WTNT41 KNHC 290014
TCDAT1
 
TROPICAL STORM ARLENE SPECIAL DISCUSSION NUMBER   1
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012011
700 PM CDT TUE JUN 28 2011
 
DURING THE PAST FEW HOURS...THERE HAS BEEN AN INCREASE IN THE
COVERAGE AND ORGANIZATION OF THE DEEP CONVECTION IN ASSOCIATION
WITH THE LOW PRESSURE AREA IN THE SOUTHWESTERN GULF OF MEXICO. 
DATA T-NUMBERS FROM SPECIAL DVORAK CLASSIFICATIONS AT 2245 UTC FROM
SAB AND TAFB WERE 2.5 AND 2.0...RESPECTIVELY.  THE HURRICANE HUNTER
AIRCRAFT INVESTIGATING THE SYSTEM THIS AFTERNOON ALREADY FOUND AN
AREA OF 30 TO 35 KT SURFACE WINDS TO THE NORTHEAST OF THE 
CENTER.  BASED ON THE EARLIER AIRCRAFT OBSERVATIONS AND RECENT
SATELLITE TRENDS...THE SYSTEM IS UPGRADED TO A TROPICAL STORM...
THE FIRST OF THE 2011 ATLANTIC HURRICANE SEASON.        
 
THE INITIAL MOTION ESTIMATE IS 290/6.  A MID- TO UPPER-LEVEL
WEAKNESS NORTH OF THE TROPICAL CYCLONE IS FORECAST TO LIFT
NORTHEASTWARD DURING THE NEXT 24 HOURS AS A RIDGE OVER THE 
CENTRAL UNTIED STATES BUILDS EASTWARD.  THIS SHOULD CAUSE THE
TRACK OF ARLENE TO BEND TOWARD THE WEST OR WEST-SOUTHWEST.  THE
TRACK GUIDANCE IS IN GOOD AGREEMENT ON THIS SCENARIO AND THE NHC
FORECAST IS NEAR THE MIDDLE OF THE GUIDANCE ENVELOPE.

ENVIRONMENTAL CONDITIONS APPEAR FAVORABLE FOR STRENGTHENING. THE
SHEARING AFFECTS OF THE RETREATING UPPER-LEVEL TROUGH ARE LESSENING
AND THE SHEAR IS EXPECTED TO DECREASE DURING THE NEXT 24 HOURS.
PERHAPS THE ONE LIMITING FACTOR FOR SIGNIFICANT INTENSIFICATION
COULD BE THE BROAD NATURE OF THE CYCLONE CIRCULATION. THE OFFICIAL
INTENSITY FORECAST IS CLOSE TO THE STATISTICAL MODEL OUTPUT.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/0000Z 21.2N  93.7W   35 KT  40 MPH
 12H  29/0600Z 21.7N  94.6W   40 KT  45 MPH
 24H  29/1800Z 22.0N  95.9W   45 KT  50 MPH
 36H  30/0600Z 22.0N  96.9W   50 KT  60 MPH
 48H  30/1800Z 22.0N  97.9W   50 KT  60 MPH
 72H  01/1800Z 21.5N 100.0W   25 KT  30 MPH...INLAND
 96H  02/1800Z...INLAND
 
$$
FORECASTER BROWN/KIMBERLAIN
 

WTNT41 KNHC 290253
TCDAT1
 
TROPICAL STORM ARLENE DISCUSSION NUMBER   2
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012011
1000 PM CDT TUE JUN 28 2011
 
WHILE THE DEEP CONVECTION NEAR AND TO THE NORTHEAST OF THE CENTER OF
ARLENE HAS CONTINUED TO INCREASE DURING THE LAST FEW HOURS...THERE
HAS BEEN NO FURTHER INCREASE IN ITS ORGANIZATION.  DVORAK SATELLITE
INTENSITY ESTIMATES REMAIN UNCHANGED SINCE 0000 UTC...AND THE
INITIAL INTENSITY IS HELD AT 35 KT.  

SATELLITE IMAGERY SUGGESTS THAT UPPER-LEVEL WESTERLY WINDS CONTINUE
TO IMPINGE ON THE CYCLONE...AND UW CIMSS SHEAR ANALYSES INDICATE
ABOUT 20 KT OF WESTERLY SHEAR AFFECTING ARLENE. THE DYNAMICAL MODEL
AND SHIPS GUIDANCE SUGGEST THAT THE SHEAR WILL DECREASE DURING THE
NEXT 24 HOURS WHICH SHOULD ALLOW AN OPPORTUNITY FOR GRADUAL
STRENGTHENING. HOWEVER...THE LARGE CIRCULATION OF THE TROPICAL
CYCLONE AND THE POSSIBILITY OF A SLOWER REDUCTION OF THE WESTERLY
SHEAR COULD LIMIT ITS POTENTIAL FOR SIGNIFICANT INTENSIFICATION
PRIOR TO LANDFALL.   THE OFFICIAL FORECAST IS SIMILAR TO THE
PREVIOUS ADVISORY AND CLOSE TO CONSENSUS OF THE INTENSITY GUIDANCE. 

ARLENE CONTINUES MOVING SLOWLY WEST-NORTHWESTWARD OR 295/6. THE
STORM IS FORECAST TO TURN TOWARD THE WEST ON WEDNESDAY AS A MID- TO
UPPER-LEVEL RIDGE OVER THE CENTRAL UNITED STATES BUILDS EASTWARD. 
SEVERAL OF THE DYNAMICAL MODELS INDICATE THAT ARLENE COULD TURN
WEST-SOUTHWESTWARD AS IT APPROACHES THE COAST OF MEXICO DUE TO THE
STRENGTHENING RIDGE.  THE OFFICIAL TRACK FORECAST SUGGESTS THIS
POSSIBILITY AND LIES BETWEEN THE GFS AND ECMWF MODEL SOLUTIONS. 

GIVEN THE LARGE SIZE OF THE CIRCULATION OF ARLENE...ONE SHOULD NOT
FOCUS ON THE EXACT FORECAST TRACK...AS IMPACTS COULD BE FELT OVER A
LARGE PORTION OF NORTHEASTERN MEXICO WELL AWAY FROM THE CENTER.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/0300Z 21.4N  94.1W   35 KT  40 MPH
 12H  29/1200Z 21.8N  95.1W   40 KT  45 MPH
 24H  30/0000Z 22.0N  96.3W   45 KT  50 MPH
 36H  30/1200Z 21.9N  97.4W   50 KT  60 MPH
 48H  01/0000Z 21.7N  98.6W   35 KT  40 MPH...INLAND
 72H  02/0000Z 21.3N 100.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 96H  03/0000Z...DISSIPATED
 
$$
FORECASTER BROWN/KIMBERLAIN
 

WTNT41 KNHC 290839
TCDAT1
 
TROPICAL STORM ARLENE DISCUSSION NUMBER   3
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012011
400 AM CDT WED JUN 29 2011
 
THUNDERSTORM COVERAGE HAS INCREASED MARKEDLY NEAR AND TO THE
SOUTHEAST OF THE CENTER OF ARLENE DURING THE PAST SEVERAL HOURS. 
HOWEVER...A TRMM MICROWAVE PASS AT 0502 UTC DID NOT SHOW MUCH IN
THE WAY OF ORGANIZATION NEAR THE CENTER...WITH A LACK OF PROMINENT
BANDING. SATELLITE INTENSITY ESTIMATES SUPPORT AN INTENSITY OF
ABOUT 35 KT...SO THAT WILL REMAIN THE INITIAL WIND SPEED.  AN AIR
FORCE RESERVE RECONNAISSANCE AIRCRAFT IS SCHEDULED TO INVESTIGATE
ARLENE LATER THIS MORNING TO PROVIDE MORE INFORMATION ON THE
STRUCTURE AND INTENSITY OF THE CYCLONE. 
 
UPPER-LEVEL CLOUD MOTIONS SUGGEST THAT THE SHEAR IS DECREASING...AND
GIVEN AN INCREASINGLY FAVORABLE ENVIRONMENT...IT SEEMS LIKE IT IS
ONLY A MATTER OF TIME BEFORE ARLENE STRENGTHENS. THE BULK OF THE
INTENSITY GUIDANCE SHOWS THE SYSTEM AS A MODERATE TROPICAL STORM
BEFORE LANDFALL...THOUGH THE HWRF HAS THE SYSTEM BRIEFLY AS A
HURRICANE.  GIVEN THE LARGE SIZE OF ARLENE AND THE LACK OF ANY
INNER CORE FEATURES...HURRICANE STRENGTH APPEARS UNLIKELY...AND THE
NHC FORECAST WILL STAY CLOSE TO THE INTENSITY MODEL CONSENSUS AND
THE PREVIOUS FORECAST.
 
OVERNIGHT MICROWAVE IMAGERY HAS NOT PROVIDED A DEFINITIVE CENTER
POSITION...HOWEVER GEOSTATIONARY IMAGERY SUGGESTS THAT ARLENE IS
STILL MOVING TOWARD THE WEST-NORTHWEST AT ABOUT 7 KT...OR EVEN A
BIT FASTER THAN THAT DURING THE PAST FEW HOURS.  A WESTWARD TURN IS
EXPECTED LATER TODAY AS ARLENE IS STEERED AROUND A STRONG RIDGE
OVER THE SOUTH-CENTRAL UNITED STATES.  THE CYCLONE COULD EVEN MOVE
A LITTLE SOUTH OF WEST TOMORROW DUE TO THE POSITIONING OF THE
RIDGE...AS SUGGESTED BY A FEW GLOBAL MODELS.  THE NEW FORECAST IS
BASICALLY AN UPDATE OF THE PREVIOUS ONE...SHOWING LANDFALL IN A
LITTLE OVER 24 HOURS.
 
GIVEN THE LARGE SIZE OF THE CIRCULATION OF ARLENE...ONE SHOULD NOT
FOCUS ON THE EXACT FORECAST TRACK...AS IMPACTS WILL LIKELY BE FELT
OVER A LARGE PORTION OF NORTHEASTERN MEXICO WELL AWAY FROM THE
CENTER.
 

FORECAST POSITIONS AND MAX WINDS
 
INIT  29/0900Z 21.8N  95.0W   35 KT  40 MPH
 12H  29/1800Z 22.1N  95.9W   40 KT  45 MPH
 24H  30/0600Z 22.1N  97.1W   50 KT  60 MPH
 36H  30/1800Z 22.0N  98.2W   40 KT  45 MPH...INLAND
 48H  01/0600Z 21.8N  99.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
 72H  02/0600Z...DISSIPATED
 
$$
FORECASTER BLAKE/BRENNAN
 

WTNT41 KNHC 291446
TCDAT1
 
TROPICAL STORM ARLENE DISCUSSION NUMBER   4
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012011
1000 AM CDT WED JUN 29 2011
 
THE CLOUD PATTERN OF THE TROPICAL STORM IS GRADUALLY BECOMING BETTER
ORGANIZED THIS MORNING...WITH MORE EVIDENCE OF CONVECTIVE BANDING.
THE CURRENT INTENSITY IS SET AT 45 KT...WHICH IS IN CLOSE AGREEMENT
WITH SFMR-OBSERVED SURFACE WIND MEASUREMENTS FROM THE AIR FORCE
HURRICANE HUNTERS.  WATER VAPOR IMAGERY INDICATES THAT THE
UPPER-LEVEL WINDS ARE BECOMING MORE CONDUCIVE FOR STRENGTHENING.
THE CURRENT LACK OF A WELL-DEFINED INNER CORE WOULD ARGUE AGAINST
SIGNIFICANT STRENGTHENING OVER THE NEXT 24 HOURS.  HOWEVER...THE
SHIPS RAPID INTENSIFICATION INDEX SHOWS A SIGNIFICANTLY HIGH
PROBABILITY OF A 25 TO 30 KT INCREASE IN INTENSITY OVER THE NEXT 24
HOURS.  THEREFORE THE OFFICIAL INTENSITY FORECAST IS ABOVE MOST OF
THE GUIDANCE AND NOW SHOWS ARLENE APPROACHING HURRICANE STRENGTH AT
LANDFALL.  BASED ON THE NEW INTENSITY FORECAST...A HURRICANE WATCH
HAS BEEN ISSUED FOR A PORTION OF THE COAST OF NORTHEASTERN MEXICO.
 
CENTER FIXES FROM THE AIRCRAFT INDICATE THAT ARLENE WAS LOCATED
FARTHER SOUTH THAN PREVIOUSLY ESTIMATED...WHICH REQUIRES SOME
SOUTHWARD RELOCATION FOR THIS ADVISORY.  BASED ON THE LATEST
FIXES...THE INITIAL MOTION ESTIMATE IS NOW WEST OR 270/7.  A
DEEP-LAYER RIDGE TO THE NORTH AND NORTHWEST OF ARLENE SHOULD INDUCE
A WESTWARD OR SLIGHTLY SOUTH OF WESTWARD TRACK FOR THE NEXT DAY OR
TWO.  SOME OF THE MODEL GUIDANCE SUGGESTS EVEN MORE OF A TURN TO
THE LEFT AS THE CENTER NEARS THE COAST.  THE OFFICIAL TRACK
FORECAST IS MORE OR LESS BETWEEN THE GFS AND ECMWF TRACKS.
 
GIVEN THE LARGE SIZE OF THE CIRCULATION OF ARLENE...ONE SHOULD NOT
FOCUS ON THE EXACT FORECAST TRACK...AS IMPACTS WILL LIKELY BE FELT
OVER A LARGE PORTION OF NORTHEASTERN MEXICO WELL AWAY FROM THE
CENTER.
 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/1500Z 21.2N  95.7W   45 KT  50 MPH
 12H  30/0000Z 21.2N  96.6W   50 KT  60 MPH
 24H  30/1200Z 21.2N  97.7W   60 KT  70 MPH...INLAND
 36H  01/0000Z 21.0N  98.8W   35 KT  40 MPH...INLAND
 48H  01/1200Z 20.8N 100.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  02/1200Z...DISSIPATED
 
$$
FORECASTER PASCH/BEVEN
 

WTNT41 KNHC 292035
TCDAT1
 
TROPICAL STORM ARLENE DISCUSSION NUMBER   5
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012011
400 PM CDT WED JUN 29 2011
 
THERE HAS NOT BEEN MUCH CHANGE IN THE ORGANIZATION OF THE CLOUD
PATTERN SINCE THIS MORNING.  MOST OF THE DEEP CONVECTION WAS
OCCURRING OVER THE SOUTHERN PORTION OF THE CIRCULATION...ALTHOUGH  
RECENTLY THERE HAVE BEEN INDICATIONS OF CONVECTIVE BANDS BEGINNING
TO WRAP AROUND THE NORTHEASTERN QUADRANT OF THE STORM.  THE
INTENSITY IS HELD AT 45 KT FOR THIS ADVISORY...WITH ANOTHER
HURRICANE HUNTER MISSION SCHEDULED TO PENETRATE THE CENTER VERY
SOON.  THE SHIPS RAPID INTENSIFICATION INDEX CONTINUES TO SHOW A
SIGNIFICANT PROBABILITY OF A 25 TO 30 KT INCREASE OVER 24
HOURS...HOWEVER INTERACTION WITH LAND WOULD HALT STRENGTHENING
SOONER THAN THAT TIME FRAME.  THE LACK OF A WELL-DEFINED INNER CORE
MITIGATES THE INCREASINGLY CONDUCIVE ATMOSPHERIC ENVIRONMENT FOR
STRENGTHENING.  IT IS POSSIBLE FOR ARLENE TO REACH A PEAK INTENSITY
OF 55-65 KT BETWEEN THE 12 HR FORECAST POINT AND LANDFALL...AND
THUS THE SYSTEM STILL HAS THE POTENTIAL TO BECOME A HURRICANE.

THE ABOVE-MENTIONED SOUTHERN CONVECTIVE ASYMMETRY MAY HAVE PARTIALLY
EXPLAINED THE SOUTHWARD COMPONENT OF MOTION NOTED IN THE AIRCRAFT
FIXES FROM EARLIER TODAY.  A LONGER-TERM...AND LIKELY MORE
REPRESENTATIVE...MOTION ESTIMATE IS NOW ABOUT 270/6.  A STRONG
MID-TROPOSPHERIC HIGH PRESSURE AREA TO THE NORTH AND NORTHWEST OF
ARLENE SHOULD CAUSE A MOSTLY WESTWARD TRACK FOR THE NEXT DAY OR SO
WITH A TURN TO THE WEST-SOUTHWEST THEREAFTER.  THE LATTER HAS OFTEN
BEEN NOTED AS TROPICAL CYCLONES INTERACT WITH THE VERY HIGH TERRAIN
OF THE SIERRA MADRE ORIENTAL MOUNTAINS OF MEXICO.  MOST OF THE
TRACK GUIDANCE MODELS ARE IN AGREEMENT ON THIS GENERAL SCENARIO AS
WELL.

GIVEN THE LARGE SIZE OF THE CIRCULATION OF ARLENE...ONE SHOULD NOT
FOCUS ON THE EXACT FORECAST TRACK...AS IMPACTS WILL LIKELY BE FELT
OVER A LARGE PORTION OF NORTHEASTERN MEXICO WELL AWAY FROM THE
CENTER.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  29/2100Z 21.1N  96.1W   45 KT  50 MPH
 12H  30/0600Z 21.1N  96.9W   55 KT  65 MPH
 24H  30/1800Z 21.0N  98.0W   50 KT  60 MPH...INLAND
 36H  01/0600Z 20.6N  99.5W   25 KT  30 MPH...INLAND
 48H  01/1800Z 20.0N 101.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  02/1800Z...DISSIPATED
 
$$
FORECASTER PASCH
 

WTNT41 KNHC 300240
TCDAT1
 
TROPICAL STORM ARLENE DISCUSSION NUMBER   6
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012011
1000 PM CDT WED JUN 29 2011
 
AN AIR FORCE HURRICANE HUNTER AIRCRAFT REPORTED PEAK FLIGHT-LEVEL
WINDS OF 64 KT ON ITS FIRST PASS THROUGH ARLENE WHICH EQUATES TO
ABOUT 50 KT SURFACE WINDS AND A MINIMUM PRESSURE OF 996 MB.
SEVERAL SFMR WIND MEASUREMENTS CLOSE TO 50 KT WERE ALSO RECORDED ON
THAT PASS AND THE SUBSEQUENT ONE AROUND 2300 UTC.  EARLIER
MICROWAVE PASSES REVEALED A PROMINENT BAND OVER THE SOUTHERN
SEMICIRCLE BUT A LACK OF ANY DISTINGUISHING CENTRAL FEATURES.  THE
LATTER MATCHES WHAT THE PLANE ALSO FOUND...A LARGE REGION OF LIGHT
AND VARIABLE WINDS NEAR THE CENTER.  ON THE BASIS OF THE PLANE
REPORTS AND 0000 UTC TAFB/SAB SATELLITE CLASSIFICATIONS OF
3.5/3.0...THE INITIAL INTENSITY IS HELD AT 50 KT. ALTHOUGH THE
WINDS ALOFT ARE GENERALLY FAVORABLE AND THE WATERS UNDERNEATH THE
CYCLONE ARE VERY WARM...THE CURRENT STORM STRUCTURE DOES NOT SEEM
SUITABLE FOR SIGNIFICANT INTENSIFICATION.  BESIDES...THE WINDOW OF
OPPORTUNITY FOR STRENGTHENING IS DECREASING NOW THAT LANDFALL SEEMS
IMMINENT. THE OFFICIAL NHC FORECAST REMAINS IN LINE WITH THE
STATISTICAL INTENSITY GUIDANCE AND INDICATES ARLENE REACHING A
PEAK INTENSITY NEAR HURRICANE STRENGTH IMMEDIATELY BEFORE LANDFALL.
 
THE SEQUENCE OF AIRCRAFT FIXES FROM THE MORNING AND LATE AFTERNOON
FLIGHTS YIELDED LITTLE OVERALL MOTION...BUT RECENT SATELLITE IMAGERY
SUGGESTS THAT ARLENE MAY HAVE BEGUN TO MOVE SLIGHTLY FASTER. A
STRONG MID-TROPOSPHERIC AREA OF HIGH PRESSURE BUILDING TO THE NORTH
AND NORTHWEST OF THE CYCLONE SHOULD INDUCE A GENERALLY WESTWARD
TRACK TO NEAR LANDFALL.  A TURN TOWARD THE WEST-SOUTHWEST IS
POSSIBLE AFTER THAT AS THE ORIENTATION OF THE RIDGE CHANGES AND AS
THE CYCLONE INTERACTS WITH LAND.  THE OFFICIAL NHC FORECAST IS VERY
SIMILAR TO BUT A BIT SLOWER THAN THE PREVIOUS TRACK DUE TO EARLIER
DECELERATION.
 
AIRCRAFT DATA INDICATE THAT TROPICAL-STORM-FORCE WINDS HAVE EXPANDED
SIGNIFICANTLY TO THE SOUTHWEST AND THE WIND RADII HAVE BEEN
MODIFIED ACCORDINGLY.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  30/0300Z 21.5N  96.1W   50 KT  60 MPH
 12H  30/1200Z 21.5N  97.0W   60 KT  70 MPH
 24H  01/0000Z 21.3N  98.2W   45 KT  50 MPH...INLAND
 36H  01/1200Z 20.7N  99.4W   25 KT  30 MPH...INLAND
 48H  02/0000Z 20.5N 100.5W   20 KT  25 MPH...POST-TROP/REMNT LOW
 72H  03/0000Z...DISSIPATED
 
$$
FORECASTER KIMBERLAIN/BROWN
 

WTNT41 KNHC 300848
TCDAT1
 
TROPICAL STORM ARLENE DISCUSSION NUMBER   7
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012011
400 AM CDT THU JUN 30 2011
 
SATELLITE IMAGES AND SURFACE DATA INDICATE THAT THE CENTER OF ARLENE
IS MAKING LANDFALL ON THE COAST OF MEXICO NEAR CABO ROJO. WHILE
ASCAT DATA SHOWED WINDS NO HIGHER THAN ABOUT 40 KT AROUND 0312
UTC...BANDING HAS INCREASED NOTABLY SINCE THAT TIME IN THE
NORTHEAST QUADRANT OF THE CYCLONE. SUBJECTIVE SATELLITE INTENSITY
ESTIMATES ARE BOTH 55 KT AND THE INITIAL WIND SPEED IS SET TO THAT
VALUE. THESE WINDS ARE LIKELY OCCURRING WELL NORTH OF THE CENTER IN
THE STRONG BANDING FEATURES. WEAKENING SHOULD BEGIN DURING THE NEXT
FEW HOURS AS THE CENTER MOVES INLAND. A RAPID DECAY IS LIKELY LATER
TODAY AS THE TROPICAL CYCLONE INTERACTS WITH THE MOUNTAINOUS
TERRAIN OF MEXICO.
 
ARLENE ACCELERATED AS IT APPROACHED THE COAST OVERNIGHT...AND IS
MOVING WESTWARD AT ABOUT 8 KT. MOST OF THE MODELS SUGGEST THAT THE
LOW-LEVEL CENTER WILL MOVE A LITTLE SLOWER AND DECOUPLE FROM THE
MID-LEVEL CIRCULATION AS THE FORMER IS BLOCKED BY THE SIERRA MADRE
ORIENTAL MOUNTAIN RANGE. BECAUSE OF THE FASTER INITIAL MOTION...
THE OFFICIAL FORECAST NOW SHOWS ARLENE DISSIPATED BY 36 HOURS.
 
WIND RADII HAVE BEEN MODIFIED BASED UPON THE EARLIER ASCAT PASS AND
DATA FROM NOAA BUOY 42055.
  
FORECAST POSITIONS AND MAX WINDS
 
INIT  30/0900Z 21.5N  97.3W   55 KT  65 MPH...
 12H  30/1800Z 21.4N  98.3W   40 KT  45 MPH...INLAND
 24H  01/0600Z 21.0N  99.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
 36H  01/1800Z...DISSIPATED
 
$$
FORECASTER BLAKE/FRANKLIN
 

WTNT41 KNHC 301442
TCDAT1
 
TROPICAL STORM ARLENE DISCUSSION NUMBER   8
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012011
1000 AM CDT THU JUN 30 2011
 
SATELLITE IMAGERY AND DATA FROM THE MEXICAN AUTOMATED STATION AT
ISLA LOBOS INDICATE THAT THE CENTER OF ARLENE HAS MADE LANDFALL
ALONG THE COAST OF EASTERN MEXICO.  THE STATION REPORTED A MINIMUM
PRESSURE OF 993 MB AS THE CENTER PASSED JUST TO THE NORTH...AND
BASED ON THIS AND A JUST-RECEIVED AMSU INTENSITY ESTIMATE THE
INITIAL INTENSITY REMAINS 55 KT.  SATELLITE DATA SUGGEST THE VORTEX
IS TILTED SOUTHWARD WITH HEIGHT...AS THE APPARENT CENTER IN
SATELLITE IMAGERY IS SOUTH OF THE CENTER LOCATION INDICATED BY THE
SURFACE OBSERVATIONS.
 
ARLENE CONTINUES TO MOVE IN FITS AND STARTS...WITH AN OVERALL MOTION
OF 270/6.  A MID-LEVEL RIDGE OVER NORTHERN MEXICO AND THE U. S.
SOUTHERN PLAINS SHOULD STEER THE CYCLONE GENERALLY WESTWARD TO
WEST-SOUTHWESTWARD UNTIL IT DISSIPATES OVER THE MOUNTAINS OF
CENTRAL MEXICO IN 24-36 HR.
 
ARLENE IS FORECAST TO WEAKEN OVER EASTERN MEXICO...WITH THE CYCLONE
DISSIPATING OVER THE MOUNTAINS OF CENTRAL MEXICO BY 36 HR.  SEVERAL
OF THE GLOBAL MODELS SHOW A LOW PRESSURE AREA FORMING ALONG THE
PACIFIC COAST OF MEXICO IN 24-48 HR...WHICH MOVES WESTWARD TO THE
SOUTH OF BAJA CALIFORNIA.  WHETHER THIS IS THE REMAINS OF ARLENE OR
A NEW SYSTEM IS SPECULATIVE AT THIS TIME.  EITHER WAY...SIGNIFICANT
DEVELOPMENT OF THIS SYSTEM APPEARS UNLIKELY DUE TO COLD SEA SURFACE
TEMPERATURES ALONG THE EXPECTED PATH.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  30/1500Z 21.6N  97.7W   55 KT  65 MPH
 12H  01/0000Z 21.4N  99.0W   35 KT  40 MPH...INLAND
 24H  01/1200Z 21.2N 100.4W   20 KT  25 MPH...POST-TROP/REMNT LOW
 36H  02/0000Z...DISSIPATED
 
$$
FORECASTER BEVEN
 

WTNT41 KNHC 302041
TCDAT1
 
TROPICAL STORM ARLENE DISCUSSION NUMBER   9
NWS NATIONAL HURRICANE CENTER MIAMI FL       AL012011
400 PM CDT THU JUN 30 2011

SSM/IS DATA BACK FROM THE TIME OF LANDFALL SHOWED A MID-LEVEL EYE
FEATURE ABOUT 35 N MI SOUTH-SOUTHWEST OF THE LOW-LEVEL CIRCULATION
CENTER.  THIS CONFIRMS THAT ARLENE HAD ISSUES WITH ITS VERTICAL
ALIGNMENT AS WELL AS HAVING AN ELONGATED LOW-LEVEL CIRCULATION. 
SINCE LANDFALL...THE LOW-LEVEL CIRCULATION HAS BECOME LESS DEFINED
IN BOTH SATELLITE IMAGERY AND SURFACE OBSERVATIONS FROM
MEXICO...AND THE CENTER HAS BECOME DIFFICULT TO LOCATE.  THE
INITIAL INTENSITY IS REDUCED TO 35 KT BASED ON ASCAT DATA BACK AT
15Z AND THE POSSIBILITY THAT TROPICAL-STORM FORCE WINDS ARE STILL
PRESENT OVER WATER EAST OF THE CENTER.

THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 255/6.  ARLENE SHOULD
CONTINUE TO MOVE GENERALLY WEST-SOUTHWESTWARD UNTIL THE
CIRCULATION DISSIPATES OVER THE MOUNTAINS OF MEXICO ON FRIDAY.
 
ARLENE IS FORECAST TO DISSIPATE OVER THE MOUNTAINS OF CENTRAL MEXICO
IN 24-36 HR...AND IT MAY NOT LAST THAT LONG.  SEVERAL GLOBAL MODELS
CONTINUE TO SHOW A LOW PRESSURE AREA FORMING ALONG THE PACIFIC
COAST OF MEXICO IN 24-48 HR...WHICH MOVES WESTWARD TO THE SOUTH OF
BAJA CALIFORNIA.  WHETHER THIS IS THE REMAINS OF ARLENE OR A NEW
SYSTEM REMAINS SPECULATIVE.  EITHER WAY... SIGNIFICANT DEVELOPMENT
OF THIS SYSTEM APPEARS UNLIKELY DUE TO COLD SEA SURFACE
TEMPERATURES ALONG THE EXPECTED PATH.
 
FORECAST POSITIONS AND MAX WINDS
 
INIT  30/2100Z 21.3N  98.3W   35 KT  40 MPH...INLAND
 12H  01/0600Z 21.1N  99.3W   30 KT  35 MPH...INLAND
 24H  01/1800Z 20.6N 100.4W   20 KT  25 MPH...POST-TROP/REMNT LOW
 36H  02/0600Z...DISSIPATED
 
$$
FORECASTER BEVEN
 

