|
Show Selection: |
| #530963 (Received by flhurricane at: 4:47 PM 01.Aug.2012) TCDAT5 TROPICAL DEPRESSION FIVE DISCUSSION NUMBER 1 NWS NATIONAL HURRICANE CENTER MIAMI FL AL052012 500 PM AST WED AUG 01 2012 DURING THE DAY...VISIBLE SATELLITE IMAGES SHOWED THAT THE LOW-LEVEL CIRCULATION OF THE LOW PRESSURE SYSTEM TO THE EAST OF THE WINDWARD ISLANDS HAS BECOME BETTER DEFINED. DEEP CONVECTION HAS PULSED A BIT...AND IS SOMEWHAT LACKING OVER THE NORTHERN PART OF THE CIRCULATION. HOWEVER THE SYSTEM HAS NOW ACQUIRED SUFFICIENT ORGANIZATION TO BE CLASSIFIED AS A TROPICAL DEPRESSION. THE INITIAL WIND SPEED IS SET AT 30 KT IN ACCORDANCE WITH DVORAK ESTIMATES FROM TAFB AND SAB. FORECASTING INTENSITY CHANGE IS ALWAYS A CHALLENGE...AND IS PARTICULARLY TRUE IN THIS CASE. MODERATE VERTICAL SHEAR...ASSOCIATED WITH A LARGE UPPER-LEVEL LOW TO THE NORTH OF THE DEPRESSION...IS LIKELY TO AFFECT THE SYSTEM FOR THE NEXT COUPLE OF DAYS. THUS ONLY SLOW STRENGTHENING IS ANTICIPATED DURING THE FIRST HALF OF THE FORECAST PERIOD. LATER ON...THE INTENSITY FORECAST UNCERTAINTY INCREASES. OUR BEST TWO GLOBAL MODELS ARE AT ODDS AS TO HOW THE SYSTEM WILL EVOLVE AS IT MOVES OVER THE CARIBBEAN. THE GFS FORECASTS THE UPPER-LEVEL ENVIRONMENT TO BECOME QUITE CONDUCIVE FOR STRENGTHENING BY THE END OF THE FORECAST PERIOD...WHEREAS THE ECMWF MODEL SHOWS THE SYSTEM DEGENERATING INTO A TROPICAL WAVE. THE OFFICIAL FORECAST LEANS TOWARD TO THE GFS...BUT TIME WILL TELL. THE INITIAL MOTION IS A SOMEWHAT UNCERTAIN 285/16. GLOBAL MODELS DEPICT A STRONG MID-TROPOSPHERIC ANTICYCLONE TO THE NORTH OF THE TROPICAL CYCLONE FOR THE NEXT SEVERAL DAYS. THIS STEERING PATTERN SHOULD CAUSE A WEST-NORTHWESTWARD TO WESTWARD MOTION AT ABOUT THE SAME SPEED THROUGH MUCH OF THE FORECAST PERIOD. A WEAKNESS OVER THE GULF OF MEXICO COULD CAUSE SOME SLOWING AND BIT OF A NORTHWESTWARD TURN LATE IN THE PERIOD. THE COMPUTER MODELS ARE IN GOOD AGREEMENT...AND THE NHC TRACK FORECAST IS NOT FAR FROM THE MODEL CONSENSUS. FORECAST POSITIONS AND MAX WINDS INIT 01/2100Z 12.2N 49.0W 30 KT 35 MPH 12H 02/0600Z 12.7N 51.3W 40 KT 45 MPH 24H 02/1800Z 13.3N 54.5W 45 KT 50 MPH 36H 03/0600Z 13.8N 57.7W 50 KT 60 MPH 48H 03/1800Z 14.4N 60.9W 55 KT 65 MPH 72H 04/1800Z 15.5N 67.0W 55 KT 65 MPH 96H 05/1800Z 16.5N 73.0W 60 KT 70 MPH 120H 06/1800Z 17.5N 78.0W 65 KT 75 MPH $$ FORECASTER PASCH/BLAKE |
