ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM TROPICAL STORM ANA DISCUSSION NUMBER 18 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009 1100 AM AST SUN AUG 16 2009 ANA CONTINUES TO RACE WESTWARD...WITH LIMITED DEEP CONVECTION OVER THE LOW-LEVEL CENTER. A 0950 UTC QUIKSCAT PASS SHOWED SOME BELIEVABLE 30 KT WINDS...AND ASSUMING WINDS ARE HIGHER IN THE CONVECTION NEAR THE CENTER THE INTENSITY IS HELD GENEROUSLY AT 35 KT FOR THIS PACKAGE. AIRCRAFT RECONNAISSANCE WILL BE INVESTIGATING THE CYCLONE EARLY THIS AFTERNOON AND SHOULD HELP DETERMINE IF ANA IS STILL A TROPICAL STORM. THE ENVIRONMENT NEAR AND AHEAD OF ANA IS RATHER DRY AND DOMINATED BY SUBSIDENCE...AS INDICATED BY WATER VAPOR IMAGERY AND RADIOSONDE DATA FROM THE LESSER ANTILLES. THE GFDL...SHIPS...AND LGEM CONTINUE TO SUGGEST THAT ANA WILL INTENSIFY SOMEWHAT OVER THE NEXT COUPLE OF DAYS. HOWEVER...GIVEN THE NEGATIVE FACTORS DISCUSSED ABOVE...ONLY SLIGHT INTENSIFICATION IS SHOWN THROUGH 48 HOURS. BEYOND THAT TIME...THE INTENSITY OF ANA WILL BE DICTATED PRIMARILY BY ITS INTERACTION WITH HISPANIOLA AND CUBA...AND THE INTENSITY FORECAST ACCOUNTS FOR THIS WITH WEAKENING. THE TRACK FORECAST IS QUITE SIMILAR TO THE PREVIOUS PACKAGE... SHOWING A QUICK WESTWARD TO WEST-NORTHWESTWARD MOTION THROUGH THE FIRST 3 OR 4 DAYS OF THE FORECAST PERIOD. BEYOND THAT TIME THERE IS A SPLIT IN THE TRACK GUIDANCE...WITH THE ECMWF AND HWRF SHOWING A TURN TOWARD THE NORTHWEST...WHILE THE UKMET AND NOGAPS SHOW A CONTINUED WEST-NORTHWEST HEADING. THE OFFICIAL FORECAST IS NUDGED TOWARD THE MULTI-MODEL CONSENSUS AT DAY 5 AND SHOWS A DECREASE IN FORWARD SPEED. GIVEN THE UNCERTAINTY IN THE INITIAL INTENSITY OF ANA...TROPICAL STORM WATCHES CONTINUE FOR MOST OF THE NORTHERN LEEWARD ISLANDS... THE VIRGIN ISLANDS...AND PUERTO RICO. IF AIRCRAFT RECONNAISSANCE FINDS ANA IS A TROPICAL STORM...WARNINGS WILL LIKELY BE REQUIRED LATER TODAY. FORECAST POSITIONS AND MAX WINDS INITIAL 16/1500Z 14.8N 55.8W 35 KT 12HR VT 17/0000Z 15.2N 58.7W 35 KT 24HR VT 17/1200Z 16.1N 62.7W 40 KT 36HR VT 18/0000Z 17.1N 66.7W 40 KT 48HR VT 18/1200Z 18.3N 70.7W 45 KT 72HR VT 19/1200Z 21.0N 77.5W 30 KT...INLAND 96HR VT 20/1200Z 23.5N 83.0W 30 KT 120HR VT 21/1200Z 25.5N 85.5W 30 KT $$ FORECASTER BRENNAN/ROBERTS NNNN
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Page last modified: Thursday, 31-Dec-2009 12:09:03 UTC