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Tropical Storm TOMAS (Text)

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TROPICAL STORM TOMAS DISCUSSION NUMBER  25
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL212010
500 AM EDT THU NOV 04 2010
 
SATELLITE PICTURES SUGGEST THAT THE CLOUD PATTERN OF TOMAS HAS NOT
CHANGED SIGNIFICANTLY DURING THE LAST SEVERAL HOURS.  HOWEVER...
DATA FROM AN AIR FORCE RESERVE HURRICANE HUNTER AIRCRAFT INDICATE
THAT THE PRESSURE HAS FALLEN TO 997 MB WITH MAXIMUM SURFACE WINDS
OF 41 KT.  DESPITE THE AIRCRAFT DATA WHICH ARE INDICATIVE OF SLIGHT
STRENGTHENING...THE VORTEX HAS BEEN TILTED IN THE VERTICAL BASED
UPON  COMPARISON OF EARLIER NOAA AND AIR FORCE AIRCRAFT DATA.
GIVEN THE SIGNIFICANTLY LOWER CENTRAL PRESSURE FROM THE AIRCRAFT...
THE INITIAL INTENSITY IS INCREASED TO 45 KT FOR THIS ADVISORY.
 
THE CURRENT MOTION ESTIMATE REMAINS 330/06.  THE FORECAST PHILOSOPHY
REGARDING THE TRACK OF TOMAS IS UNCHANGED.  TOMAS SHOULD BE STEERED
NORTH-NORTHWESTWARD TO NORTHWARD AROUND A LOW- TO MID-LEVEL RIDGE
LOCATED OVER THE WEST CENTRAL ATLANTIC TODAY.  AFTER THAT...TOMAS
SHOULD BEGIN TO ENCOUNTER AN INCREASING SOUTHWESTERLY FLOW
ASSOCIATED WITH AN ANOMALOUSLY DEEP MID- TO UPPER-LEVEL TROUGH
MOVING ACROSS EASTERN NORTH AMERICA AND TURN NORTHEASTWARD WHILE
ACCELERATING.  EVEN THOUGH THE SYNOPTIC REASONING HAS NOT CHANGED
FROM THE PREVIOUS PACKAGE...THE OFFICIAL FORECAST TRACK IS SHIFTED
TO THE LEFT ON ACCOUNT OF THE MOST RECENT AIRCRAFT CENTER FIXES.
 
ALTHOUGH LARGE-SCALE FACTORS OF MODERATELY LOW SHEAR AND WARM WATERS
ARE FAVORABLE FOR FURTHER INTENSIFICATION OF TOMAS...THE VERTICAL
TILT OF THE VORTEX AND THE BROAD NATURE OF THE CIRCULATION MAY
ARGUE AGAINST A RAPID INCREASE IN STRENGTH.  INTERESTINGLY...THE
SHIPS RAPID INTENSIFICATION INDEX THAT HAD BEEN SHOWING THE
POTENTIAL FOR A 30-KT INCREASE WITHIN THE NEXT 24 HOURS IS NOT AS
HIGH AS IT WAS BEFORE.  THE NEW NHC FORECAST IS SIMILAR TO THE
PREVIOUS ONE AND ASSUMES THAT THE LARGE-SCALE ENVIRONMENT SHOULD BE
CONDUCIVE ENOUGH TO ALLOW FOR STENGTHENING DURING THE NEXT 24-36
HOURS.  BEYOND 36 HOURS...STRONG AND INCREASING SOUTHWESTERLY SHEAR
OVER THE WESTERN ATLANTIC IS FORECAST TO CAUSE WEAKENING...PERHAPS
AT A MORE RAPID PACE THAN INDICATED IN THE CURRENT FORECAST.  THE
NEW NHC FORECAST IS REDUCED FROM THE PREVIOUS ONE AT LATER FORECAST
TIMES GIVEN THE STRONG FORECAST SHEAR.
 
REGARDLESS OF THE EXACT TRACK AND INTENSITY OF TOMAS...THE MOST
SIGNIFICANT THREAT FROM THIS TROPICAL CYCLONE IS HEAVY RAINFALL...
WHICH COULD PRODUCE FLASH FLOODING AND LIFE-THREATENING MUD SLIDES
OVER HAITI AND THE DOMINICAN REPUBLIC DURING THE NEXT COUPLE OF
DAYS.
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      04/0900Z 15.8N  76.1W    45 KT
 12HR VT     04/1800Z 17.0N  76.0W    55 KT
 24HR VT     05/0600Z 18.8N  75.0W    65 KT
 36HR VT     05/1800Z 21.0N  73.4W    65 KT
 48HR VT     06/0600Z 23.5N  71.5W    55 KT
 72HR VT     07/0600Z 26.0N  69.5W    45 KT
 96HR VT     08/0600Z 28.0N  67.0W    35 KT
120HR VT     09/0600Z 28.0N  65.0W    25 KT
 
$$
FORECASTER KIMBERLAIN/PASCH
 
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