Tropical Storm ANA

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TROPICAL STORM ANA DISCUSSION NUMBER  16
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL   AL022009
1100 PM AST SAT AUG 15 2009
 
THE CONVECTION NEAR THE CENTER OF ANA HAS BEEN PULSATING AND AFTER
AN INCREASE FOR A FEW HOURS...THE LOW LEVEL CENTER HAS BECOME
EXPOSED AGAIN. THIS MEANS ANNA IS NOT STRENGTHENING AND THE INITIAL
INTENSITY IS KEPT AT 35 KNOTS. A NOAA JET FLEW AGAIN TONIGHT AND ONE
OF THE DROPS NEAR THE CENTER MEASURED A SURFACE PRESSURE OF 1004 MB
WHICH WAS USED FOR THIS ADVISORY. THE SHEAR IS NOT VERY STRONG AS
DIAGNOSED BY THE SHIPS MODELS BUT THE LOW-LEVEL CENTER OF ANA IS
SIMPLY MOVING TOO FAST. THIS RAPID MOTION IS PROBABLY NOT TOO
CONDUCIVE FOR INTENSIFICATION.  IN FACT...THE ONLY DYNAMICAL MODELS
THAT KEEP ANA ARE THE UK AND THE NOGAPS.  THE REST OF THEM WEAKEN
ANA TO A TROPICAL WAVE. I AM TEMPTED TO SHOW WEAKENING BUT FOR
NOW...I AM GOING TO FOLLOW THE PREVIOUS FORECAST AND SHIPS MODEL
GUIDANCE. THE OFFICIAL FORECAST SHOWS SLOW STRENGTHENING THROUGH 48
HOURS FOLLOWED BY WEAKENING AS THE CYCLONE INTERACTS WITH
HISPANIOLA AND CUBA.

THE INITIAL MOTION IS 270/15. ANA IS EMBEDDED WITHIN STRONG AND
PERSISTENT TRADE WINDS AND ONLY A SMALL TURN TO THE WEST-NORTHWEST
WITH AN INCREASE IN FORWARD SPEED IS ANTICIPATED. THE OFFICIAL
FORECAST IS A LITTLE BIT SLOWER THAN MOST OF THE GUIDANCE BUT IS
WELL INSIDE THE ENVELOPE THROUGH 48 HOURS. THEREAFTER...SOME MODELS
KEEP A WEAKER ANA SOUTH OF CUBA AND OTHERS BRING THE CYCLONE OVER
CUBA AND INTO THE GULF OF MEXICO.  THE OFFICIAL TRACK FORECAST IS
VERY SIMILAR TO THE PREVIOUS ONE AND FOLLOWS THE NORTHERNMOST GROUP
OF MODELS. 
 
 
FORECAST POSITIONS AND MAX WINDS
 
INITIAL      16/0300Z 14.4N  51.5W    35 KT
 12HR VT     16/1200Z 14.7N  54.1W    35 KT
 24HR VT     17/0000Z 15.5N  57.5W    40 KT
 36HR VT     17/1200Z 16.5N  61.2W    45 KT
 48HR VT     18/0000Z 17.5N  65.0W    50 KT
 72HR VT     19/0000Z 19.5N  73.0W    30 KT...INLAND
 96HR VT     20/0000Z 22.5N  78.9W    35 KT...OVER WATER
120HR VT     21/0000Z 25.0N  83.6W    40 KT
 
$$
FORECASTER AVILA
 
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