSITY FORECAST HAS BEEN NUDGED UPWARD FOR THE
FIRST 96 HR IN GOOD AGREEMENT WITH THE SHIPS MODEL.
 
AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT WILL BE
INVESTIGATING DEAN THIS AFTERNOON..AND THE NOAA GULFSTREAM-IV
WILL CONDUCT A SYNOPTIC SURVEILLANCE MISSION FOR THE 17/00Z
ANALYSIS CYCLE.
 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0900Z 13.4N  52.3W    65 KT
 12HR VT     16/1800Z 13.9N  55.4W    70 KT
 24HR VT     17/0600Z 14.4N  59.4W    80 KT
 36HR VT     17/1800Z 14.9N  63.0W    90 KT
 48HR VT     18/0600Z 15.4N  66.5W   100 KT
 72HR VT     19/0600Z 16.5N  73.5W   105 KT
 96HR VT     20/0600Z 18.0N  80.5W   110 KT
120HR VT     21/0600Z 20.0N  87.5W   115 KT
 
$$
FORECASTER BEVEN
 

WTNT44 KNHC 161450
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  13
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 AM EDT THU AUG 16 2007
 
DEAN IS CONTINUING TO INTENSIFY. THE HURRICANE HAS DEVELOPED A SMALL
CLOUD-FILLED EYE THIS MORNING ON VISIBLE SATELLITE IMAGES AND THE
CIRRUS OUTFLOW IS EXPANDING IN ALL QUADRANTS. SUBJECTIVE DVORAK
ESTIMATES FROM TAFB/SAB ARE 77 KT...WHILE OBJECTIVE ESTIMATES ARE
HIGHER. THE INITIAL INTENSITY IS RAISED TO 80 KT. AN AIR FORCE
RESERVE HURRICANE HUNTER WILL BE IN THE EYE OF DEAN LATER TODAY TO
OBTAIN A BETTER ESTIMATE OF THE INTENSITY. WIND AND MAXIMUM SEAS
DATA FROM NOAA BUOY 41010 WERE CRITICAL FOR THIS ADVISORY.
 
THE INITIAL MOTION IS 280/21.  THERE IS LITTLE CHANGE TO THE
PREVIOUS FORECAST REASONING. A STRONG DEEP-LAYERED RIDGE SHOULD
CONTROL DEAN'S MOVEMENT DURING THE NEXT FEW DAYS.  THIS RIDGE SHOULD
FORCE THE HURRICANE ON A SPEEDY WESTWARD TRACK THROUGH THE CENTRAL
CARIBBEAN SEA.  MODEL GUIDANCE IS IN CLOSE AGREEMENT ON THE TRACK
THROUGH ABOUT 3 DAYS.  THEREAFTER...AS THE HURRICANE APPROACHES THE
NORTHWESTERN CARIBBEAN SEA...MOST OF THE GUIDANCE SUGGESTS THAT
DEAN WILL REACH THE WESTERN PERIPHERY OF THE SUBTROPICAL RIDGE AND
ATTEMPT TO MOVE MORE TO THE WEST-NORTHWEST.  GUIDANCE IS IN GOOD
AGREEMENT ON THIS SCENARIO AS WELL...EXCEPT FOR THE GFDL.  IT IS
STALLING A MIDDLE-LEVEL LOW...CURRENTLY OVER THE BAHAMAS...IN THE
EASTERN GULF OF MEXICO.  THIS SOLUTION ALLOWS THE HURRICANE TO MOVE
MORE TO THE NORTHWEST INTO THE CENTRAL GULF OF MEXICO.  THIS
SOLUTION IS CONSIDERED AN OUTLIER AT THIS TIME.  HOWEVER...THE
OFFICIAL FORECAST IS NUDGED A LITTLE TO THE NORTH AT 120 HR IN
DEFERENCE TO THE GFDL FORECAST.
 
ALL GLOBAL MODELS ARE DEVELOPING A LARGE 200 MB ANTICYCLONE AROUND
DEAN DURING THE NEXT FEW DAYS.  IN COMBINATION WITH THE DEEP WARM
WATER OF THE CARIBBEAN SEA...DEAN IS LIKELY TO BECOME A MAJOR
HURRICANE IN THE EASTERN CARIBBEAN SEA.  THE OFFICIAL FORECAST USES
A BLEND OF THE SHIPS...LGEM...AND GFDL MODELS...WHICH DEVELOP THIS
SYSTEM INTO AN EXTREMELY DANGEROUS CATEGORY 4 HURRICANE BY THE TIME
IT REACHES THE NORTHWESTERN CARIBBEAN SEA.
 
THE NOAA GULFSTREAM-IV WILL CONDUCT A SYNOPTIC SURVEILLANCE MISSION
FOR THE 17/00Z NUMERICAL GUIDANCE.  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/1500Z 13.7N  54.3W    80 KT
 12HR VT     17/0000Z 14.1N  57.4W    90 KT
 24HR VT     17/1200Z 14.6N  61.4W    95 KT
 36HR VT     18/0000Z 15.1N  64.9W   100 KT
 48HR VT     18/1200Z 15.6N  68.4W   105 KT
 72HR VT     19/1200Z 17.0N  75.5W   110 KT
 96HR VT     20/1200Z 18.5N  82.5W   120 KT
120HR VT     21/1200Z 21.0N  89.0W    80 KT...INLAND
 
$$
FORECASTER BLAKE
 

WTNT44 KNHC 162031
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  14
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT THU AUG 16 2007
 
AN AIR FORCE HURRICANE HUNTER AIRCRAFT HAS BEEN IN THE EYE OF DEAN
AND THE DATA SO FAR INDICATE THAT THE MINIMUM PRESSURE HAS BEEN
FLUCTUATION BETWEEN 974 AND 979 MB. MAXIMUM WINDS ARE ESTIMATED AT
85 KNOTS. THE CURRENT CONVECTIVE BANDING STRUCTURE AND THE
EXPANSION OF THE UPPER-LEVEL OUTFLOW OBSERVED ON SATELLITE IMAGES
SUGGEST THAT DEAN IS STRENGTHENING AT THIS TIME. DEAN IS EXPECTED
TO CARRY AN UPPER-LEVEL ANTICYCLONE WITH IT...ON ITS WESTWARD TRACK
ACROSS THE CARIBBEAN. THIS PATTERN IS CONDUCIVE TO STRENGTHENING.
ONCE DEAN REACHES THE WESTERN CARIBBEAN AND MOVES OVER AN AREA OF
VERY HIGH OCEAN HEAT...IT COULD BECOME A CATEGORY FOUR HURRICANE.
THIS IS CONSISTENT WITH THE SHIPS MODEL AND WITH DYNAMICAL
GUIDANCE...MAINLY THE GFDL AND THE HWRF WHICH MAKE DEAN A VERY
INTENSE HURRICANE.
 
DEAN IS MOVING TOWARD THE WEST OR 280 DEGREES AT 20 KNOTS. A STRONG
AND DEEP ANTICYCLONE IS FORECAST TO REMAIN ANCHORED NORTH OF DEAN.
THIS PATTERN WOULD PROVIDE A CONTINUED WESTWARD STEERING DURING THE
NEXT 3 TO 4 DAYS WITH SOME WEST-NORTHWESTWARD COMPONENT AS THE
HURRICANE REACHES THE EDGE OF THE HIGH BY DAY FIVE.  TRACK MODELS
ARE IN OUTSTANDING AGREEMENT BRINGING THE HURRICANE ACROSS THE
CARIBBEAN SEA. THIS ADDS CONFIDENCE TO THE TRACK FORECAST.
 
THE FRENCH BUOY...41001...RECENTLY REPORTED SUSTAINED WINDS OF 50
KNOTS. THIS INFORMATION HELPED WITH ESTIMATES OF THE WIND RADII.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/2100Z 14.0N  56.5W    85 KT
 12HR VT     17/0600Z 14.4N  59.7W    90 KT
 24HR VT     17/1800Z 15.0N  63.5W    95 KT
 36HR VT     18/0600Z 15.5N  67.0W   100 KT
 48HR VT     18/1800Z 16.0N  70.5W   110 KT
 72HR VT     19/1800Z 17.5N  78.0W   115 KT
 96HR VT     20/1800Z 19.5N  84.5W   120 KT
120HR VT     21/1800Z 22.0N  90.5W    90 KT
 
$$
FORECASTER AVILA/BLAKE
 

WTNT44 KNHC 170250
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  15
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT THU AUG 16 2007
 
THE SATELLITE PRESENTATION OF DEAN HAS DETERIORATED A BIT OVER THE
LAST 12 HOURS...WITH NO EVIDENCE OF AN EYE IN CONVENTIONAL OR
MICROWAVE IMAGERY. THE SFMR INSTRUMENT ON THE EARLIER AIR FORCE
FLIGHT RECORDED A PEAK SURFACE WIND OF 88 KT AROUND 19Z IN THE
SOUTHEAST PORTION OF THE EYEWALL...ALONG WITH VERY LITTLE WIND IN
THE SOUTHWEST QUADRANT OF THE CIRCULATION. BASED ON THE EARLIER
AIRCRAFT DATA AND RECENT STRUCTURAL TRENDS...THE INITIAL INTENSITY
IS HELD AT 85 KT.  COMMUNICATIONS DIFFICULTIES DURING THE
RECONNAISSANCE MISSION PREVENTED MUCH OF THE DATA FROM GETTING TO
US...BUT DROPSONDE DATA CALLED IN AFTERWARD BY THE CREW INDICATE
THE CENTRAL PRESSURE IS A LITTLE LOWER THAN PREVIOUSLY ESTIMATED...
ABOUT 976 MB.

THE INITIAL MOTION IS 275/22. DEAN IS SOUTH OF A MID-LEVEL RIDGE
THAT HAS BEEN MOVING WESTWARD IN TANDEM WITH THE CYCLONE. GLOBAL
MODEL GUIDANCE IS IN EXCELLENT AGREEMENT THAT IT WILL CONTINUE TO
DO SO FOR MOST OF THE FORECAST PERIOD...AND THE GUIDANCE IS VERY
TIGHTLY CLUSTERED ON A WEST TO WEST-NORTHWEST TRACK FOR AT LEAST
THE NEXT 72 HOURS. AFTER THAT...THE TRACK OF DEAN WILL DEPEND ON
HOW MUCH INTERACTION THERE IS BETWEEN THE HURRICANE AND A MID- TO
UPPER-LEVEL LOW CURRENTLY NORTHEAST OF THE BAHAMAS. ALL THE
AVAILABLE GUIDANCE CURRENTLY MOVES THIS LOW WESTWARD OUT OF THE WAY
AND SHOWS VERY LITTLE INTERACTION BETWEEN THE TWO...AND HENCE ONLY
A MODEST RIGHTWARD BEND IN THE TRACK ON DAYS 4 AND 5.   THE
OFFICIAL FORECAST IS BASICALLY AN UPDATE OF THE PREVIOUS ADVISORY
TRACK.  GIVEN THE UNCERTAINTY IN GLOBAL MODEL FORECASTS AT LONG
RANGES HOWEVER...A DIFFERENT EVOLUTION WITH THE UPPER LOW IS NOT
OUT OF THE QUESTION.

DEAN CONTINUES TO EXHIBIT A STRONG OUTFLOW PATTERN...AND THIS
FAVORABLE UPPER FLOW IS EXPECTED TO PERSIST FOR THE NEXT TWO TO
THREE DAYS.  DATA FROM THE NOAA G-IV MISSION THIS EVENING SHOW NO
EVIDENCE OF UNFAVORABLE THERMODYNAMICS IN THE NEAR ENVIRONMENT...
AND THE AVAILABLE OBJECTIVE GUIDANCE INDICATES CONTINUED
STRENGTHENING IN THE CARIBBEAN.  THE UPPER FLOW COULD BE A LITTLE
LESS FAVORABLE IN THE WESTERN CARIBBEAN...PARTICULARLY IF THE UPPER
LOW LAGS A BIT.  THE OFFICIAL FORECAST CALLS FOR SLIGHTLY FASTER
DEVELOPMENT THAN THE PREVIOUS ADVISORY BUT ENDS UP IN THE SAME
PLACE...AND IS IN GOOD AGREEMENT WITH THE AVAILABLE OBJECTIVE
GUIDANCE.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0300Z 14.1N  58.7W    85 KT
 12HR VT     17/1200Z 14.5N  61.9W    90 KT
 24HR VT     18/0000Z 15.1N  65.8W    95 KT
 36HR VT     18/1200Z 15.7N  69.2W   105 KT
 48HR VT     19/0000Z 16.4N  72.6W   115 KT
 72HR VT     20/0000Z 18.0N  80.0W   120 KT
 96HR VT     21/0000Z 19.5N  86.0W   120 KT
120HR VT     22/0000Z 22.0N  92.0W    90 KT
 
$$
FORECASTER FRANKLIN
 

WTNT44 KNHC 170853
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 AM EDT FRI AUG 17 2007
 
THE CONVECTIVE ORGANIZATION OF DEAN IS NOT VERY IMPRESSIVE IN EITHER
SATELLITE IMAGERY OR IMAGERY FROM THE FRENCH RADAR ON MARTINIQUE. 
THERE ARE ONLY OCCASIONAL GLIMPSES OF A RAGGED EYE ON RADAR...AND
THE EYEWALL HAS BEEN AT BEST ABOUT 50 PERCENT COVERAGE.  SATELLITE
INTENSITY ESTIMATES ARE 77 KT FROM BOTH TAFB AND SAB...WHICH ARE
UNCHANGED FROM EARLIER.  THE INITIAL INTENSITY WILL REMAIN 85 KT
FOR THIS ADVISORY...BUT IT IS POSSIBLE THIS IS A LITTLE GENEROUS.

THE INITIAL MOTION IS 275/21.  DEAN IS ON THE SOUTH SIDE OF A
DEEP-LAYER RIDGE...AND THIS SHOULD CONTINUE FOR THE NEXT 72 HR WITH
DEAN REMAINING ON A GENERAL WESTWARD TO WEST-NORTHWESTWARD TRACK. 
THE LARGE-SCALE MODELS HAVE SEEMINGLY RESPONDED TO THE G-IV JET
MISSION BY SHOWING A SLIGHTLY WEAKER RIDGE NORTH OF DEAN...WITH A
MOTION THAT IS SLOWER AND A LITTLE TO THE RIGHT OF PREVIOUS
FORECASTS.  GIVEN THE INITIAL MOTION...THE FIRST 12 HR OF THE
FORECAST TRACK WILL BE ESSENTIALLY UNCHANGED FROM THE PREVIOUS
PACKAGE...WITH A SLIGHT NUDGE TO THE RIGHT FROM 12-72 HR.  AFTER 72
HR...THE FORECAST IS BECOMING MORE PROBLEMATIC DUE TO UNCERTAINTIES
IN THE EVENTUAL INTERACTION OF DEAN AND THE UPPER-LEVEL LOW
FORECAST TO BE OVER THE GULF OF MEXICO.  THE GFDL AND UKMET MODELS
NOW CALL FOR DEAN TO TURN NORTHWESTWARD INTO THE CENTRAL
GULF...WHILE THE CANADIAN...NOGAPS...AND EUROPEAN MODELS CONTINUE
TO FORECAST A WESTWARD MOTION ACROSS THE YUCATAN PENINSULA INTO THE
BAY OF CAMPECHE.  THE GFS AND THE VARIOUS CONSENSUS MODELS ARE
BETWEEN THESE TWO EXTREMES.  THE FORECAST TRACK AFTER 72 HR IS ALSO
NUDGED A LITTLE TO THE RIGHT IN AGREEMENT WITH THE CONSENSUS
GUIDANCE.
 
THE DEVELOPMENT OF DEAN HAS APPARENTLY BEEN SLOWED BY A COMBINATION
OF DRY AIR INTRUSION IN THE WESTERN SEMICIRCLE AND LIGHT WESTERLY
SHEAR.  THESE CONDITIONS MAY PERSIST FOR ANOTHER 12-24 HR...SO THE
INTENSITY FORECAST CALLS FOR SLOW STRENGTHENING DURING THIS TIME. 
AFTER 24 HR...CONDITIONS SHOULD BE FAVORABLE FOR SIGNIFICANT
STRENGTHENING...WITH MOST OF THE INTENSITY GUIDANCE CALLING FOR
DEAN TO REACH AT LEAST CATEGORY 4 STRENGTH.  THE INTENSITY FORECAST
IS THE SAME AS IN THE EARLIER ADVISORY THROUGH 72 HR...THEN
SLIGHTLY STRONGER THEREAFTER.  IT SHOULD BE NOTED THAT THE
WEAKENING FROM 96 TO 120 HR IS BASED ON DEAN CROSSING THE YUCATAN
PENINSULA...AND IF IT INSTEAD MOVES THROUGH THE YUCATAN CHANNEL IT
COULD REMAIN STRONGER.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0900Z 14.3N  60.9W    85 KT
 12HR VT     17/1800Z 14.7N  63.6W    90 KT
 24HR VT     18/0600Z 15.3N  67.0W    95 KT
 36HR VT     18/1800Z 16.1N  70.5W   105 KT
 48HR VT     19/0600Z 16.9N  74.0W   115 KT
 72HR VT     20/0600Z 18.5N  81.0W   120 KT
 96HR VT     21/0600Z 20.5N  87.0W   125 KT
120HR VT     22/0600Z 23.0N  92.0W    95 KT
 
$$
FORECASTER BEVEN
 

WTNT44 KNHC 170853
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 AM EDT FRI AUG 17 2007
 
THE CONVECTIVE ORGANIZATION OF DEAN IS NOT VERY IMPRESSIVE IN EITHER
SATELLITE IMAGERY OR IMAGERY FROM THE FRENCH RADAR ON MARTINIQUE. 
THERE ARE ONLY OCCASIONAL GLIMPSES OF A RAGGED EYE ON RADAR...AND
THE EYEWALL HAS BEEN AT BEST ABOUT 50 PERCENT COVERAGE.  SATELLITE
INTENSITY ESTIMATES ARE 77 KT FROM BOTH TAFB AND SAB...WHICH ARE
UNCHANGED FROM EARLIER.  THE INITIAL INTENSITY WILL REMAIN 85 KT
FOR THIS ADVISORY...BUT IT IS POSSIBLE THIS IS A LITTLE GENEROUS.

THE INITIAL MOTION IS 275/21.  DEAN IS ON THE SOUTH SIDE OF A
DEEP-LAYER RIDGE...AND THIS SHOULD CONTINUE FOR THE NEXT 72 HR WITH
DEAN REMAINING ON A GENERAL WESTWARD TO WEST-NORTHWESTWARD TRACK. 
THE LARGE-SCALE MODELS HAVE SEEMINGLY RESPONDED TO THE G-IV JET
MISSION BY SHOWING A SLIGHTLY WEAKER RIDGE NORTH OF DEAN...WITH A
MOTION THAT IS SLOWER AND A LITTLE TO THE RIGHT OF PREVIOUS
FORECASTS.  GIVEN THE INITIAL MOTION...THE FIRST 12 HR OF THE
FORECAST TRACK WILL BE ESSENTIALLY UNCHANGED FROM THE PREVIOUS
PACKAGE...WITH A SLIGHT NUDGE TO THE RIGHT FROM 12-72 HR.  AFTER 72
HR...THE FORECAST IS BECOMING MORE PROBLEMATIC DUE TO UNCERTAINTIES
IN THE EVENTUAL INTERACTION OF DEAN AND THE UPPER-LEVEL LOW
FORECAST TO BE OVER THE GULF OF MEXICO.  THE GFDL AND UKMET MODELS
NOW CALL FOR DEAN TO TURN NORTHWESTWARD INTO THE CENTRAL
GULF...WHILE THE CANADIAN...NOGAPS...AND EUROPEAN MODELS CONTINUE
TO FORECAST A WESTWARD MOTION ACROSS THE YUCATAN PENINSULA INTO THE
BAY OF CAMPECHE.  THE GFS AND THE VARIOUS CONSENSUS MODELS ARE
BETWEEN THESE TWO EXTREMES.  THE FORECAST TRACK AFTER 72 HR IS ALSO
NUDGED A LITTLE TO THE RIGHT IN AGREEMENT WITH THE CONSENSUS
GUIDANCE.
 
THE DEVELOPMENT OF DEAN HAS APPARENTLY BEEN SLOWED BY A COMBINATION
OF DRY AIR INTRUSION IN THE WESTERN SEMICIRCLE AND LIGHT WESTERLY
SHEAR.  THESE CONDITIONS MAY PERSIST FOR ANOTHER 12-24 HR...SO THE
INTENSITY FORECAST CALLS FOR SLOW STRENGTHENING DURING THIS TIME. 
AFTER 24 HR...CONDITIONS SHOULD BE FAVORABLE FOR SIGNIFICANT
STRENGTHENING...WITH MOST OF THE INTENSITY GUIDANCE CALLING FOR
DEAN TO REACH AT LEAST CATEGORY 4 STRENGTH.  THE INTENSITY FORECAST
IS THE SAME AS IN THE EARLIER ADVISORY THROUGH 72 HR...THEN
SLIGHTLY STRONGER THEREAFTER.  IT SHOULD BE NOTED THAT THE
WEAKENING FROM 96 TO 120 HR IS BASED ON DEAN CROSSING THE YUCATAN
PENINSULA...AND IF IT INSTEAD MOVES THROUGH THE YUCATAN CHANNEL IT
COULD REMAIN STRONGER.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/0900Z 14.3N  60.9W    85 KT
 12HR VT     17/1800Z 14.7N  63.6W    90 KT
 24HR VT     18/0600Z 15.3N  67.0W    95 KT
 36HR VT     18/1800Z 16.1N  70.5W   105 KT
 48HR VT     19/0600Z 16.9N  74.0W   115 KT
 72HR VT     20/0600Z 18.5N  81.0W   120 KT
 96HR VT     21/0600Z 20.5N  87.0W   125 KT
120HR VT     22/0600Z 23.0N  92.0W    95 KT
 
$$
FORECASTER BEVEN
 

WTNT44 KNHC 171457
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  17
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 AM EDT FRI AUG 17 2007
 
THE CENTER OF DEAN CROSSED THE LESSER ANTILLES THIS MORNING BETWEEN
ST. LUCIA AND MARTINIQUE AS INDICATED BY THE MARTINIQUE RADAR.  AT
0842 UTC...THE METEOROLOGICAL SERVICE OF MARTINIQUE REPORTED
SUSTAINED WINDS OF 66 KNOTS WITH GUSTS TO 90 KNOTS. AN AIR FORCE
PLANE REACHED THE HURRICANE AND MEASURED A MINIMUM PRESSURE OF 964
MB...FLIGHT LEVEL WINDS OF 100 KNOTS AND A CLOSED EYEWALL.  THE
CLOUD PATTERN HAS BECOME BETTER ORGANIZED SINCE YESTERDAY WITH
PLENTY OF BANDING FEATURES AND OUTFLOW IN ALL QUADRANTS. LATEST
VISIBLE IMAGE SHOWS AN EYE FEATURE.  BOTH SATELLITE PRESENTATION
AND DATA FROM THE SFMR ON THE PLANE SUPPORT AN INITIAL INTENSITY OF
90 KNOTS. THE OFFICIAL INTENSITY FORECAST CALLS FOR STRENGTHENING
SINCE GUIDANCE SUGGESTS THAT THE SHEAR WILL BE LOW ACROSS THE
CARIBBEAN. DEAN COULD BECOME A VERY DANGEROUS HURRICANE WHEN IT
REACHES THE WESTERN CARIBBEAN WHERE THE OCEAN HEAT CONTENT IS THE
HIGHEST. IN FACT THE OFFICIAL FORECAST IS A CONSENSUS OF
SHIPS...GFDL AND HWRF MODELS.
 
THE MOTION OF DEAN...280/18...CONTINUES TO BE CONTROLLED BY A STRONG
RIDGE TO THE NORTH. A MID- TO UPPER-LEVEL LOW OVER THE WESTERN
BAHAMAS IS EXPECTED TO RUN WESTWARD AHEAD OF THE HURRICANE AND THE
ONLY POSSIBLE INFLUENCE ON THE TRACK OF THE HURRICANE IS TO ADD A
SMALL WEST-NORTHWESTWARD COMPONENT IN THE LATER PERIODS.  THE
OFFICIAL FORECAST FOLLOWS THE MIDDLE OF THE GUIDANCE ENVELOPE WITH A
SLIGHT ADJUSTMENT TO THE NORTH DUE TO THE GFDL AND UKMET MODELS.
THE GFDL SOLUTION INSISTS ON A MORE WEST-NORTHWEST TRACK THROUGH THE
YUCATAN CHANNEL...BRINGING DEAN INTO THE NORTHWEST GULF OF MEXICO
AS A STRONGER HURRICANE THAN INDICATED IN THE OFFICIAL FORECAST. IT
SHOULD BE NOTED THAT GUIDANCE FOR DAY 4 AND 5 IS MORE UNCERTAIN
TODAY THAN YESTERDAY.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/1500Z 14.6N  62.6W    90 KT
 12HR VT     18/0000Z 15.0N  65.5W   100 KT
 24HR VT     18/1200Z 15.8N  69.0W   105 KT
 36HR VT     19/0000Z 16.7N  72.3W   110 KT
 48HR VT     19/1200Z 17.5N  75.5W   120 KT
 72HR VT     20/1200Z 19.5N  82.0W   130 KT
 96HR VT     21/1200Z 21.5N  88.0W   100 KT...INLAND
120HR VT     22/1200Z 24.0N  94.0W   105 KT
 
$$
FORECASTER AVILA
 

WTNT44 KNHC 171754
TCDAT4
HURRICANE DEAN SPECIAL DISCUSSION NUMBER  18
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
145 PM EDT FRI AUG 17 2007
 
THIS SPECIAL ADVISORY IS BEING ISSUED TO UPDATE THE INITIAL
INTENSITY OF HURRICANE DEAN TO 110 KNOTS BASED ON FLIGHT LEVEL WIND
DATA OF 124 KNOTS JUST MEASURED BY AN AIR FORCE RECONNAISSANCE
AIRCRAFT. THE FORECAST INTENSITY HAS BEEN ADJUSTED UPWARD
ACCORDINGLY.  THIS ADVISORY SUPERSEDES THE INTERMEDIATE 2 PM AST
PUBLIC ADVISORY.
   
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/1745Z 14.8N  63.6W   110 KT
 12HR VT     18/0000Z 15.0N  65.5W   115 KT
 24HR VT     18/1200Z 15.8N  69.0W   120 KT
 36HR VT     19/0000Z 16.7N  72.3W   125 KT
 48HR VT     19/1200Z 17.5N  75.5W   130 KT
 72HR VT     20/1200Z 19.5N  82.0W   130 KT
 96HR VT     21/1200Z 21.5N  88.0W   100 KT...INLAND
120HR VT     22/1200Z 24.0N  94.0W   105 KT
 
$$
FORECASTER AVILA/MAINELLI
 

WTNT44 KNHC 172043
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT FRI AUG 17 2007
 
DATA FROM THE AIR FORCE HURRICANE HUNTER PLANE EARLIER TODAY
INDICATED THAT DEAN REACHED 110 KNOTS.  NEXT PLANE IS EXPECTED TO
REACH DEAN AROUND 00 UTC TONIGHT. SATELLITE IMAGES CONTINUE TO SHOW
AN EYE FEATURE...NUMEROUS CYCLONICALLY CURVED CONVECTIVE BANDS
WHICH ARE STILL AFFECTING A LARGE PORTION OF THE LESSER ANTILLES.
THE  OUTFLOW IS WELL ESTABLISHED IN ALL QUADRANTS. ALTHOUGH THE
POSSIBILITY OF SOME FLUCTUATIONS IN INTENSITY DUE TO EYEWALL
REPLACEMENT CYCLES COULD OCCUR AT ANY TIME...THE SHEAR IS FORECAST
TO REMAIN LOW AND THE OCEAN TEMPERATURE INCREASES WESTWARD. THIS
WOULD CALL FOR AN OVERALL UPWARD INTENSITY TREND. THIS IS
SUPPORTED BY THE SHIPS....GFDL AND HWRF INTENSITY GUIDANCE.
 
DEAN IS MOVING TOWARD THE WEST OR 280 DEGREES AT 18 KNOTS. THE
STEERING PATTERN CONTINUES TO BE CONTROLLED BY THE HIGH PRESSURE
SYSTEM TO THE NORTH OF THE HURRICANE AND THE MID TO UPPER-LEVEL LOW
OVER THE SOUTHWESTERN ATLANTIC AND FLORIDA. THIS LOW IS FORECAST
TO WEAKEN AND MOVE WESTWARD AND BE REPLACED BY A RIDGE. THIS
PATTERN WOULD MAINTAIN DEAN OVER THE CARIBBEAN ON A GENERAL
WESTWARD TRACK ACROSS NORTHERN YUCATAN AND THE WESTERN GULF OF
MEXICO. THE GFDL SHOWS A MORE NORTHWESTERLY TRACK ACROSS EXTREME
WESTERN CUBA AND THE CENTRAL GULF OF MEXICO. WHILE THIS SOLUTION IS
OUTSIDE THE OVERALL MODEL GUIDANCE ENVELOPE...IT CAN NOT BE RULE
OUT COMPLETELY SINCE THIS MODEL HAS AN EXCELLENT FORECAST TRACK
HISTORY.   THE OFFICIAL TRACK FORECAST IS AN UPDATE OF THE PREVIOUS
ONE AND FOLLOWS THE MODEL CONSENSUS.
 
THE BOTTOM LINE IS THAT DEAN IS EXPECTED TO BE A DANGEROUS HURRICANE
THROUGH THE NEXT SEVERAL DAYS...AND ALL INTERESTS IN THE CARIBBEAN
SEA AND THE GULF OF MEXICO SHOULD CLOSELY MONITOR THE PROGRESS OF
DEAN.
 
  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      17/2100Z 15.0N  64.5W   110 KT
 12HR VT     18/0600Z 15.5N  67.4W   115 KT
 24HR VT     18/1800Z 16.4N  70.8W   120 KT
 36HR VT     19/0600Z 17.3N  74.0W   125 KT
 48HR VT     19/1800Z 18.0N  77.0W   130 KT
 72HR VT     20/1800Z 20.0N  84.0W   130 KT
 96HR VT     21/1800Z 22.0N  90.0W   100 KT...INLAND
120HR VT     22/1800Z 24.5N  96.0W   105 KT
 
$$
FORECASTER AVILA
 

WTNT44 KNHC 180301
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  20
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT FRI AUG 17 2007
 
DEAN HAS BEEN STEADILY INTENSIFYING TONIGHT.  THE U.S. AIR FORCE
RECONNAISSANCE AIRCRAFT RECENTLY MEASURED MAXIMUM FLIGHT-LEVEL
WINDS OF 138 KT...CORRESPONDING TO ABOUT 124 KT AT THE SURFACE.  IN
ADDITION...THE AIRCRAFT IS EQUIPPED WITH THE STEPPED-FREQUENCY
MICROWAVE RADIOMETER WHICH MEASURED WINDS AS STRONG AS 123 KT THIS
EVENING.  NOT SURPRISINGLY...THE CENTRAL PRESSURE HAS BEEN
DROPPING...WITH THE LATEST AIRCRAFT MEASUREMENT BEING 937 MB.  THE
ADVISORY INTENSITY IS SET TO 125 KT...WHICH IS ALSO CONSISTENT WITH
DVORAK INTENSITY ESTIMATES.  THE AIRCRAFT DATA ALSO INDICATE THE
STORM HAS BECOME A GOOD BIT LARGER...AND WIND RADII HAVE BEEN
EXPANDED IN ALL QUADRANTS.  DEAN MIGHT ALSO HAVE A CLOSE ENCOUNTER
WITH NOAA BUOY 42059...LESS THAN 100 N MI DIRECTLY AHEAD OF THE
CENTER OF THE HURRICANE...IN A FEW HOURS.

THE INITIAL MOTION ESTIMATE IS 275/16...JUST A LITTLE SLOWER THAN
BEFORE.  THE OVERALL TRACK FORECAST REASONING HAS NOT CHANGED...AND
THE MODELS ARE IN GOOD AGREEMENT THROUGH 72 HOURS ON A TRACK TOWARD
THE NORTHWESTERN CARIBBEAN.  THEREAFTER...THE MODELS NOTABLY
DISAGREE AND HAVE GENERALLY SHIFTED A BIT TO THE SOUTH...INCLUDING
THE NORTHERN OUTLYING GFDL.  THE OFFICIAL FORECAST...HOWEVER...HAS
NOT CHANGED NOTICEABLY...SINCE THE MODELS MIGHT SHIFT BACK THE
OTHER WAY.  THE SIGNIFICANT SPREAD IN THE MODELS AT DAYS FOUR AND
FIVE IS INDICATIVE OF THE LARGE UNCERTAINTIES TYPICAL OF THOSE
LONGER FORECAST RANGES.  THE NHC WIND SPEED PROBABILITY TEXT AND
GRAPHICAL PRODUCTS INCLUDED IN THIS ADVISORY PACKAGE ALSO REFECT
THESE UNCERTAINTIES.  THE CHANCES OF TROPICAL STORM FORCE WINDS ARE
SIMILAR AT EACH LOCATION ALONG THE ENTIRE WESTERN AND NORTHERN
COASTS OF THE GULF OF MEXICO...AND IT IS TOO EARLY TO DIFFERENTIATE
THE RISK OF HURRICANE FORCE WINDS BETWEEN ANY OF THESE LOCATIONS.

THE FUTURE INTENSITY OF DEAN...GIVEN THE WEAK SHEAR AND WARM WATERS
AHEAD...WILL LIKELY BE CONTROLLED BY INTERNAL STRUCTURAL CHANGES
AND/OR BRIEF INTERACTIONS WITH LAND.  THE OFFICIAL FORECAST KEEPS
THE CURRENT INTENSITY THROUGH 72 HOURS...AND IS ONLY LOWERED ON
DAYS 4 AND 5 DUE TO POTENTIAL PASSAGE OVER YUCATAN.
 
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/0300Z 14.9N  65.9W   125 KT
 12HR VT     18/1200Z 15.5N  68.4W   130 KT
 24HR VT     19/0000Z 16.4N  71.7W   135 KT
 36HR VT     19/1200Z 17.3N  75.0W   135 KT
 48HR VT     20/0000Z 18.2N  78.4W   135 KT
 72HR VT     21/0000Z 20.0N  85.5W   140 KT
 96HR VT     22/0000Z 22.5N  91.5W   110 KT...INLAND
120HR VT     23/0000Z 25.0N  97.5W   110 KT
 
$$
FORECASTER KNABB
 

WTNT44 KNHC 180305
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  20...CORRECTED
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT FRI AUG 17 2007

..CORRECTED ERRONEOUS INDICATOR OF INLAND AT 96 HOURS IN TABLE...
 
DEAN HAS BEEN STEADILY INTENSIFYING TONIGHT.  THE U.S. AIR FORCE
RECONNAISSANCE AIRCRAFT RECENTLY MEASURED MAXIMUM FLIGHT-LEVEL
WINDS OF 138 KT...CORRESPONDING TO ABOUT 124 KT AT THE SURFACE.  IN
ADDITION...THE AIRCRAFT IS EQUIPPED WITH THE STEPPED-FREQUENCY
MICROWAVE RADIOMETER WHICH MEASURED WINDS AS STRONG AS 123 KT THIS
EVENING.  NOT SURPRISINGLY...THE CENTRAL PRESSURE HAS BEEN
DROPPING...WITH THE LATEST AIRCRAFT MEASUREMENT BEING 937 MB.  THE
ADVISORY INTENSITY IS SET TO 125 KT...WHICH IS ALSO CONSISTENT WITH
DVORAK INTENSITY ESTIMATES.  THE AIRCRAFT DATA ALSO INDICATE THE
STORM HAS BECOME A GOOD BIT LARGER...AND WIND RADII HAVE BEEN
EXPANDED IN ALL QUADRANTS.  DEAN MIGHT ALSO HAVE A CLOSE ENCOUNTER
WITH NOAA BUOY 42059...LESS THAN 100 N MI DIRECTLY AHEAD OF THE
CENTER OF THE HURRICANE...IN A FEW HOURS.

THE INITIAL MOTION ESTIMATE IS 275/16...JUST A LITTLE SLOWER THAN
BEFORE.  THE OVERALL TRACK FORECAST REASONING HAS NOT CHANGED...AND
THE MODELS ARE IN GOOD AGREEMENT THROUGH 72 HOURS ON A TRACK TOWARD
THE NORTHWESTERN CARIBBEAN.  THEREAFTER...THE MODELS NOTABLY
DISAGREE AND HAVE GENERALLY SHIFTED A BIT TO THE SOUTH...INCLUDING
THE NORTHERN OUTLYING GFDL.  THE OFFICIAL FORECAST...HOWEVER...HAS
NOT CHANGED NOTICEABLY...SINCE THE MODELS MIGHT SHIFT BACK THE
OTHER WAY.  THE SIGNIFICANT SPREAD IN THE MODELS AT DAYS FOUR AND
FIVE IS INDICATIVE OF THE LARGE UNCERTAINTIES TYPICAL OF THOSE
LONGER FORECAST RANGES.  THE NHC WIND SPEED PROBABILITY TEXT AND
GRAPHICAL PRODUCTS INCLUDED IN THIS ADVISORY PACKAGE ALSO REFLECT
THESE UNCERTAINTIES.  THE CHANCES OF TROPICAL STORM FORCE WINDS ARE
SIMILAR AT EACH LOCATION ALONG THE ENTIRE WESTERN AND NORTHERN
COASTS OF THE GULF OF MEXICO...AND IT IS TOO EARLY TO DIFFERENTIATE
THE RISK OF HURRICANE FORCE WINDS BETWEEN ANY OF THESE LOCATIONS.

THE FUTURE INTENSITY OF DEAN...GIVEN THE WEAK SHEAR AND WARM WATERS
AHEAD...WILL LIKELY BE CONTROLLED BY INTERNAL STRUCTURAL CHANGES
AND/OR BRIEF INTERACTIONS WITH LAND.  THE OFFICIAL FORECAST CALLS
FOR AN INTENSITY NEAR THE CATEGORY 4/5 THRESHOLD THROUGH 72
HOURS...AND IS ONLY LOWERED ON DAYS 4 AND 5 DUE TO POTENTIAL
PASSAGE OVER YUCATAN.

 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/0300Z 14.9N  65.9W   125 KT
 12HR VT     18/1200Z 15.5N  68.4W   130 KT
 24HR VT     19/0000Z 16.4N  71.7W   135 KT
 36HR VT     19/1200Z 17.3N  75.0W   135 KT
 48HR VT     20/0000Z 18.2N  78.4W   135 KT
 72HR VT     21/0000Z 20.0N  85.5W   140 KT
 96HR VT     22/0000Z 22.5N  91.5W   110 KT
120HR VT     23/0000Z 25.0N  97.5W   110 KT...NEAR COAST OF MEXICO
 
$$
FORECASTER KNABB
 

WTNT44 KNHC 180833
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  21
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 AM EDT SAT AUG 18 2007
 
NEAR 0500 UTC...AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT
REPORTED 154 KT FLIGHT-LEVEL WINDS IN THE NORTHERN EYEWALL OF
DEAN...AND ALSO REPORTED THAT THE CENTRAL PRESSURE FELL TO 930 MB. 
THE FLIGHT-LEVEL WINDS COULD HAVE JUSTIFIED CALLING DEAN A CATEGORY
FIVE HURRICANE.  HOWEVER...DATA FROM DROPSONDES...THE STEPPED-
FREQUENCY MICROWAVE RADIOMETER...AND SATELLITE INTENSITY ESTIMATES
DID NOT SUPPORT THAT STATUS.  THE INTENSITY WAS THUS SET TO A
SLIGHTLY MORE CONSERVATIVE 130 KT.  THERE HAS BEEN LITTLE CHANGE IN
THE SATELLITE APPEARANCE OF DEAN SINCE THE AIRCRAFT LEFT...SO 130
KT IS THE INITIAL INTENSITY FOR THIS ADVISORY.

THE INITIAL MOTION IS 275/15...AGAIN SLIGHTLY SLOWER THAN BEFORE. 
DEAN CONTINUES TO BE STEERED BY A RIDGE OVER THE WESTERN ATLANTIC
WHICH SHOULD BUILD WESTWARD DURING THE NEXT 72-96 HR AS AN
UPPER-LEVEL LOW OVER SOUTH FLORIDA MOVES WESTWARD.  IN THE SHORT
TERM...THE GUIDANCE IS IN GOOD AGREEMENT ON A WEST-NORTHWESTWARD
TRACK TOWARD JAMAICA.  THE OFFICIAL FORECAST WILL FOLLOW
THIS...WITH THE TRACK DOWN THE LEFT SIDE OF THE GUIDANCE ENVELOPE
DUE TO THE INITIAL MOTION.   AFTER THAT...UKMET...GFS...AND
CONSENSUS MODELS CALL FOR A MOTION TOWARD THE NORTHERN YUCATAN
PENINSULA AND NORTHEASTERN MEXICO.  THE GFDL CALLS FOR A MOTION
THROUGH THE YUCATAN CHANNEL TO THE TEXAS COAST...WHILE THE ECMWF
AND NOGAPS CALL FOR A MORE WESTERLY MOTION THROUGH THE CENTRAL
YUCATAN AND THE BAY OF CAMPECHE INTO MAINLAND MEXICO.  THE TRACK
FORECAST IS NUDGED A LITTLE SOUTH OF THE PREVIOUS FORECAST IN BEST
AGREEMENT WITH THE CONSENSUS MODELS.

SINCE UPPER-LEVEL WINDS ARE FORECAST TO REMAIN FAVORABLE...THE
INTENSITY FORECAST CALLS FOR A GRADUAL INCREASE IN STRENGTH THROUGH
72 HR DUE TO INCREASING SEA SURFACE TEMPERATURES AND MAXIMUM
POTENTIAL INTENSITY.  HOWEVER...THERE ARE LIKELY TO BE SIGNIFICANT
FLUCTUATIONS ON TOP OF THIS DUE TO DIFFICULT TO TIME EYEWALL
REPLACEMENT CYCLES.  PASSAGE OVER THE YUCATAN PENINSULA SHOULD
CAUSE SOME WEAKENING...FOLLOWED BY RE-INTENSIFICATION OVER THE GULF
OF MEXICO.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/0900Z 15.1N  67.3W   130 KT
 12HR VT     18/1800Z 15.6N  69.6W   130 KT
 24HR VT     19/0600Z 16.5N  72.8W   135 KT
 36HR VT     19/1800Z 17.6N  76.4W   135 KT
 48HR VT     20/0600Z 18.5N  80.0W   135 KT
 72HR VT     21/0600Z 20.5N  86.5W   140 KT
 96HR VT     22/0600Z 22.5N  92.5W   110 KT
120HR VT     23/0600Z 24.5N  98.0W   115 KT...INLAND
 
$$
FORECASTER BEVEN
 

WTNT44 KNHC 181448
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  22
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 AM EDT SAT AUG 18 2007
 
AN AIR FORCE PLANE ENTERED THE EYE OF DEAN THIS MORNING AND FOUND
THAT THE HURRICANE HAS NOT WEAKENED AND THE INITIAL INTENSITY
REMAINS AT 130 KNOTS. IN FACT...THE MINIMUM PRESSURE DROPPED TO 924
MB AT AROUND 1200 UTC AND THEN UP TO 929 MB JUST RECENTLY. DEAN
WILL LIKELY GO THROUGH EYEWALL CYCLES DURING THE NEXT FEW DAYS
RESULTING IN FLUCTUATIONS IN INTENSITY. HOWEVER...THE PEAK
INTENSITY IS EXPECTED TO OCCUR IN THE NORTHWESTERN CARIBBEAN
BETWEEN THE CAYMAN ISLANDS AND YUCATAN WHERE THE OCEAN HEAT CONTENT
IS VERY HIGH.  DEAN COULD BECOME A CATEGORY FIVE AT ANY TIME BEFORE
IT REACHES YUCATAN.
 
THE STEERING PATTERN HAS BEEN VERY STEADY. DEAN IS MOVING TOWARD THE
WEST OR 290 DEGREES AT 15 KNOTS STEERED BY A HIGH OVER THE WESTERN
ATLANTIC AND A LOW OVER FLORIDA.  THE LOW IS FORECAST TO MOVE
WESTWARD AND BE REPLACED BY A STRONG RIDGE BY ALL GLOBAL MODELS.
THIS PATTERN WILL KEEP DEAN ON A GENERAL WEST-NORTHWEST TO WEST
TRACK ACROSS THE CARIBBEAN SEA IN THE DIRECTION OF JAMAICA...THE
CAYMAN ISLANDS AND YUCATAN. THIS IS CONSISTENT WITH TRACK MODELS
WITH THE EXCEPTION OF THE GFDL WHICH INSISTS ON A TRACK FARTHER TO
THE NORTH AND JUST CLIPPING THE NORTHEASTERN YUCATAN PENINSULA.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/1500Z 15.7N  68.6W   130 KT
 12HR VT     19/0000Z 16.4N  71.0W   130 KT
 24HR VT     19/1200Z 17.3N  74.3W   135 KT
 36HR VT     20/0000Z 18.3N  77.8W   125 KT...NEAR OR OVER JAMAICA
 48HR VT     20/1200Z 19.5N  81.4W   140 KT
 72HR VT     21/1200Z 21.5N  88.5W   100 KT...INLAND
 96HR VT     22/1200Z 23.0N  94.0W   110 KT
120HR VT     23/1200Z 25.4N 100.0W    50 KT...INLAND
 
$$
FORECASTER AVILA
 

WTNT44 KNHC 182024
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  23
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT SAT AUG 18 2007
 
THERE HAVE BEEN NO SIGNIFICANT CHANGES IN THE STRUCTURE OF DEAN
DURING THE PAST SEVERAL HOURS. THE LAST RECONNAISSANCE AIRCRAFT
INTO THE EYE MEASURED 930 MB AND THE REPORTED WINDS SUPPORT AN
INITIAL INTENSITY OF 130 KNOTS. HOWEVER...THE CREW OBSERVED A
DOUBLE EYEWALL AND THE PRESENCE OF THIS FEATURE WILL PROBABLY
RESULT IN SHORT TERM FLUCTUATIONS IN INTENSITY. THE SATELLITE
PRESENTATION IS OUTSTANDING WITH A WELL DEFINED EYE...NUMEROUS
SPIRAL BANDS AND AN EXPANDING OUTFLOW. WITH AN ENVIRONMENT OF LOW
SHEAR AND VERY HIGH OCEANIC HEAT CONTENT BETWEEN THE CAYMAN ISLANDS
AND YUCATAN...SOME ADDITIONAL INTENSIFICATION IS POSSIBLE. IN
FACT...DEAN COULD BECOME A POTENTIALLY CATASTROPHIC CATEGORY FIVE
HURRICANE AT ANY TIME BEFORE IT REACHES YUCATAN.

THE HURRICANE IS HEADING ON A STEADY WEST-NORTHWESTWARD TRACK OR 285
DEGREES AT 16 KNOTS. THE STRONG HIGH TO THE NORTH OF THE HURRICANE
IS EXPECTED TO BUILD WESTWARD AS INDICATED BY THE LATEST GLOBAL
MODEL RUNS. THIS PATTERN CALLS FOR NO SIGNIFICANT CHANGE IN TRACK
OR SPEED THROUGH 5 DAYS...BUT PERHAPS WITH A SLIGHT TURN MORE TO THE
WEST IN A DAY OR SO. THE GFDL CONTINUES TO BE ON THE NORTHERN SIDE
OF THE GUIDANCE ENVELOPE AND IS THE ONLY MODEL THAT BRINGS THE
HURRICANE OVER THE SOUTHERN TEXAS COAST. THE OFFICIAL FORECAST GOES
ALONG WITH THE CONSENSUS OF THE DYNAMICAL MODELS AND KEEPS DEAN IN
THE BAY OF CAMPECHE OR SOUTHERN GULF OF MEXICO BY DAY FOUR. THERE
COULD BE VERY UNCERTAIN DAYS AHEAD SINCE THE GFDL HAS HAD A VERY
RELIABLE TRACK RECORD.

 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      18/2100Z 16.1N  70.2W   130 KT
 12HR VT     19/0600Z 16.8N  72.6W   135 KT
 24HR VT     19/1800Z 17.7N  76.0W   135 KT
 36HR VT     20/0600Z 18.5N  79.3W   125 KT
 48HR VT     20/1800Z 19.5N  83.0W   140 KT
 72HR VT     21/1800Z 21.5N  90.0W   100 KT
 96HR VT     22/1800Z 23.0N  96.0W   105 KT
120HR VT     23/1800Z 24.5N 101.5W    40 KT...INLAND
 
$$
FORECASTER AVILA
 

WTNT44 KNHC 190259
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  24
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT SAT AUG 18 2007
 
THE INNER CORE OF DEAN APPEARS TO BE UNDERGOING SOME CHANGES.  RADAR
IMAGERY ONBOARD THE AIR FORCE RECONNAISSANCE AIRCRAFT DEPICTS
CONCENTRIC EYEWALLS AT RADII OF ABOUT 10 AND 20 N MI...WITH THE
OUTER EYEWALL RECENTLY BECOMING A LITTLE BETTER DEFINED. 
FLIGHT-LEVEL WINDS HAVE ALSO REVEALED DOUBLE MAXIMA.  WIND DATA AT
FLIGHT LEVEL...FROM THE SFMR...AND FROM DROPSONDES DIRECTLY SUPPORT
AN INTENSITY OF NO MORE THAN ABOUT 115 KT.  THE CENTRAL
PRESSURE...HOWEVER...HAS BEEN GRADUALLY DROPPING AND WAS MOST
RECENTLY MEASURED AT 918 MB.  ASSUMING THAT THE MAXIMUM WIND HAS
NOT BEEN SAMPLED...THE ADVISORY INTENSITY IS SET TO 125 KT...BUT
THIS COULD BE A BIT ON THE HIGH SIDE.  THE AIRCRAFT WILL CONTINUE
TO INVESTIGATE DEAN FOR A FEW MORE HOURS TO SEE IF THE WINDS COME
BACK UP.

DEAN WOBBLED WESTWARD EARLIER THIS EVENING...BUT THE LONGER-TERM
MOTION TOWARD 280 DEGREES AT ABOUT 15 KT SEEMS TO HAVE RESUMED. AS
THE MODELS HAVE BEEN FORECASTING...THE MID- TO UPPER-LEVEL LOW THAT
WAS EAST OF FLORIDA A COUPLE OF DAYS AGO IS NOW OVER THE EASTERN
GULF OF MEXICO AND HEADED QUICKLY WESTWARD. THAT LOW IS FORECAST TO
BE REPLACED BY A LARGE AND STRONG RIDGE OVER THE SOUTHEASTERN
UNITED STATES DURING THE NEXT COUPLE OF DAYS...WHICH SHOULD
REINFORCE A GENERAL WEST-NORTHWESTWARD MOTION OF DEAN...THROUGH THE
NORTHWESTERN CARIBBEAN...OVER SOME PORTION OF THE YUCATAN
PENINSULA...AND INTO THE SOUTHERN GULF OF MEXICO. THE MODELS HAVE
IN GENERAL SHIFTED SLIGHTLY SOUTHWARD...INCLUDING THE GFDL WHICH IS
NO LONGER THE NORTHERN OUTLIER. THE GUIDANCE IS NOW IN VERY GOOD
AGREEMENT ON THE TRACK THROUGHOUT THE ENTIRE FIVE-DAY FORECAST
PERIOD...SO CONFIDENCE IN THE TRACK FORECAST IS INCREASING. THE
OFFICIAL TRACK FORECAST HAS BEEN ADJUSTED A TAD TO THE SOUTH AND IS
VERY NEAR THE DYNAMICAL MODEL CONSENSUS.

THE SHORT-TERM INTENSITY FORECAST IS A BIT UNCERTAIN GIVEN THE
DOUBLE EYEWALL STRUCTURE...BUT THE CENTRAL PRESSURE IS QUITE LOW AND
THE INNER CORE COULD QUICKLY REORGANIZE AT ANY TIME...SO ANY DIP IN
THE INTENSITY WILL PROBABLY BE SHORT-LIVED.  THROUGHOUT ITS STAY IN
THE CARIBBEAN SEA DURING THE NEXT 48 HOURS OR SO...ATMOSPHERIC AND
OCEANIC CONDITIONS REMAIN SUPPORTIVE OF A CATEGORY FOUR OR FIVE
INTENSITY AS SUGGESTED BY ALL OF THE OBJECTIVE GUIDANCE.  SINCE THE
NEW TRACK FORECAST RESULTS IN A LONGER STAY OVER THE YUCATAN
PENINSULA...THE OFFICIAL INTENSITY FORECAST HAS BEEN LOWERED
SLIGHTLY OVER THE SOUTHWESTERN GULF OF MEXICO...BUT STILL INDICATES
A MAJOR HURRICANE AT FINAL LANDFALL.
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/0300Z 16.2N  71.7W   125 KT
 12HR VT     19/1200Z 16.8N  74.3W   130 KT
 24HR VT     20/0000Z 17.6N  77.8W   130 KT
 36HR VT     20/1200Z 18.4N  81.4W   135 KT
 48HR VT     21/0000Z 19.3N  85.1W   140 KT
 72HR VT     22/0000Z 21.0N  92.0W    85 KT
 96HR VT     23/0000Z 23.0N  98.0W   100 KT...INLAND
120HR VT     24/0000Z 24.0N 101.0W    30 KT...INLAND
 
$$
FORECASTER KNABB
 

WTNT44 KNHC 190847
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  25
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 AM EDT SUN AUG 19 2007

THE LAST PENETRATION OF THE EYE OF THE HURRICANE BY THE AIR FORCE
HURRICANE HUNTERS WAS AT 0511 UTC.  THE AIRCRAFT REPORTED A MINIMUM
PRESSURE OF 921 MB BY DROPSONDE AND PEAK FLIGHT-LEVEL WINDS OF 130
KT OUTBOUND IN THE NORTHEAST QUADRANT.  SATELLITE IMAGERY SHOWS A
LESS DISTINCT EYE WITH SOME WARMING OF THE SURROUNDING CLOUD
TOPS...ALTHOUGH THE CLOUD PATTERN REMAINS VERY IMPRESSIVE WITH GOOD
SYMMETRY AND STRONG OUTFLOW OVER ALL QUADRANTS.  THE INITIAL
INTENSITY ESTIMATE IS KEPT AT 125 KT FOR THIS ADVISORY...WHICH MAY
BE A LITTLE ON THE HIGH SIDE.  IF INDEED DEAN HAS WEAKENED...THIS 
IS LIKELY THE RESULT OF INNER CORE PROCESSES...AND IS PROBABLY ONLY
A SHORT-TERM CHANGE.  THE LARGE-SCALE ATMOSPHERIC AND OCEANIC
ENVIRONMENT STILL APPEAR TO BE VERY FAVORABLE FOR STRENGTHENING...
SO....ASIDE FROM INNER-CORE-RELATED FLUCTUATIONS...DEAN HAS THE
POTENTIAL TO ATTAIN CATEGORY FIVE HURRICANE STATUS OVER THE
NORTHWESTERN CARIBBEAN SEA.  THIS IS SUPPORTED BY THE GFDL...
SHIPS...LGEM...AND FSSE GUIDANCE.  INTERACTION WITH THE YUCATAN
PENINSULA WILL CAUSE WEAKENING...AND THE AMOUNT OF RE-STRENGTHENING
OF DEAN OVER THE SOUTHWESTERN GULF OF MEXICO DEPENDS MAINLY ON HOW
LONG THE SYSTEM STAYS OVER WATER BEFORE MAKING ITS FINAL LANDFALL.

ASIDE FROM THE TROCHOIDAL WOBBLES THAT ARE COMMON WITH SUCH INTENSE
HURRICANES...THE MOTION HAS BEEN BETWEEN WEST AND WEST-NORTHWEST
OVER THE PAST 12-24 HOURS.  INITIAL MOTION ESTIMATE IS 285/16.  AS
THE MID- TO UPPER-LEVEL CYCLONE OVER THE EASTERN GULF OF MEXICO
CONTINUES TO SHIFT WESTWARD AHEAD OF DEAN...THE FUTURE TRACK OF THE
HURRICANE WILL BE CONTROLLED LARGELY BY A DEEP-LAYER HIGH PRESSURE
SYSTEM THAT IS FORECAST TO BUILD OVER THE SOUTHEASTERN UNITED
STATES.  THE TRACK GUIDANCE IS IN GOOD AGREEMENT ON A CONTINUED
WEST-NORTHWESTWARD MOTION THROUGHOUT THE FORECAST PERIOD.  ANY
CHANGES FROM THE PREVIOUS OFFICIAL TRACK FORECAST DURING THE FIRST
48 HOURS OR SO SHOULD BE CONSIDERED COSMETIC.  WE HAVE SHIFTED THE
OFFICIAL FORECAST TRACK SLIGHTLY SOUTHWARD IN THE LATTER PART OF
THE PERIOD...BUT NOT AS FAR SOUTH AS SHOWN BY THE GFS...U.K. MET.
AND ECMWF MODELS.  

IT IS IMPERATIVE NOT TO FOCUS ON THE EXACT FORECAST TRACK. 
CONSIDERING THE MARGIN OF ERROR OF NHC PREDICTIONS...THE CORE OF
THIS LARGE HURRICANE COULD EASILY BE 30-50 N MI ON EITHER SIDE OF
THE FORECAST TRACK DURING THE NEXT 12 HOURS OR SO.

ANOTHER AIR FORCE RECONNAISSANCE PLANE IS SCHEDULED TO MAKE A
POSITION AND INTENSITY FIX ON DEAN AROUND 1200 UTC.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/0900Z 16.6N  73.4W   125 KT
 12HR VT     19/1800Z 17.1N  76.0W   130 KT
 24HR VT     20/0600Z 17.9N  79.5W   130 KT
 36HR VT     20/1800Z 18.7N  83.0W   135 KT
 48HR VT     21/0600Z 19.5N  86.6W   140 KT
 72HR VT     22/0600Z 21.0N  93.5W    85 KT
 96HR VT     23/0600Z 22.5N  99.0W    50 KT...INLAND
120HR VT     24/0600Z 23.5N 103.0W    25 KT...INLAND
 
$$
FORECASTER PASCH/BROWN
 

WTNT44 KNHC 191459
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 AM EDT SUN AUG 19 2007
 
THE HURRICANE HUNTER AIRCRAFT REPORTED A PEAK FLIGHT-LEVEL WIND OF
142 KT IN THE NORTHWEST QUADRANT...WHICH WOULD SUPPORT THE CURRENT
ESTIMATED INTENSITY OF 125 KT.  CENTRAL PRESSURES HAVE BEEN SLOWLY
RISING...THE EYE DIAMETER HAS INCREASED OVER THE PAST 12
HOURS...AND THE RECONNAISSANCE DATA INDICATE A CONCENTRIC EYEWALL
STRUCTURE.  IN THE SHORT TERM...THERE COULD BE SOME BROADENING OF
THE WIND FIELD WITH FLUCTUATIONS IN STRENGTH AS THE CORE OF DEAN
APPROACHES JAMAICA...BUT FURTHER STRENGTHENING OVER THE DEEP WARM
WATERS OF THE NORTHWESTERN CARIBBEAN IS EXPECTED.

THERE HAS BEEN LITTLE CHANGE TO THE TRACK FORECAST PHILOSOPHY.  THE
INITIAL MOTION IS 280/16...WITH SOME EMBEDDED WOBBLES.  AS
THE MID- TO UPPER-LEVEL CYCLONE OVER THE EASTERN GULF OF MEXICO
CONTINUES TO SHIFT WESTWARD AHEAD OF DEAN...THE FUTURE TRACK OF THE
HURRICANE WILL BE CONTROLLED LARGELY BY A DEEP-LAYER HIGH PRESSURE
SYSTEM THAT IS FORECAST TO BUILD OVER THE SOUTHEASTERN UNITED
STATES.  THE TRACK GUIDANCE REMAINS IN GOOD AGREEMENT ON A CONTINUED
WEST-NORTHWESTWARD MOTION THROUGHOUT THE FORECAST PERIOD...AND THE
OFFICIAL FORECAST IS ESSENTIALLY AN UPDATE OF THE PREVIOUS
ADVISORY.


FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/1500Z 17.0N  75.1W   125 KT
 12HR VT     20/0000Z 17.5N  77.7W   125 KT
 24HR VT     20/1200Z 18.3N  81.2W   130 KT
 36HR VT     21/0000Z 19.0N  84.5W   140 KT
 48HR VT     21/1200Z 19.9N  88.2W   120 KT...INLAND
 72HR VT     22/1200Z 21.5N  95.0W   100 KT
 96HR VT     23/1200Z 23.0N 100.0W    40 KT...INLAND
120HR VT     24/1200Z...DISSIPATED
 
$$
FORECASTER FRANKLIN
 

WTNT44 KNHC 192047
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  27
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT SUN AUG 19 2007
 
THE RECONNAISSANCE AIRCRAFT COMPLETED ITS MISSION...FINDING PEAK
FLIGHT-LEVEL WINDS OF 144 KT...WITH PEAK SFMR WINDS OF 121 KT.  ONE
OF THE LAST EYEWALL DROPSONDES GAVE A SURFACE ESTIMATE OF 118 KT
DERIVED FROM THE LOWEST 150 METERS OF THE SOUNDING.  IN SPITE OF A
GRADUAL PRESSURE RISE...THESE DATA INDICATE THAT 125 KT IS STILL A
GOOD INTENSITY ESTIMATE.  CONCENTRIC EYEWALLS ARE APPARENT IN
MICROWAVE...CONVENTIONAL SATELLITE...AND AIRCRAFT DATA...WITH THE
STRONGEST WINDS NOW ASSOCIATED WITH THE OUTER EYEWALL.  SHORT-TERM
INTENSITY CHANGES WILL BE GOVERNED BY INNER-CORE PROCESSES THAT ARE
DIFFICULT TO TIME...BUT OVERALL CONDITIONS IN THE WESTERN CARIBBEAN
WOULD FAVOR FURTHER INTENSIFICATION...AND DEAN COULD VERY WELL
BECOME A CATEGORY FIVE HURRICANE DURING THE NEXT DAY OR TWO.
 
THE INITIAL MOTION IS 280/17. THERE IS NO MAJOR CHANGE TO THE
FORECAST THINKING...ALTHOUGH MODEL GUIDANCE HAS BEEN TRENDING
SOUTHWARD...WITH NEARLY ALL OF THE LARGE-SCALE MODELS BUILDING THE
SUBTROPICAL RIDGE WESTWARD IN TANDEM WITH DEAN. THE UPPER LOW IN
THE GULF OF MEXICO CONTINUES WESTWARD AND IS NOT EXPECTED TO BE A
MAJOR PLAYER IN THE FUTURE TRACK OF THE HURRICANE. THE OFFICIAL
FORECAST HAS BEEN SHIFTED A LITTLE TO THE SOUTH...BUT STILL LIES TO
THE NORTH OF ALL THE MAJOR MODELS EXCEPT FOR THE HWRF. ALTHOUGH I
CANNOT EXPLAIN WHY...THE DETERMINISTIC RUN OF THE GFS IS ALONG THE
SOUTHERN END OF THE GUIDANCE ENVELOPE...WHILE THE GFS ENSEMBLE
MEMBERS ARE ALMOST UNIFORMLY ALONG THE NORTHERN EDGE. BECAUSE MOST
OF THE GUIDANCE MODELS LIE TO THE SOUTH OF THE OFFICIAL FORECAST...
SOME ADDITIONAL SOUTHWARD ADJUSTMENTS TO THE TRACK ARE POSSIBLE.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      19/2100Z 17.3N  76.8W   125 KT
 12HR VT     20/0600Z 17.8N  79.4W   130 KT
 24HR VT     20/1800Z 18.4N  83.0W   135 KT
 36HR VT     21/0600Z 19.0N  86.5W   140 KT
 48HR VT     21/1800Z 19.9N  90.0W    80 KT...INLAND
 72HR VT     22/1800Z 21.5N  96.5W   100 KT
 96HR VT     23/1800Z 23.0N 101.0W    35 KT...INLAND
120HR VT     24/1800Z...DISSIPATED
 
$$
FORECASTER FRANKLIN/RHOME
 

WTNT44 KNHC 200300
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  28
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT SUN AUG 19 2007
 
THE EYE OF DEAN HAS BEEN PASSING JUST SOUTH OF JAMAICA SINCE ABOUT
1900 UTC AND HAS JUST CROSSED THE LONGITUDE OF NEGRIL ON THE
WESTERN END OF THE ISLAND.  THE CENTER CAME WITHIN ABOUT 20 N MI OF
PORTLAND POINT ON THE SOUTH-CENTRAL COAST...CLOSE ENOUGH TO BRING
HURRICANE-FORCE WINDS TO KINGSTON.  WHILE PASSING BY JAMAICA...
SATELLITE IMAGERY SUGGESTED THE EYE DIAMETER WAS GRADUALLY
SHRINKING.  AN AIR FORCE HURRICANE HUNTER AIRCRAFT ARRIVED IN THE
EYE OF DEAN AT 0130 UTC AND REVEALED THAT THE PRESSURE HAD FALLEN
TO NEAR 925 MB...AND THAT DEAN NOW HAS A SINGLE EYEWALL AT A
DIAMETER OF ABOUT 15 N MI.  MAXIMUM SURFACE WINDS FROM THE SFMR
HAVE BEEN 121 KT...AND FLIGHT-LEVEL WINDS HAVE BEEN AS HIGH AS 143
KT...BOTH OF WHICH SUPPORT MAINTAINING THE ADVISORY INTENSITY AT
125 KT.
 
DEAN IS HEADING TOWARD 280 DEGREES AT ABOUT 17 KT WITH STEERING
PROVIDED BY A STRENGTHENING MID-LEVEL RIDGE OVER THE SOUTHEASTERN
UNITED STATES.  THE MODELS ALL AGREE THAT THE RIDGE WILL GET EVEN
STRONGER AND MOVE A LITTLE WESTWARD WITH DEAN...MEANING THAT DEAN
WILL PROBABLY MOVE IN A RATHER STRAIGHT LINE UNTIL FINAL LANDFALL
IN MEXICO.  OVERALL THE MODELS HAVE AGAIN EDGED A LITTLE
SOUTHWARD...AND SO HAS THE OFFICIAL FORECAST.  THE NOAA
GULFSTREAM-IV JET CONDUCTED A SYNOPTIC SURVEILLANCE MISSION THIS
EVENING TO PROVIDE DATA FOR THE 0000 UTC MODEL CYCLE.  THE JET WILL
CONTINUE TO FLY MISSIONS EVERY 12 HOURS TO COLLECT DATA THROUGH THE
12Z MODEL CYCLE TUESDAY MORNING.
 
ALL OF THE OBJECTIVE GUIDANCE CALLS FOR STRENGTHENING IN THE
NORTHWESTERN CARIBBEAN WHERE THE SHEAR WILL REMAIN WEAK AND THE
OCEAN HEAT CONTENT VERY HIGH.  THE OFFICIAL FORECAST FOLLOWS SUIT
AND INDICATES THAT DEAN COULD REACH CATEGORY FIVE STATUS DURING THE
NEXT DAY OR SO.  THE HURRICANE WILL WEAKEN WHILE OVER YUCATAN IN
PROPORTION TO JUST HOW LONG IT SPENDS OVER LAND.  THE OPPORTUNITY
FOR RESTRENGTHENING OVER THE SOUTHWESTERN GULF LIKEWISE DEPENDS ON
THE EXACT TRACK...AND THAT WINDOW HAS BEEN SHORTENING WITH THE
SOUTHWARD SHIFTS IN TRACK.  ALTHOUGH NOT EXPLICITLY INDICATED IN
THE NEW OFFICIAL FORECAST...IT IS STILL POSSIBLE THAT DEAN COULD
RESTRENGTHEN AND AGAIN REACH MAJOR HURRICANE STATUS PRIOR TO FINAL
LANDFALL ALONG THE COAST OF MAINLAND MEXICO.

 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/0300Z 17.6N  78.8W   125 KT
 12HR VT     20/1200Z 18.0N  81.4W   130 KT
 24HR VT     21/0000Z 18.5N  84.9W   140 KT
 36HR VT     21/1200Z 19.2N  88.4W   105 KT...INLAND
 48HR VT     22/0000Z 19.8N  91.9W    80 KT
 72HR VT     23/0000Z 21.0N  99.0W    55 KT...INLAND
 96HR VT     24/0000Z...DISSIPATED
 
$$
FORECASTER KNABB
 

WTNT44 KNHC 200842
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  29
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 AM EDT MON AUG 20 2007
 
OBSERVATIONS FROM THE LAST AIR FORCE HURRICANE HUNTER MISSION AGAIN
INDICATED A CONCENTRIC EYEWALL STRUCTURE. THE PEAK FLIGHT-LEVEL
WIND SPEED WAS 145 KT WITH AN SFMR SURFACE WIND MEASUREMENT OF 125
KT IN THE NORTHEAST QUADRANT. A GPS DROPSONDE MEASURED A SURFACE
WIND SPEED OF 133 KT IN THE SAME QUADRANT...BUT BASED ON
LOWER-LAYER AVERAGES FROM THE SONDE...THIS PROBABLY DOES NOT QUITE
CORRESPOND TO A 1-MINUTE AVERAGE SURFACE WIND. BASED ON ALL OF
THESE DATA THE CURRENT INTENSITY IS SET AT 130 KT. DEAN IS MOVING
OVER WATERS OF EXTREMELY HIGH OCEANIC HEAT CONTENT WITH WEAK SHEAR
AND EXHIBITS A CLASSIC UPPER-TROPOSPHERIC OUTFLOW PATTERN. DEAN
CERTAINLY HAS THE POTENTIAL TO STRENGTHEN INTO A CATEGORY FIVE
HURRICANE WITHIN THE NEXT 24 HOURS AND THIS IS REFLECTED IN THE
OFFICIAL FORECAST. WEAKENING WILL OCCUR DUE TO THE TRANSIT OVER THE
YUCATAN PENINSULA AND THE OFFICIAL FORECAST ROUGHLY FOLLOWS THE
INLAND DECAY SHIPS MODEL. DEAN IS FORECAST TO RESTRENGTHEN OVER THE
BAY OF CAMPECHE...AND THE GFDL AND HWRF GUIDANCE SUGGEST THAT IT
COULD REGAIN MAJOR HURRICANE STATUS BEFORE MAKING ITS FINAL
LANDFALL. THIS IS NOT EXPLICITLY SHOWN IN THE OFFICIAL FORECAST BUT
ADDITIONAL STRENGTHENING WILL LIKELY OCCUR BETWEEN THE 48-HOUR
FORECAST AND LANDFALL.

AIRCRAFT AND SATELLITE FIXES OVER THE PAST SIX HOURS OR SO GIVE
ESSENTIALLY A DUE WESTWARD MOTION AT A SLIGHTLY FASTER FORWARD
SPEED...270/18.  AS A MID- TO UPPER-TROPOSPHERIC CYCLONE CONTINUES
MOVING WESTWARD OVER THE WESTERN GULF OF MEXICO...THE FLOW TO THE
SOUTH OF A STRENGTHENING DEEP-LAYER HIGH PRESSURE SYSTEM OVER THE
SOUTHEASTERN U.S. WILL BE THE DOMINANT STEERING MECHANISM FOR DEAN.
THEREFORE...A WESTWARD TO WEST-NORTHWESTWARD MOTION IS LIKELY FOR
THE NEXT COUPLE OF DAYS.  THE OFFICIAL FORECAST IS VERY SIMILAR TO
THE PREVIOUS ONE AND IS QUITE CLOSE TO THE GFDL...U.K.
MET...NOGAPS...AND GFS CONSENSUS AND FSU SUPERENSEMBLE TRACKS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/0900Z 17.7N  80.7W   130 KT
 12HR VT     20/1800Z 18.1N  83.5W   135 KT
 24HR VT     21/0600Z 18.8N  87.0W   140 KT
 36HR VT     21/1800Z 19.6N  90.5W    75 KT...INLAND
 48HR VT     22/0600Z 20.5N  94.0W    90 KT...BAY OF CAMPECHE
 72HR VT     23/0600Z 22.0N 100.5W    30 KT...INLAND
 96HR VT     24/0600Z...DISSIPATED
 
$$
FORECASTER PASCH/BROWN
 

WTNT44 KNHC 201447
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  30
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 AM EDT MON AUG 20 2007
 
THE NEXT RECONNAISSANCE FLIGHT WILL BE AT 18Z THIS AFTERNOON. IN THE
MEANTIME...RECENT MICROWAVE DATA SHOW A SINGLE EYEWALL THAT HAS
BECOME BETTER DEFINED WITH COLDER TOPS IN CONVENTIONAL SATELLITE
IMAGERY OVER THE PAST COUPLE OF HOURS. THE ADVISORY INTENSITY WILL
BE HELD AT 130 KT...BUT LATEST SATELLITE IMAGES INDICATE THAT DEAN
IS APPROACHING CATEGORY FIVE STATUS...AND IT IS EXPECTED REACH THAT
THRESHOLD LATER TODAY OVER THE DEEP WARM WATERS OF THE WESTERN
CARIBBEAN. ALTHOUGH SIGNIFICANT WEAKENING IS EXPECTED OVER THE
YUCATAN...DEAN SHOULD RETAIN HURRICANE STATUS DURING THE CROSSING
AND A HURRICANE WARNING IS THEREFORE REQUIRED FOR THE WESTERN COAST
OF THE YUCATAN AT THIS TIME. ALTHOUGH NOT EXPLICIT IN THE OFFICIAL
FORECAST BELOW...DEAN COULD REACH MAJOR HURRICANE AGAIN BEFORE ITS
FINAL LANDFALL.
 
THE INITIAL MOTION IS 285/18.  THERE HAS BEEN NO SIGNIFICANT CHANGE
TO THE TRACK FORECAST REASONING...MODEL GUIDANCE...OR OFFICIAL
FORECAST.  DEAN IS EXPECTED TO CONTINUE ON A TRACK BETWEEN WEST AND
WEST-NORTHWEST OVER THE NEXT TWO TO THREE DAYS TO THE SOUTH OF THE
WESTWARD-BUILDING SUBTROPICAL RIDGE.  THE OFFICIAL FORECAST IS VERY
CLOSE TO THE MODEL CONSENSUS WITHIN A VERY NARROW GUIDANCE
ENVELOPE.
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/1500Z 17.9N  82.4W   130 KT
 12HR VT     21/0000Z 18.2N  85.1W   140 KT
 24HR VT     21/1200Z 19.0N  88.6W   100 KT...INLAND
 36HR VT     22/0000Z 19.9N  92.2W    80 KT
 48HR VT     22/1200Z 21.0N  95.5W    95 KT
 72HR VT     23/1200Z 22.5N 102.0W    35 KT...INLAND
 96HR VT     24/1200Z...DISSIPATED
 
$$
FORECASTER FRANKLIN
 

WTNT44 KNHC 202033
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  31
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT MON AUG 20 2007
 
COMMUNICATIONS PROBLEMS ARE PREVENTING THE RECEIPT OF MOST DATA FROM
THE AIR FORCE RECONNAISSANCE AIRCRAFT THIS AFTERNOON...ALTHOUGH A
1930Z VORTEX FIX WAS RECEIVED. AT THAT TIME THE MINIMUM PRESSURE
WAS 918 MB...WITH MAXIMUM FLIGHT-LEVEL WINDS OF 151 KT. EARLIER IN
THE FLIGHT...A PEAK SFMR WIND OF 123 KT WAS OBSERVED.  DVORAK
CLASSIFICATIONS FROM TAFB AND SAB WERE 127 KT AT 18Z.  BASED ON
THESE DATA...THE INITIAL INTENSITY IS HELD AT 130 KT. ALL OBJECTIVE
GUIDANCE SHOWS ADDITIONAL INTENSIFICATION OVER THE DEEP WARM WATERS
OF THE WESTERN CARIBBEAN...AND DEAN COULD REACH CATEGORY FIVE
STATUS BEFORE MAKING LANDFALL. A 15Z MICROWAVE PASS SHOWS A PARTIAL
OUTER EYEWALL...BUT THIS WILL PROBABLY NOT HAVE ENOUGH TIME TO
INDUCE ANY WEAKENING BEFORE LANDFALL.  DEAN IS EXPECTED TO MAINTAIN
HURRICANE STRENGTH AS IT TRAVERSES THE YUCATAN PENINSULA...AND
APPROACH MAJOR HURRICANE STRENGTH AGAIN BEFORE ITS FINAL LANDFALL.
 
THE INITIAL MOTION IS 275/17.  DEAN IN EXPECTED TO MAINTAIN A TRACK
BETWEEN WEST AND WEST-NORTHWEST TO THE SOUTH OF THE WESTWARD-
BUILDING SUBTROPICAL RIDGE.  MOST OF THE DYNAMICAL MODEL GUIDANCE
HAS TRENDED SOUTH AND THE OFFICIAL FORECAST HAS BEEN NUDGED
SOUTHWARD.  ALL THE LARGE-SCALE MODELS TAKE THE MID-LEVEL VORTICITY
OF DEAN WEST-SOUTHWESTWARD ACROSS THE MOUNTAINS OF CENTRAL
MEXICO...AND THE OFFICIAL FORECAST NOW SHOWS A LEFTWARD BEND OF THE
TRACK AFTER FINAL LANDFALL.  I DO NOT ACTUALLY EXPECT A WELL-
DEFINED SURFACE CIRCULATION TO EXIST AT 72 HOURS...BUT A POINT IS
PROVIDED SO THAT IT DOESN'T APPEAR THAT THE TRACK ENDS IN THE GULF
OF MEXICO.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      20/2100Z 18.2N  84.2W   130 KT
 12HR VT     21/0600Z 18.5N  86.7W   140 KT
 24HR VT     21/1800Z 19.3N  90.2W    75 KT...INLAND
 36HR VT     22/0600Z 20.2N  93.6W    85 KT
 48HR VT     22/1800Z 21.0N  97.0W    95 KT
 72HR VT     23/1800Z 21.5N 103.0W    30 KT...INLAND
 96HR VT     24/1800Z...DISSIPATED
 
$$
FORECASTER FRANKLIN
 

WTNT44 KNHC 210258
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  32
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT MON AUG 20 2007
 
DEAN HAS TAPPED INTO ENERGY PROVIDED BY THE DEEP WARM WATERS OF THE
NORTHWESTERN CARIBBEAN SEA THIS EVENING...AND HAS REACHED CATEGORY
FIVE STATUS WITH AN INTENSITY OF 140 KT.  DURING THE LAST
PENETRATION BY THE AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT
AT 00Z...A CENTRAL PRESSURE OF 914 MB WAS MEASURED.  THE PEAK
FLIGHT-LEVEL WIND WAS 162 KT...WHICH CORRESPONDS TO ABOUT 145 KT AT
THE SURFACE.  DUE TO COMMUNICATIONS PROBLEMS...WE HAVE NOT RECEIVED
ALL OF THE DROPSONDE AND SFMR DATA IN REAL-TIME.  THE ADVISORY
INTENSITY IS SET TO A POSSIBLY CONSERVATIVE 140 KT...PENDING A MORE
THOROUGH EXAMINATION OF ALL OF THE AIRCRAFT DATA.  ANOTHER AIRCRAFT
WILL ARRIVE IN THE EYE OF DEAN IN A FEW HOURS...PRIOR TO LANDFALL
ALONG THE EAST COAST OF THE YUCATAN PENINSULA.  THE EVOLVING
SATELLITE PRESENTATION OF DEAN REVEALS AN INCREASINGLY SYMMETRIC
CONVECTIVE PATTERN...AND A VERY WELL-DEFINED AND GRADUALLY
CONTRACTING EYE WITH A DIAMETER OF ABOUT 20 N MI.  REPORTS FROM THE
AIRCRAFT...AND RECENT MICROWAVE SATELLITE IMAGERY...PROVIDE NO
INDICATIONS OF ANY INNER-CORE STRUCTURAL CHANGES THAT WOULD LEAD TO
WEAKENING PRIOR TO LANDFALL.  THE OFFICIAL INTENSITY FORECAST IS
ESSENTIALLY UNCHANGED.  DEAN IS EXPECTED TO MAINTAIN HURRICANE
STATUS DURING ITS ENTIRE STAY OVER YUCATAN...AND IT COULD STILL
REGAIN MAJOR HURRICANE STATUS OVER THE BAY OF CAMPECHE BEFORE FINAL
LANDFALL IN ABOUT 36 HOURS.

THE HURRICANE GENERALLY REMAINS ON TRACK WITH AN INITIAL MOTION OF
275/17.  A STRENGTHENING RIDGE OVER THE SOUTHEASTERN UNITED STATES
SHOULD CONTINUE TO PUSH DEAN ROUGHLY ALONG THIS SAME HEADING AND
SPEED FOR THE NEXT COUPLE OF DAYS UNTIL DISSIPATION OVER MAINLAND
MEXICO.  THE NEW OFFICIAL FORECAST IS AGAIN ADJUSTED TO THE SOUTH
IN ORDER TO MAINTAIN THE CURRENT WELL-ESTABLISHED HEADING...AND TO
BE IN BETTER AGREEMENT WITH A CONSENSUS OF THE GFDL...GFS...AND
NOGAPS MODELS.  ALONG THE NEW TRACK...DEAN WILL SPEND A LITTLE LESS
TIME OVER THE BAY OF CAMPECHE...AND WILL PASS A LITTLE CLOSER TO
THE NORTHERN COAST OF THE ISTHMUS OF TEHUANTEPEC DURING THE 24-36
HOUR PERIOD.  AS A RESULT...NEW WATCHES AND WARNINGS HAVE BEEN
ISSUED ALONG THE COAST OF MAINLAND MEXICO.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/0300Z 18.4N  86.0W   140 KT
 12HR VT     21/1200Z 18.7N  88.6W   140 KT...INLAND OVER YUCATAN
 24HR VT     22/0000Z 19.2N  92.1W    85 KT...BAY OF CAMPECHE
 36HR VT     22/1200Z 19.6N  95.6W    95 KT...BAY OF CAMPECHE
 48HR VT     23/0000Z 19.6N  99.1W    30 KT...INLAND OVER MEXICO
 72HR VT     24/0000Z...DISSIPATED
 
$$
FORECASTER KNABB/ROBERTS
 

WTNT44 KNHC 210900
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  33
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 AM EDT TUE AUG 21 2007
 
DEAN MADE LANDFALL ON THE EAST COAST OF THE YUCATAN PENINSULA NEAR
THE CRUISE SHIP PORT OF COSTA MAYA AROUND 0830 UTC...AND THE EYE IS
NOW JUST INLAND.  OBSERVATIONS FROM AN AIR FORCE HURRICANE HUNTER
PLANE INDICATE THAT THE HURRICANE WAS INTENSIFYING RIGHT UP TO
LANDFALL.  A PEAK FLIGHT-LEVEL WIND OF 165 KT WAS MEASURED JUST
NORTH OF THE EYE.  MAXIMUM SURFACE WINDS FROM THE SFMR WERE 124
KT...BUT IT IS HIGHLY LIKELY THAT THE MAXIMUM SURFACE WIND SPEED
WAS NOT REPORTED BY THE SFMR INSTRUMENT.  A GPS DROPSONDE IN THE
NORTHERN EYEWALL MEASURED A WIND SPEED OF 178 KT AVERAGED OVER THE
LOWEST 150 METERS OF THE SOUNDING.  BASED ON THE DROPSONDE AND THE
FLIGHT-LEVEL WINDS...THE INTENSITY IS SET AT 145 KT.  A DROPSONDE
IN THE EYE MEASURED A CENTRAL PRESSURE OF 906 MB JUST PRIOR TO
LANDFALL.  SOME HISTORIC NOTES ARE IN ORDER HERE.  THE 906 MB
CENTRAL PRESSURE IS THE NINTH LOWEST ON RECORD FOR AN ATLANTIC
BASIN HURRICANE...AND THE THIRD LOWEST AT LANDFALL BEHIND THE 1935
LABOR DAY HURRICANE IN THE FLORIDA KEYS AND HURRICANE GILBERT OF
1988 IN CANCUN MEXICO.  DEAN IS ALSO THE FIRST CATEGORY FIVE
HURRICANE TO MAKE LANDFALL IN THE ATLANTIC BASIN SINCE ANDREW OF
1992.
 
DEAN WILL WEAKEN AS IT TRAVERSES THE YUCATAN PENINSULA AND
THE AMOUNT OF WEAKENING WILL DEPEND ON HOW LONG THE CENTER REMAINS
OVER LAND.  OUR CURRENT THINKING IS THAT THE CYCLONE WILL STILL BE
A BORDERLINE CAT 1/2 HURRICANE WHEN IT EMERGES OVER THE BAY OF
CAMPECHE...BUT THERE IS CONSIDERABLE UNCERTAINTY IN THIS FORECAST.
ASSUMING THAT THE INNER CORE IS NOT TOO DISRUPTED BY ITS
INTERACTION WITH LAND...DEAN SHOULD REGAIN MAJOR HURRICANE STATUS
BEFORE ITS FINAL LANDFALL IN MAINLAND MEXICO.

INITIAL MOTION IS ESTIMATED TO BE 285/17.  DEEP LAYER HIGH PRESSURE
NEAR THE NORTHERN GULF COAST SHOULD STEER THE HURRICANE ON A
WEST-NORTHWESTWARD TO WESTWARD HEADING FOR THE NEXT COUPLE OF DAYS. 
THE OFFICIAL TRACK FORECAST IS SIMILAR TO THE PREVIOUS ONE.

THE HURRICANE WARNING IS EXTENDED WESTWARD ALONG THE BAY OF CAMPECHE
COASTLINE OF MEXICO.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/0900Z 18.7N  87.8W   145 KT
 12HR VT     21/1800Z 19.1N  90.4W    85 KT...INLAND
 24HR VT     22/0600Z 19.6N  93.9W    95 KT...OVER BAY OF CAMPECHE
 36HR VT     22/1800Z 20.1N  96.8W   105 KT...INLAND
 48HR VT     23/0600Z 20.5N 100.0W    25 KT...INLAND...DISSIPATING
 72HR VT     24/0600Z...DISSIPATED
 
$$
FORECASTER PASCH/BROWN
 

WTNT44 KNHC 211444
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  34
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 AM EDT TUE AUG 21 2007
 
AFTER MAKING LANDFALL IN A SPARSELY-POPULATED AREA...DEAN CONTINUES
TO TRAVERSE THE SPARSELY-POPULATED SOUTHERN PORTION OF THE YUCATAN
PENINSULA. THE EYE HAS FILLED AND CLOUD TOPS ARE WARMING. THE
INTENSITY IS ESTIMATED AT 90 KT BASED ON THE DECAY COMPONENT OF THE
SHIPS MODEL. DEAN IS EXPECTED TO EMERGE INTO THE BAY OF CAMPECHE IN
ANOTHER 3 TO 5 HOURS AS A HURRICANE...AND WILL HAVE ABOUT 18 HOURS
OVER WATER TO REGAIN STRENGTH. SHIPS AND GFDL GUIDANCE SUGGESTS
THAT DEAN COULD APPROACH MAJOR HURRICANE STATUS AGAIN...ALTHOUGH
THE AMOUNT OF RESTRENGTHENING WILL BE HARD TO GAUGE UNTIL WE SEE
HOW MUCH OF THE INNER CORE OF THE HURRICANE SURVIVES ITS PASSAGE
OVER LAND.
 
THE INITIAL MOTION IS 280/17. THERE IS NO SIGNIFICANT CHANGE TO THE
TRACK FORECASTING THINKING. DEEP LAYER HIGH PRESSURE NEAR THE
NORTHERN GULF COAST SHOULD STEER THE HURRICANE ON A WEST-
NORTHWESTWARD TO WESTWARD HEADING FOR THE NEXT COUPLE OF DAYS. THE
OFFICIAL TRACK FORECAST IS SIMILAR TO THE PREVIOUS ONE...AND IS IN
BEST AGREEMENT WITH THE GFS AND GFDL MODEL.
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/1500Z 19.0N  89.6W    90 KT
 12HR VT     22/0000Z 19.4N  92.2W    85 KT
 24HR VT     22/1200Z 20.0N  95.5W    95 KT
 36HR VT     23/0000Z 20.5N  98.7W    50 KT...INLAND
 48HR VT     23/1200Z 21.0N 101.5W    25 KT...INLAND
 72HR VT     24/1200Z...DISSIPATED
 
$$
FORECASTER FRANKLIN
 

WTNT44 KNHC 212031
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  35
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT TUE AUG 21 2007
 
DEAN HAS EMERGED INTO THE BAY OF CAMPECHE.  THE ADVISORY INTENSITY
OF 70 KT IS AGAIN BASED ON TYPICAL DECAY RATES...AND HIGHLY
UNCERTAIN.  AN AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT WILL
BE IN THE CYCLONE AROUND 00Z TO ASCERTAIN THE TRUE STRENGTH OF
DEAN.  BASED ON SATELLITE IMAGERY...THE INNER CORE OF DEAN APPEARS
TO BE LARGELY INTACT...WITH DEEP CONVECTION DIRECTLY OVER THE
CENTER.  THIS IS EXPECTED TO ALLOW RESTRENGTHENING TO BEGIN FAIRLY
QUICKLY...AND DEAN COULD BE VERY NEAR MAJOR HURRICANE STATUS BY THE
TIME OF ITS LANDFALL IN THE WESTERN GULF.  THE SHIPS MODEL FORECAST
APPEARS TO BE OVERLY INFLUENCED BY THE RECENT DECAY AND HAS BEEN
DISCOUNTED FOR THIS ADVISORY.  AFTER LANDFALL...THE SURFACE
CIRCULATION SHOULD RAPIDLY BECOME DISRUPTED OVER THE HIGH TERRAIN
OF CENTRAL MEXICO...ALTHOUGH MOISTURE FROM DEAN COULD END UP
WORKING ITS WAY INTO THE SOUTHWESTERN UNITED STATES OVER THE NEXT
SEVERAL DAYS.
 
THE INITIAL MOTION CONTINUES TO BE 280/17...AND THERE CONTINUES TO
BE NO SIGNIFICANT CHANGE TO THE TRACK FORECAST.  HIGH PRESSURE
NORTH OF THE GULF OF MEXICO WILL CONTINUE TO STEER DEAN ON A TRACK
JUST NORTH OF WEST.  MODEL GUIDANCE IS A LITTLE MORE DIVERGENT THIS
AFTERNOON...WITH THE UKMET SHOWING A BIT OF JOG TO THE RIGHT JUST
BEFORE LANDFALL.  HOWEVER...THE REST OF THE GUIDANCE IS LARGELY
UNCHANGED AND THE OFFICIAL FORECAST IS LARGELY AN UPDATE OF THE
PREVIOUS ADVISORY.
  
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      21/2100Z 19.4N  91.3W    70 KT
 12HR VT     22/0600Z 19.8N  93.9W    85 KT
 24HR VT     22/1800Z 20.5N  97.1W    95 KT...INLAND
 36HR VT     23/0600Z 21.0N 100.5W    30 KT...INLAND
 48HR VT     23/1800Z...DISSIPATED
 
$$
FORECASTER FRANKLIN
 

WTNT44 KNHC 220234
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  36
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT TUE AUG 21 2007
 
DEAN APPEARS TO BE DEVELOPING A LARGE RAGGED EYE ON SATELLITE
IMAGERY. AN AIR FORCE PLANE REACHED DEAN AND MEASURED A MINIMUM
PRESSURE OF 979 MB AND FLIGHT LEVEL WINDS OF 84 KNOTS.
HOWEVER...THE SFMR HAS ONLY MEASURED 59 KNOTS SO FAR.  SINCE DEEP
CONVECTION IS RETURNING...THE INITIAL INTENSITY IS KEPT AT 70
KNOTS...WHICH IS A BLEND OF BOTH MEASUREMENTS AND DVORAK T-NUMBERS.
DEAN IS FORECAST TO RESTRENGTHEN BEFORE LANDFALL BUT IS RUNNING OUT
OF TIME TO BECOME A MAJOR HURRICANE.  AFTER LANDFALL...THE SURFACE
CIRCULATION SHOULD RAPIDLY BECOME DISRUPTED OVER THE HIGH TERRAIN
OF CENTRAL MEXICO...ALTHOUGH MOISTURE FROM DEAN COULD SPREAD
NORTHWARD.
 
DEAN IS MOVING TOWARD THE WEST-NORTHWEST OR 285 DEGREES AT 16 KNOTS
AROUND THE PERIPHERY OF A STRONG HIGH PRESSURE SYSTEM. THIS GENERAL
MOTION IS EXPECTED TO CONTINUE UNTIL LANDFALL SINCE THE STEERING
CURRENTS ARE NOT FORECAST TO CHANGE.
 
THE MEXICAN NAVY AUTOMATIC STATION LOCATED AT CAYO ARCAS RECENTLY
MEASURED SUSTAINED WINDS OF 46 KNOTS...GUSTS TO 63 KNOTS AND A
MINIMUM PRESSURE OF 986.3 MB. NOAA BUOY 42055 IN THE SOUTHWESTERN
GULF OF MEXICO MEASURED SUSTAINED WINDS OF 38 KNOTS AND A GUST TO
43 KNOTS.  

  
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0300Z 19.9N  93.0W    70 KT
 12HR VT     22/1200Z 20.7N  95.6W    85 KT
 24HR VT     23/0000Z 21.4N  99.0W    40 KT...INLAND
 36HR VT     23/1200Z 22.0N 102.0W    25 KT...INLAND
 48HR VT     24/0000Z...DISSIPATED
 
$$
FORECASTER AVILA
 

WTNT44 KNHC 220832
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  37
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 AM EDT WED AUG 22 2007
 
REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INDICATE
THAT THE CENTRAL CORE OF DEAN COLLAPSED DURING PASSAGE ACROSS THE
YUCATAN PENINSULA.  THE AIRCRAFT FOUND THE RADIUS OF MAXIMUM WINDS
HAD EXPANDED TO 55 N MI IN ASSOCIATION WITH A LARGE CONVECTIVE
BAND.  SATELLITE IMAGERY SHOWS CONVECTION FORMING CLOSE TO THE
CIRCULATION CENTER...BUT THIS DOES NOT CORRESPOND WITH ANY WIND
MAXIMUM SEEN BY THE AIRCRAFT.  THE MINIMUM CENTRAL PRESSURE WAS 979
MB AND THE MAXIMUM SURFACE WINDS FROM THE STEPPED FREQUENCY
MICROWAVE RADIOMETER WERE 64 KT.  BASED ON THIS AND THE POSSIBILITY
THE MAXIMUM WINDS WERE NOT SAMPLED...THE INITIAL INTENSITY REMAINS
70 KT.
 
THE INITIAL MOTION IS 285/17.  A DEEP-LAYER RIDGE NORTH AND
NORTHEAST OF DEAN SHOULD STEER THE CYCLONE GENERALLY
WEST-NORTHWESTWARD UNTIL LANDFALL IN ABOUT 12 HR...AND UNTIL
EVENTUAL DISSIPATION OVER THE MOUNTAINS OF MEXICO.
 
UPPER-LEVEL WINDS HAVE BECOME SOMEWHAT LESS FAVORABLE FOR
INTENSIFICATION...WITH THE SHIPS MODEL AND ANALYSES FROM CIMSS AT
THE UNIVERSITY OF WISCONSIN SHOWING 15-20 KT OF NORTHEASTERLY
VERTICAL WIND SHEAR.  THIS...COMBINED WITH THE LARGE CORE
SIZE...SUGGESTS THAT RE-INTENSIFICATION MAY BE SLOWER THAN
PREVIOUSLY THOUGHT.  THE INTENSITY FORECAST NOW CALLS FOR WINDS TO
INCREASE TO 80 KT BEFORE LANDFALL...WHICH IS A LITTLE ABOVE MOST OF
THE GUIDANCE.  DEAN SHOULD WEAKEN AFTER LANDFALL AND DISSIPATE BY
48 HR AT THE LATEST.
 
THE WIND RADII HAVE BEEN CHANGED SIGNIFICANTLY BASED ON AIRCRAFT...
BUOY...AND QUIKSCAT OBSERVATIONS.  THE INCREASED AREA OF HURRICANE
FORCE WINDS HAS REQUIRED A NORTHWARD EXTENSION OF THE HURRICANE
WARNING ALONG THE MEXICAN COAST. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/0900Z 20.3N  94.8W    70 KT
 12HR VT     22/1800Z 20.9N  97.1W    80 KT
 24HR VT     23/0600Z 21.4N 100.2W    40 KT...INLAND
 36HR VT     23/1800Z 21.8N 103.5W    20 KT...INLAND
 48HR VT     24/0600Z...DISSIPATED
 
$$
FORECASTER BEVEN
 

WTNT44 KNHC 221439
TCDAT4
HURRICANE DEAN DISCUSSION NUMBER  38
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 AM EDT WED AUG 22 2007
 
AN AIR FORCE RESERVE UNIT RECONNAISSANCE AIRCRAFT INVESTIGATING DEAN
IS FINDING FLIGHT LEVEL WINDS OF CLOSE TO 100 KT...AND RECENT
OBSERVATIONS ARE SHOWING A CONTRACTION OF THE INNER CORE WIND
FIELD.  A DROPSONDE ABOUT 20 NMI NORTH OF THE CENTER RECENTLY
REPORTED A WL150...I.E. LOW-LEVEL...MEAN WIND OF 100 KT...
CORRESPONDING TO 85 KT AT THE SURFACE.  ON THIS BASIS...THE
ADVISORY INTENSITY IS INCREASED TO 85 KT...MAKING DEAN A CATEGORY
TWO HURRICANE.  FORTUNATELY...THESE CHANGES IN THE CORE STRUCTURE
ARE OCCURRING TOO CLOSE TO LANDFALL TO ALLOW FOR MUCH FURTHER
INTENSIFICATION. 

THE INITIAL MOTION IS ABOUT THE SAME...285/16. THERE HAS BEEN NO
CHANGE IN THE TRACK FORECAST THINKING...AND DEAN IS EXPECTED TO
MAKE LANDFALL WITHIN THE NEXT FEW HOURS NEAR TUXPAN. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/1500Z 20.6N  96.3W    85 KT
 12HR VT     23/0000Z 21.2N  98.6W    65 KT...INLAND
 24HR VT     23/1200Z 21.3N 101.6W    25 KT...INLAND
 36HR VT     24/0000Z...DISSIPATED
 
$$
FORECASTER FRANKLIN/MAINELLI
 

WTNT44 KNHC 222031
TCDAT4
TROPICAL STORM DEAN DISCUSSION NUMBER  39
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
500 PM EDT WED AUG 22 2007
 
AROUND 1630 UTC...THE CENTER OF DEAN MADE LANDFALL IN MEXICO AS A
CATEGORY TWO HURRICANE NEAR THE TOWN OF TECOLUTLA...ABOUT 40 MILES
SOUTH-SOUTHEAST OF TUXPAN MEXICO.  

ALTHOUGH DEAN CONTINUES TO GENERATE DEEP CONVECTION...THE OVERALL
CLOUD PATTERN HAS DETERIORATED.  THE INITIAL ADVISORY INTENSITY IS
SET AT 60 KT.  HOWEVER...STRONGER WINDS...ESPECIALLY IN GUSTS...ARE
LIKELY OVER ELEVATED TERRAIN.  THE INITIAL MOTION IS 270/15.  DEAN
IS EXPECTED TO CONTINUE TO MOVE WESTWARD AND THE SURFACE
CIRCULATION SHOULD DISSIPATE LATE TONIGHT OR EARLY THURSDAY.
 
THE PRIMARY THREAT IS RAINFALL AND THE POSSIBILITY OF LIFE-
THREATENING FLASH FLOODS AND MUDSLIDES ACROSS PORTIONS OF SOUTHERN
AND CENTRAL MEXICO. 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      22/2100Z 20.5N  98.1W    60 KT...INLAND
 12HR VT     23/0600Z 20.5N 100.5W    30 KT...INLAND
 24HR VT     23/1800Z...DISSIPATED
 
$$
FORECASTER MAINELLI/FRANKLIN
 

WTNT44 KNHC 230222
TCDAT4
TROPICAL DEPRESSION DEAN DISCUSSION NUMBER  40
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL042007
1100 PM EDT WED AUG 22 2007
 
THE HIGH TERRAIN OF MEXICO HAS TAKEN ITS TOLL ON DEAN. SURFACE
OBSERVATIONS AND SATELLITE IMAGES INDICATE THAT THE CYCLONE IS
RAPIDLY WEAKENING AND IS BECOMING A BROAD AREA OF LOW PRESSURE. 
THE DEPRESSION IS MOVING WESTWARD AT ABOUT 17 KNOTS ACROSS MEXICO
BUT STILL PRODUCING TORRENTIAL RAINS.  ANY REMNANT CIRCULATION OF
THE SYSTEM WILL LIKELY DISSIPATE IN ABOUT 12 HOURS OR SO.

THE MID-LEVEL CENTER APPEARS TO BE MOVING WESTWARD A LITTLE
FASTER...AND WILL CONTINUE TO BE CLOSELY MONITORED IN CASE
REGENERATION OCCURS IN THE EASTERN PACIFIC. 

THIS WILL BE THE LAST ADVISORY ON WHAT WAS ONCE CATEGORY FIVE
HURRICANE DEAN. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      23/0300Z 20.5N 100.0W    30 KT
 12HR VT     23/1200Z 20.5N 103.0W    20 KT...REMNANT LOW
 24HR VT     24/0000Z...DISSIPATED
 
$$
FORECASTER AVILA
 

