WTNT43 KNHC 252206
TCDAT3
TROPICAL DEPRESSION THIRTEEN SPECIAL DISCUSSION NUMBER   1
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL132007
615 PM EDT TUE SEP 25 2007
 
DATA FROM AN AIR FORCE RECONNAISSANCE AIRCRAFT SHOW THAT THE AREA OF
LOW PRESSURE IN THE SOUTHWESTERN GULF OF MEXICO HAS A WELL-DEFINED
CIRCULATION.  CONVECTION ASSOCIATED WITH THE CENTER HAS COME IN
PULSES...WITH SUFFICIENT REGULARITY FOR THE LOW TO QUALIFY AS A
TROPICAL DEPRESSION.  THE INITIAL INTENSITY OF 25 KT IS BASED ON
MAXIMUM FLIGHT-LEVEL WINDS OF 29 KT IN THE SOUTHWEST QUADRANT.

THE AIRCRAFT FIXES HAVE BEEN JUMPING AROUND A BIT...BUT A
LONGER-TERM MOTION ESTIMATE IS 220/3.  THE DEPRESSION IS IN A WEAK
STEERING ENVIRONMENT...AND LITTLE OVERALL MOTION IS EXPECTED FOR
THE NEXT DAY OR TWO.  AFTER THAT...GLOBAL MODELS SUGGEST THAT
MID-LEVEL HIGH PRESSURE WILL BUILD OVER THE CENTRAL GULF...AND THIS
PATTERN SHOULD BEGIN TO NUDGE THE CYCLONE TO THE SOUTHWEST.

THERE IS STILL SOME SOUTHWESTERLY SHEAR OVER THE CYCLONE ASSOCIATED
WITH AN UPPER LOW ALONG THE MEXICAN COAST NEAR TAMPICO.  THIS SHEAR
IS EXPECTED TO RELAX AND BE REPLACED BY AN UPPER ANTICYCLONE OVER
THE NEXT COUPLE OF DAYS...WHICH WOULD ALLOW THE SYSTEM AN
OPPORTUNITY TO STRENGTHEN.  NONE OF THE DYNAMICAL MODELS...
INCLUDING THE HWRF AND GFDL...SHOW MUCH DEVELOPMENT...ALTHOUGH THE
STATISTICAL SHIPS MODEL TAKES THE SYSTEM TO NEAR HURRICANE STRENGTH
IN THREE DAYS.  THE OFFICIAL FORECAST BLENDS THIS GUIDANCE BUT IS
CLOSER TO THE SHIPS SOLUTION. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      25/2215Z 21.7N  95.0W    25 KT
 12HR VT     26/0600Z 21.4N  95.0W    30 KT
 24HR VT     26/1800Z 21.2N  95.0W    35 KT
 36HR VT     27/0600Z 21.0N  95.0W    40 KT
 48HR VT     27/1800Z 20.8N  95.1W    45 KT
 72HR VT     28/1800Z 20.5N  95.5W    55 KT
 96HR VT     29/1800Z 20.0N  97.0W    50 KT...INLAND
120HR VT     30/1800Z...DISSIPATED
 
$$
FORECASTER FRANKLIN
 

WTNT43 KNHC 260246
TCDAT3
TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER   2
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL132007
1100 PM EDT TUE SEP 25 2007
 
THE CENTER OF THE DEPRESSION IS DIFFICULT TO LOCATE IN CONVENTIONAL
IMAGERY...BUT AN SSMI MICROWAVE PASS JUST BEFORE 00Z DEPICTED THE
SMALL CENTER NICELY AND INDICATES THAT THE INITIAL MOTION IS 260/4. 
STEERING CURRENTS ARE WEAK...AND LITTLE OVERALL MOTION IS EXPECTED
OVER THE NEXT DAY OR TWO.  SOME OF THE MODELS ROTATE THE DEPRESSION
WITHIN A BROADER LOW-LEVEL CYCLONIC FLOW IN THE SOUTHWESTERN GULF
UNTIL MID-LEVEL RIDGING DEVELOPS OVER THE CENTRAL GULF IN A COUPLE
OF DAYS.  GIVEN THE INTERMITTENT NATURE OF THE CONVECTION...AND
GLOBAL MODEL GUIDANCE SUGGESTING THAT A FAVORABLE UPPER FLOW
PATTERN MAY TAKE A COUPLE DAYS TO DEVELOP...A SHORT-TERM LOOPING
SCENARIO MIGHT BE A REASONABLE ONE.

DEEP CONVECTION HAS BEEN CYCLING TODAY...AND IS PRESENTLY AT A
MINIMUM. THERE IS STILL SOME SOUTHWESTERLY SHEAR OVER THE
DEPRESSION ASSOCIATED WITH AN UPPER LOW ALONG THE MEXICAN COAST
NEAR TAMPICO. THIS SHEAR IS EXPECTED TO RELAX AND BE REPLACED BY AN
UPPER ANTICYCLONE OVER THE NEXT COUPLE OF DAYS...WHICH WOULD ALLOW
THE SYSTEM AN OPPORTUNITY TO STRENGTHEN. HOWEVER...NOT MUCH
DEVELOPMENT IS EXPECTED UNTIL THAT OCCURS. THE LATEST RUN OF THE
GFDL SHOWS A LITTLE MORE DEVELOPMENT THAN THE PREVIOUS RUN AND IS
NOW IN REASONABLE AGREEMENT WITH THE SHIPS GUIDANCE. THE LATEST
OFFICIAL FORECAST STRENGTHENS THE CYCLONE SLIGHTLY LESS QUICKLY
THAN THE PREVIOUS ADVISORY.  


FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/0300Z 21.7N  95.4W    25 KT
 12HR VT     26/1200Z 21.5N  95.5W    25 KT
 24HR VT     27/0000Z 21.3N  95.4W    30 KT
 36HR VT     27/1200Z 21.1N  95.3W    35 KT
 48HR VT     28/0000Z 20.9N  95.6W    40 KT
 72HR VT     29/0000Z 20.5N  96.5W    50 KT
 96HR VT     30/0000Z 20.0N  98.0W    30 KT...INLAND
120HR VT     01/0000Z...DISSIPATED
 
$$
FORECASTER FRANKLIN
 

WTNT43 KNHC 260838
TCDAT3
TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER   3
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL132007
500 AM EDT WED SEP 26 2007
 
AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INVESTIGATING
TROPICAL DEPRESSION THIRTEEN REPORTED MAXIMUM WINDS OF 26 KT AT A
FLIGHT LEVEL OF 1500 FT...ALONG WITH A CENTRAL PRESSURE OF
1007-1008 MB.  SATELLITE IMAGERY SHOWS AN INCREASE ON CONVECTION
EAST OF THE CENTER DURING THE PAST FEW HOURS...WHICH HAS RESULTED IN
SATELLITE INTENSITY ESTIMATES OF 30 KT FROM TAFB AND SAB.  BASED ON
THE AIRCRAFT DATA...THE INITIAL INTENSITY REMAINS 25 KT. 

THE HURRICANE HUNTER FOUND THE CENTER ABOUT 40 NM MI SOUTH-SOUTHEAST 
OF THE PREVIOUS ADVISORY POSITION...AND IT IS UNCLEAR HOW MUCH OF
THIS IS MOTION AND HOW MUCH IS REFORMATION OF THE CENTER.  THE
INITIAL MOTION IS A RATHER UNCERTAIN 180/3.  ALL MODEL GUIDANCE
AGREES THAT THE CYCLONE SHOULD MOVE LITTLE DURING THE NEXT 12-24
HR...WITH PERHAPS SOME SMALL-SCALE LOOPING OF THE CENTER.  AFTER
THAT...A MID-LEVEL RIDGE BUILDING EASTWARD FROM NORTHERN MEXICO
SHOULD STEER THE DEPRESSION TOWARD THE COAST OF MEXICO.  THE GFS
AND EUROPEAN MODELS SHOW A SOUTHWARD MOTION...WHILE THE UKMET AND
HWRF MODELS SHOW A WESTWARD MOTION.  THE NEW FORECAST TRACK
COMPROMISES BETWEEN THESE EXTREMES BY SHOWING A WEST-SOUTHWESTWARD
MOTION AFTER 24 HR...WITH THE CENTER REACHING THE COAST OF MEXICO
IN ABOUT 48 HR...ABOUT A DAY EARLIER THAN PREVIOUSLY FORECAST.  THE
NEW TRACK IS SHIFTED SOUTH OF THE PREVIOUS TRACK BASED MAINLY ON
THE INITIAL POSITION.

WATER VAPOR IMAGERY SHOWS AN UPPER-LEVEL LOW CENTERED NEAR TUXPAN
MEXICO.  THE LARGE-SCALE MODELS FORECAST THIS FEATURE TO MOVE
SOUTHWARD OR SOUTHWESTWARD AWAY FROM THE DEPRESSION...ALLOWING AN
UPPER-LEVEL ANTICYCLONE TO BUILD OVER THE SYSTEM WITH LIGHT
VERTICAL SHEAR.  THIS EVOLUTION SHOULD ALLOW THE DEPRESSION TO
STRENGTHEN UNTIL IT MAKES LANDFALL....AND THE INTENSITY FORECAST
THUS CALLS FOR STEADY STRENGTHENING TO 45 KT IN AGREEMENT WITH THE
SHIPS MODEL.  SHOULD THE DEPRESSION STAY OFFSHORE LONGER THAN
CURRENTLY FORECAST...IT COULD GET STRONGER THAN 45 KT BEFORE LAND.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/0900Z 21.0N  95.0W    25 KT
 12HR VT     26/1800Z 20.8N  94.9W    30 KT
 24HR VT     27/0600Z 20.6N  94.9W    35 KT
 36HR VT     27/1800Z 20.3N  95.7W    40 KT
 48HR VT     28/0600Z 20.1N  96.6W    45 KT
 72HR VT     29/0600Z 20.0N  98.0W    25 KT...INLAND
 96HR VT     30/0600Z...DISSIPATED
 
$$
FORECASTER BEVEN
 

WTNT43 KNHC 261445
TCDAT3
TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER   4
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL132007
1100 AM EDT WED SEP 26 2007

THERE HAS BEEN AN INCREASE IN DEEP CONVECTION AND ORGANIZATION OF
THE DEPRESSION'S CLOUD PATTERN OVER THE PAST SEVERAL HOURS.  DVORAK
SATELLITE CLASSIFICATIONS FROM TAFB AND SAB ARE AT 30 AND 35 KT
RESPECTIVELY.  WE WILL WAIT FOR THE NEXT AIR FORCE HURRICANE HUNTER
FIX SCHEDULED FOR 1800 UTC TO SEE IF THE SYSTEM HAS INDEED
STRENGTHENED INTO A TROPICAL STORM.  AN UPPER-LEVEL CYCLONE IN THE
VICINITY OF TUXPAN MEXICO IS MOVING SOUTHWESTWARD...AND AWAY FROM
THE TROPICAL CYCLONE...CREATING AN ENVIRONMENT THAT IS MORE
FAVORABLE FOR STRENGTHENING.  CIRRUS MOTIONS SHOW THAT THE
ANTICYCLONIC OUTFLOW IS BECOMING BETTER ESTABLISHED OVER THE
SYSTEM.  THE OFFICIAL INTENSITY FORECAST...WHICH IS SIMILAR TO THE
SHIPS AND GFDL GUIDANCE...COULD BE CONSERVATIVE...PARTICULARLY IF
THE TROPICAL CYCLONE REMAINS OVER WATER LONGER THAN EXPECTED.

THE INITIAL MOTION IS AN UNCERTAIN 180/2.  A WEAK STEERING CURRENT
HAS PREVAILED OVER THE SOUTHWESTERN GULF OF MEXICO OVER THE PAST
COUPLE OF DAYS...AND THE DEPRESSION WILL PROBABLY MOVE QUITE SLOWLY
AND ERRATICALLY TODAY.  GLOBAL MODELS FORECAST A WEAK MID-LEVEL
RIDGE TO BUILD EASTWARD SLOWLY FROM NORTHERN MEXICO OVER THE GULF
OF MEXICO.  THIS SHOULD EVENTUALLY RESULT IN A SOUTHWESTWARD TO
WESTWARD MOTION OF THE TROPICAL CYCLONE TOWARD THE COAST OF MEXICO.  
ALTHOUGH THE CONSENSUS OF THE TRACK GUIDANCE MODELS INDICATES THE
ABOVEMENTIONED MOTION...THERE ARE SIGNIFICANT DIFFERENCES AMONGST
THE INDIVIDUAL MODELS.  IT SHOULD BE NOTED... HOWEVER...THAT ALL OF
THE DYNAMICAL MODELS KEEP THE SYSTEM OFFSHORE THROUGH 36 HOURS. 
THE OFFICIAL FORECAST FOLLOWS THE CONSENSUS AND IS SIMILAR TO THE
TRACK FORECAST FROM THE PREVIOUS NHC PACKAGE.

A TROPICAL STORM WATCH WILL LIKELY BE REQUIRED FOR A PORTION OF THE
GULF COAST OF MEXICO LATER TODAY.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/1500Z 20.9N  95.0W    30 KT
 12HR VT     27/0000Z 20.7N  95.1W    35 KT
 24HR VT     27/1200Z 20.5N  95.4W    40 KT
 36HR VT     28/0000Z 20.3N  95.9W    45 KT
 48HR VT     28/1200Z 20.1N  96.6W    50 KT
 72HR VT     29/1200Z 20.0N  97.7W    20 KT...INLAND
 96HR VT     30/1200Z...DISSIPATED
 
$$
FORECASTER PASCH
 

WTNT43 KNHC 262034
TCDAT3
TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER   5
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL132007
500 PM EDT WED SEP 26 2007

THE CYCLONE'S CLOUD PATTERN IS WELL-ORGANIZED WITH DISTINCT BANDING
FEATURES OVER THE SOUTHERN SEMICIRCLE AND A FAIRLY SYMMETRIC
UPPER-LEVEL OUTFLOW.  SATELLITE-BASED INTENSITY ESTIMATES FROM TAFB
AND SAB ARE BOTH AT TROPICAL STORM STRENGTH.  HOWEVER...LOOKS CAN
BE DECEIVING...AND RECENT DATA FROM AN AIR FORCE HURRICANE HUNTER
MISSION INDICATE THAT THE SYSTEM IS NOT YET A TROPICAL STORM.  THE
ADVISORY INTENSITY REMAINS 30 KT...AND THIS MAY BE A GENEROUS
ESTIMATE SINCE THE HIGHEST FLIGHT-LEVEL WINDS WERE ONLY 29 KT. 
GIVEN THE ORGANIZATION OF THE SYSTEM...DECREASING SHEAR...AND VERY
WARM WATERS...STRENGTHENING IS LIKELY.  THE OFFICIAL WIND SPEED
FORECAST IS SIMILAR TO THE SHIPS GUIDANCE...AND COULD BE
CONSERVATIVE.

AIRCRAFT FIXES INDICATE THAT THE CYCLONE IS MEANDERING OR MAY BE
EXECUTING A COUNTERCLOCKWISE LOOP.  THE TRACK FORECAST REASONING IS
ABOUT THE SAME AS EARLIER TODAY.  A MID-TROPOSPHERIC RIDGE IS
EXPECTED TO BUILD EASTWARD GRADUALLY FROM NORTHERN MEXICO INTO THE
GULF OVER THE NEXT FEW DAYS.  THIS SHOULD EVENTUALLY STEER THE
TROPICAL CYCLONE IN A GENERALLY WESTWARD DIRECTION TOWARD THE COAST
OF MEXICO.  HOWEVER THE MODELS ARE NOT IN VERY GOOD AGREMMENT.  THE
U.K. MET. OFFICE MODEL TRACK IS ON THE NORTH SIDE OF THE GUIDANCE
SUITE WITH A WEST-NORTHWESTWARD MOTION ACROSS THE COAST IN ABOUT 66
HOURS.  THE HWRF MODEL KEEPS THE SYSTEM MEANDERING OFFSHORE AND
WEAKENS IT LATE IN THE FORECAST PERIOD.  THE GFDL MODEL SHOWS
LANDFALL IN ABOUT 36 HOURS...IN CONTRAST TO THE MUCH SLOWER ECMWF
WHICH DOES NOT SHOW THE CYCLONE CROSSING THE COASTLINE UNTIL NEARLY
84 HOURS.  THE OFFICIAL FORECAST IS ABOUT IN THE MIDDLE OF THESE
VARIOUS OBJECTIVE TRACKS.

THE MEANDERING MOTION DELAYS THE ISSUANCE OF A TROPICAL STORM WATCH
FOR THE GULF COAST OF MEXICO A LITTLE MORE...BUT THE WATCH COULD BE
ISSUED LATER TONIGHT OR EARLY TOMORROW. 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      26/2100Z 21.3N  94.5W    30 KT
 12HR VT     27/0600Z 21.2N  94.8W    35 KT
 24HR VT     27/1800Z 20.9N  95.1W    45 KT
 36HR VT     28/0600Z 20.7N  95.6W    50 KT
 48HR VT     28/1800Z 20.5N  96.3W    55 KT
 72HR VT     29/1800Z 20.2N  97.8W    20 KT...INLAND
 96HR VT     30/1800Z...DISSIPATED
 
$$
FORECASTER PASCH
 

WTNT43 KNHC 270249
TCDAT3
TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER   6
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL132007
1100 PM EDT WED SEP 26 2007
 
THE SATELLITE PRESENTATION OF THE DEPRESSION HAS DEGRADED THIS
EVENING...WITH A PARTIALLY EXPOSED CENTER TO THE NORTHEAST OF A
SMALL BAND OF MODEST CONVECTION.  DVORAK T-NUMBERS FROM BOTH TAFB
AND SAB HAVE DECREASED.  THE INITIAL INTENSITY WILL BE HELD AT 30
KT PENDING THE ARRIVAL OF THE NEXT RECONNAISSANCE AIRCRAFT AT 06Z.

THE DEPRESSION APPEARS TO HAVE COMPLETED A SMALL LOOP...AND THE
INITIAL MOTION IS ESTIMATED TO BE 260/3...BASED MAINLY ON A 2315Z
MICROWAVE PASS.  THERE HAS BEEN A BIT OF A NORTHWARD SHIFT IN THE
MODEL GUIDANCE THIS EVENING.  THE MID-LEVEL RIDGE THAT IS FORECAST
TO BUILD EASTWARD FROM NORTHERN MEXICO HAS SHIFTED A LITTLE FARTHER
EASTWARD IN THE MODEL RUNS...WHICH ALLOWS THE DEPRESSION TO ACQUIRE
SOME NORTHWARD COMPONENT OF MOTION AS IT APPROACHES THE COAST.  THE
OFFICIAL FORECAST HAS BEEN SHIFTED NORTHWARD...AND IS IN BEST
AGREEMENT WITH THE GFS.  NEARLY ALL THE OTHER GUIDANCE MODELS ARE
EVEN FARTHER NORTH.

THE UPPER-LEVEL FLOW OVER THE DEPRESSION IS ANTICYCLONIC AND
DIFLUENT...AND IT IS A LITTLE SURPRISING THAT THE SYSTEM HAS NOT
STRENGTHENED YET.  THE UPPER-FLOW IS FORECAST TO REMAIN FAVORABLE
FOR DEVELOPMENT...SO PERHAPS IT IS JUST A MATTER OF TIME.  THE
OFFICIAL FORECAST REMAINS CLOSE TO THE SHIPS GUIDANCE...WITH THE
GFDL AND HWRF FORECASTING A LITTLE LESS DEVELOPMENT BUT STILL
MAKING THE SYSTEM A TROPICAL STORM.

THE NEW FORECAST BRINGS TROPICAL STORM FORCE WINDS VERY CLOSE TO THE
MEXICAN COAST IN 36 HOURS...NECESSITATING A TROPICAL STORM WATCH AT
THIS TIME.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/0300Z 21.2N  94.8W    30 KT
 12HR VT     27/1200Z 21.1N  95.0W    35 KT
 24HR VT     28/0000Z 20.9N  95.5W    45 KT
 36HR VT     28/1200Z 20.9N  96.3W    50 KT
 48HR VT     29/0000Z 21.0N  97.5W    55 KT...INLAND
 72HR VT     30/0000Z 21.5N  99.5W    20 KT...INLAND
 96HR VT     01/0000Z...DISSIPATED
 
$$
FORECASTER FRANKLIN
 

WTNT43 KNHC 270842
TCDAT3
TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER   7
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL132007
500 AM EDT THU SEP 27 2007
 
REPORTS FROM AN AIR FORCE RESERVE HURRICANE HUNTER INVESTIGATING
TROPICAL DEPRESSION THIRTEEN INCLUDED A 1500 FT FLIGHT-LEVEL WIND
OF 36 KT IN THE NORTHEASTERN QUADRANT AND A CENTRAL PRESSURE OF
1008 MB.  SATELLITE IMAGERY AND DATA FROM THE MEXICAN RADAR AT
ALVARADO SHOW INCREASING CONVECTION IN THE SOUTHWESTERN
SEMICIRCLE...ALTHOUGH THE BANDING IS NOT WELL DEFINED.  BASED ON
THE AIRCRAFT DATA...THE INITIAL INTENSITY REMAINS 30 KT.

THE AIRCRAFT FOUND THE DEPRESSION SOUTH OF THE PREVIOUS ADVISORY
POSITION...WHILE THE THREE FIXES FROM THE MISSION SUGGEST A
WESTERLY MOTION.  PUTTING THESE TOGETHER YIELDS AN UNCERTAIN MOTION
ESTIMATE OF 245/3.  WATER VAPOR IMAGERY AND RAWINSONDE DATA SHOW
THAT THE MID/LEVEL RIDGE OVER NORTHERN MEXICO IS BUILDING EASTWARD
OVER THE GULF OF MEXICO...WHICH SHOULD STEER THE DEPRESSION
GENERALLY WESTWARD INTO SOUTHEASTERN MEXICO DURING THE NEXT 2-3
DAYS.  THE SPREAD OF THE TRACK GUIDANCE HAS DECREASED SINCE LAST
NIGHT...WITH THE MODELS NOW SPREAD BETWEEN THE WEST-SOUTHWESTWARD
TRACK GFS AND THE WEST-NORTHWESTWARD TRACKING UKMET.  THE NEW
FORECAST TRACK CALLS FOR A GENERALLY WESTWARD MOTION WITH LANDFALL
ON THE COAST OF MEXICO IN ABOUT 36 HR.  IT LIES A LITTLE SOUTH OF
THE PREVIOUS TRACK DUE TO THE INITIAL POSITION.
 
THE DEPRESSION IS UNDER AN UPPER-LEVEL ANTICYCLONE...ALTHOUGH WATER
VAPOR IMAGERY AND MODEL ANALYSES SUGGEST SOME NORTHEASTERLY
UPPER-LEVEL FLOW AND DRY AIR MAY BE TEMPORARILY UNDERCUTTING THE
ANTICYCLONE.  THE MODELS FORECAST THIS FLOW TO DECREASE...LEAVING
THE DEPRESSION IN CONDITIONS FAVORABLE FOR STRENGTHENING.  THE
INTENSITY FORECAST CALLS FOR THE CYCLONE TO REACH 50 KT AT LANDFALL
IN GOOD AGREEMENT WITH THE SHIPS AND HWRF MODELS.  THE CYCLONE
SHOULD WEAKEN AFTER LANDFALL AND DISSIPATE OVER THE MOUNTAINS OF
MEXICO BY 72 HR.

TROPICAL STORM WARNINGS COULD BE REQUIRED FOR PORTIONS OF THE GULF
COAST OF MEXICO LATER TODAY.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/0900Z 20.8N  95.1W    30 KT
 12HR VT     27/1800Z 20.7N  95.4W    35 KT
 24HR VT     28/0600Z 20.6N  96.0W    45 KT
 36HR VT     28/1800Z 20.6N  97.1W    50 KT
 48HR VT     29/0600Z 20.9N  98.7W    30 KT...INLAND
 72HR VT     30/0600Z...DISSIPATED
 
$$
FORECASTER BEVEN
 

WTNT43 KNHC 271438
TCDAT3
TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER   8
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL132007
1100 AM EDT THU SEP 27 2007
 
DATA FROM THE ALVARADO RADAR IN MEXICO SHOW A WELL-DEFINED
CIRCULATION AND SATELLITE IMAGES SHOW AN AREA OF DEEP CONVECTION
NEAR THE CENTER.  T-NUMBERS HAVE NOT CHANGED SIGNIFICANTLY... 
SUGGESTING THAT THE INITIAL INTENSITY REMAINS AT 30 KNOTS.  THE
DEPRESSION IS MOVING OVER WARM WATERS AND THE SHEAR IS EXPECTED TO
STAY LOW...SO THE DEPRESSION COULD BECOME A TROPICAL STORM AT
ANY TIME.   MOST OF THE INTENSITY MODELS ALSO SUGGEST THAT THE
DEPRESSION WILL REACH THE COAST OF MEXICO AS A STRENGTHENING
TROPICAL STORM AND SO DOES THE OFFICIAL FORECAST.  AN AIR FORCE
RESERVE HURRICANE HUNTER PLANE WILL BE IN THE DEPRESSION AROUND
18Z.
 
THE DEPRESSION HAS MOVED VERY LITTLE DURING THE PAST FEW HOURS AND
REMAINS TRAPPED SOUTH OF A NARROW MID-LEVEL RIDGE OVER THE
NORTHERN GULF OF MEXICO. THIS PATTERN IS EXPECTED TO PERSIST FOR
THE NEXT DAY OR TWO...FORCING THE TROPICAL CYCLONE TO DRIFT TOWARD
THE WEST OR WEST-SOUTHWEST OVER THE SOUTHWESTERN GULF OF MEXICO. 
THIS IS CONSISTENT WITH MOST OF THE TRACK GUIDANCE WHICH SHOWS A
SLOW WESTWARD DRIFT OF THE CYCLONE TOWARD THE COAST OF MEXICO.
 
THIS SLOW-MOVING SYSTEM WILL PROBABLY PRODUCE TORRENTIAL RAINS
PRIMARILY OVER THE STATE OF VERACRUZ.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      27/1500Z 20.7N  95.2W    30 KT
 12HR VT     28/0000Z 20.4N  95.8W    35 KT
 24HR VT     28/1200Z 20.3N  96.7W    45 KT
 36HR VT     29/0000Z 20.5N  97.5W    25 KT...INLAND
 48HR VT     29/1200Z 21.0N  99.0W    20 KT...REMNANT LOW
 72HR VT     30/1200Z...DISSIPATED
 
$$
FORECASTER AVILA
 

