ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM 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 NNNN
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Page last modified: Thursday, 31-Dec-2009 12:09:03 UTC