Show Selection: |
#287560 (Received by flhurricane at: 4:37 AM 12.Aug.2009) TCDAT2 TROPICAL DEPRESSION TWO DISCUSSION NUMBER 5 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL022009 500 AM AST WED AUG 12 2009 SATELLITE IMAGES INDICATE THAT A PERSISTENT CLUSTER OF THUNDERSTORMS REMAINS IN THE WESTERN SEMICIRCLE OF THE DEPRESSION...ALTHOUGH RECENTLY THIS CLUSTER HAS TAKEN ON A SOMEWHAT ELONGATED APPEARANCE. MICROWAVE AND SHORTWAVE INFRARED DATA SUGGEST THE CENTER REMAINS ON THE EASTERN SIDE OF THE CONVECTION AND NOT WELL-EMBEDDED WITHIN THE MAIN CONVECTIVE CLUSTER. DVORAK ESTIMATES SUGGEST THE MAXIMUM WINDS ARE NEAR 30 KT...AND THE INITIAL INTENSITY WILL BE HELD AT THAT VALUE. THERE IS CONSIDERABLE UNCERTAINTY WITH THE INITIAL POSITION...AND THE BEST GUESS OF INITIAL MOTION IS 270/10. GLOBAL MODELS SUGGEST A GENERAL WESTERLY COURSE IS LIKELY FOR THE NEXT COUPLE OF DAYS AS RIDGING BUILDS TO THE NORTH OF THE DEPRESSION. THEREAFTER...A WEAKNESS IN THE SUBTROPICAL HIGH OVER THE CENTRAL ATLANTIC OCEAN COULD CAUSE THE TROPICAL CYCLONE TO GAIN SOME LATITUDE. ALTHOUGH THE HWRF/BAMD MODELS SHOW A SHARP NORTHWESTWARD MOTION IN THE LATTER HALF OF THE FORECAST PERIOD...MOST OF THE MODEL GUIDANCE SUGGEST ONLY A GRADUAL BEND TO A WEST-NORTHWEST TRACK WITH AN INCREASE IN FORWARD SPEED DUE TO A HIGH BUILDING OVER THE WESTERN ATLANTIC. THE OFFICIAL FORECAST IS ADJUSTED SLIGHTLY SOUTHWARD IN THE FIRST FEW DAYS...BUT ENDS UP VERY CLOSE TO THE PREVIOUS FORECAST BY THE END OF THE PERIOD. LIGHT TO MODERATE SOUTHEASTERLY SHEAR IS EXPECTED FOR THE NEXT SEVERAL DAYS WHILE THE SYSTEM TRAVERSES MARGINALLY WARM WATERS. IN GENERAL...THIS ENVIRONMENT WOULD SUPPORT SOME STRENGTHENING... THOUGH THE PRESENCE OF SOME DRIER/STABLE AIR JUST TO THE NORTH OF THE DEPRESSION MAY PLAY AN INHIBITING ROLE. THE STATISTICAL MODELS SUGGEST THAT THE DEPRESSION COULD BE CLOSE TO HURRICANE STRENGTH IN A FEW DAYS...WHILE THE DYNAMICAL GUIDANCE SHOWS ONLY A LOW-END TROPICAL STORM. THE NHC INTENSITY FORECAST WILL BASICALLY SPLIT THE DIFFERENCE BETWEEN THOSE OUTCOMES AND REMAINS CLOSE TO THE PREVIOUS ONE. IN THE LONGER-TERM...MOST OF THE GLOBAL MODELS INCREASE THE VERTICAL SHEAR...WHICH SHOULD CAUSE A WEAKENING TREND WHILE THE SYSTEM IS OVER THE CENTRAL ATLANTIC. FORECAST POSITIONS AND MAX WINDS INITIAL 12/0900Z 14.6N 32.4W 30 KT 12HR VT 12/1800Z 14.6N 34.0W 35 KT 24HR VT 13/0600Z 14.6N 36.4W 35 KT 36HR VT 13/1800Z 14.6N 38.9W 40 KT 48HR VT 14/0600Z 15.0N 41.4W 45 KT 72HR VT 15/0600Z 16.5N 46.5W 50 KT 96HR VT 16/0600Z 19.0N 52.5W 45 KT 120HR VT 17/0600Z 22.5N 58.5W 40 KT $$ FORECASTER BLAKE |