000
WTNT41 KNHC 312031
TCDAT1
HURRICANE TOMAS DISCUSSION NUMBER  11
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL212010
500 PM AST SUN OCT 31 2010
 
DATA FROM AN AIR FORCE RESERVE RECONNAISSANCE AIRCRAFT INDICATE THAT
TOMAS HAS WEAKENED A LITTLE MORE.  THE AIRCRAFT REPORTED A MAXIMUM
850 MB FLIGHT-LEVEL WIND OF 74 KT...AN SFMR SURFACE WIND OF 64
KT...AND A MINIMUM PRESSURE OF 994 MB.  THESE DATA SUPPORT
MAINTAINING TOMAS AS A HURRICANE WITH AN INITIAL WIND SPEED OF 65
KT.
 
THE INITIAL MOTION IS SLIGHTLY TO THE LEFT AND A LITTLE FASTER THAN
BEFORE...280/10.  TOMAS IS FORECAST TO CONTINUE MOVING WESTWARD FOR
THE NEXT COUPLE OF DAYS AS IT REMAINS SOUTH OF A MID-LEVEL RIDGE.
BEYOND THAT TIME...THE CYCLONE IS EXPECTED TO SLOW DOWN AND
GRADUALLY TURN TOWARD THE NORTH AS THE STEERING CURRENTS WEAKEN DUE
TO A LARGE MID- TO UPPER-LEVEL TROUGH MOVING ACROSS THE GULF OF
MEXICO.  ALTHOUGH THE TRACK MODEL GUIDANCE IS IN FAIR AGREEMENT IN
THE EVOLUTION OF THE LARGE-SCALE PATTERN...THERE ARE CONSIDERABLE
DIFFERENCES AS TO WHERE AND WHEN THE NORTHWARD TURN OCCURS.  THE
OFFICIAL FORECAST IS SIMILAR TO THE PREVIOUS ONE FOR THE NEXT 3 TO
4 DAYS...AND THEN LIES A LITTLE TO THE RIGHT OF THE LAST TRACK TO
COME INTO BETTER AGREEMENT WITH THE LATEST GUIDANCE.  THIS TRACK
FORECAST IS CLOSE TO A CONSENSUS OF THE GFS...GFDL...ECMWF...AND
UKMET MODELS. IT SHOULD BE NOTED THAT CONFIDENCE IN THE LONG-TERM
FORECAST POINTS ARE OF LOWER CONFIDENCE THAN NORMAL.
 
SOME ADDITIONAL WEAKENING SEEMS LIKELY DURING THE NEXT DAY OR TWO AS
SOUTHWESTERLY SHEAR OF 20-25 KT AND SOME MID-LEVEL DRY AIR CONTINUE
TO IMPACT THE CYCLONE.  THE OFFICIAL FORECAST FOLLOWS THE TREND IN
THE GUIDANCE AND IS ONCE AGAIN ADJUSTED DOWNWARD...BRINGING TOMAS
BELOW HURRICANE STRENGTH WITHIN THE NEXT 12 HOURS.  BEYOND A COUPLE
OF DAYS...THE SHEAR IS EXPECTED TO LESSEN WHILE TOMAS REMAINS OVER
FAVORABLE OCEANIC CONDITIONS.  ALL OF THE INTENSITY MODELS RESPOND
AND SHOW THE SYSTEM INTENSIFYING IN THE 3 TO 5 DAY RANGE...AND THE
OFFICIAL FORECAST FOLLOWS SUIT AND IS AT THE HIGH END OF THE
GUIDANCE THROUGHOUT THE FORECAST PERIOD.
 

FORECAST POSITIONS AND MAX WINDS
 
INITIAL      31/2100Z 14.4N  64.9W    65 KT
 12HR VT     01/0600Z 14.7N  66.4W    60 KT
 24HR VT     01/1800Z 15.0N  68.3W    55 KT
 36HR VT     02/0600Z 15.0N  69.9W    55 KT
 48HR VT     02/1800Z 15.0N  71.3W    60 KT
 72HR VT     03/1800Z 15.3N  72.5W    65 KT
 96HR VT     04/1800Z 16.0N  73.0W    80 KT
120HR VT     05/1800Z 18.5N  72.5W    90 KT...INLAND
 
$$
FORECASTER CANGIALOSI/BROWN