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| #539987 (Received by flhurricane at: 4:44 AM 04.Sep.2012) TCDAT3 TROPICAL DEPRESSION THIRTEEN DISCUSSION NUMBER 3 NWS NATIONAL HURRICANE CENTER MIAMI FL AL132012 500 AM EDT TUE SEP 04 2012 SMALL BANDS OF DEEP CONVECTION CONTINUE TO WRAP AROUND THE EASTERN SIDE OF THE DEPRESSION AND NIGHT VISIBLE IMAGES INDICATE THE CENTER IS JUST WEST OF THE SOUTHERNMOST BAND. INTENSITY ESTIMATES WERE 35 KT AND 30 KT FROM TAFB/SAB RESPECTIVELY...AND GIVEN THE LACK OF ANY SIGNIFICANT CHANGE IN SATELLITE IMAGERY DURING THE PAST FEW HOURS...THE INITIAL WINDS ARE KEPT AT 30 KT. THE FUTURE STRENGTH OF THE DEPRESSION IS NOT AN EASY PREDICTION AS IT IS VERY CLOSE TO SOME STRONG NORTHWESTERLY SHEAR. HOWEVER...THE BULK OF THE MODEL GUIDANCE IS NOW INDICATING THAT THIS SHEAR WILL STAY AWAY FROM THE CYCLONE...WITH LITTLE CHANGE IN THE ENVIRONMENT PROBABLE FOR THE NEXT COUPLE OF DAYS WHILE THE CYCLONE REMAINS OVER WARM WATERS. AN UPPER-LEVEL TROUGH IS FORECAST BY MANY GLOBAL MODELS TO CUT OFF TO THE SOUTHWEST OF THE DEPRESSION IN A FEW DAYS...WHICH COULD CREATE A FAVORABLE WIND PATTERN FOR INTENSIFICATION. WITH THE CHANGE IN THE FORECAST LARGE-SCALE ENVIRONMENT...IT DOES NOT SEEM AS LIKELY THAT THE DEPRESSION WILL BECOME A REMNANT LOW ANYTIME SOON...AND THE NEW FORECAST NO LONGER SHOWS THAT TRANSITION. THE LATEST PREDICTION IS CLOSE TO THE MODEL CONSENSUS DURING THE FORECAST PERIOD...BUT IS MUCH LOWER THAN THE SHIPS/LGEM GUIDANCE. IF THE DEPRESSION WERE TO TRACK FARTHER TO THE LEFT THAN ANTICIPATED IN THE NEAR TERM...THEN MORE WEAKENING THAN SHOWN BELOW IS LIKELY...WHICH COULD ALSO CAUSE THE SYSTEM TO DEGENERATE INTO A REMNANT LOW. BEST ESTIMATE OF INITIAL MOTION IS 310/5. THE CYCLONE SHOULD TURN TOWARD THE NORTH-NORTHWEST AND NORTH OVER THE NEXT 24H OR SO AS IT MOVES AROUND A WEAK SUBTROPICAL RIDGE OVER THE EASTERN ATLANTIC OCEAN. STEERING CURRENTS ARE QUITE LIGHT AFTER THAT TIME...WITH THE MIDDLE- TO UPPER-LEVEL LOW DROPPING TO THE SOUTH AND WEST OF THE DEPRESSION IN A FEW DAYS THAT COULD CAUSE A SLOW NORTHWEST OR NORTHWARD MOTION IN THE 3 TO 5 DAY PERIOD. THE LATEST NHC FORECAST IS VERY CLOSE TO THE PREVIOUS ONE...BUT IS ADJUSTED A BIT TO THE NORTH AND WEST AT LONG RANGE...ON THE LEFT SIDE OF THE TVCA MODEL. FORECAST POSITIONS AND MAX WINDS INIT 04/0900Z 26.5N 43.3W 30 KT 35 MPH 12H 04/1800Z 26.9N 43.9W 30 KT 35 MPH 24H 05/0600Z 27.6N 44.3W 30 KT 35 MPH 36H 05/1800Z 28.3N 44.4W 30 KT 35 MPH 48H 06/0600Z 28.8N 44.0W 30 KT 35 MPH 72H 07/0600Z 30.0N 43.5W 30 KT 35 MPH 96H 08/0600Z 31.5N 44.5W 35 KT 40 MPH 120H 09/0600Z 33.0N 44.5W 35 KT 40 MPH $$ FORECASTER BLAKE |
