|
Show Selection: |
| #37597 (Received by flhurricane at: 4:52 AM 05.Aug.2005) TCDAT3 TROPICAL STORM HARVEY DISCUSSION NUMBER 12 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT FRI AUG 05 2005 CONVENTIONAL AND MICROWAVE SATELLITE IMAGERY INDICATE HARVEY IS EXPERIENCING SIGNIFICANT WEST-SOUTHWESTERLY UPPER-LEVEL SHEAR... WHICH HAS CAUSED THE LOW-LEVEL CIRCULATION TO LAG BEHIND TO THE SOUTHWEST OF THE MID- AND UPPER-LEVEL CIRCULATIONS. THE OVERALL CONVECTIVE PATTERN HAS ALSO BECOME LESS DISTINCT...ALTHOUGH A BURST OF DEEP CONVECTION HAS REDEVELOPED OVER AND JUST NORTHEAST OF THE SURFACE CENTER DURING THE PAST COUPLE OF HOURS. THE INTENSITY IS BEING MAINTAINED AT 55 KT BASED ON DVORAK T-NUMBERS OF T3.5/55 KT FROM BOTH TAFB AND SAB...AND A COUPLE OF 55 KT UNFLAGGED WIND VECTORS NOTED IN A 04/2228Z QUIKSCAT OVERPASS. THE INITIAL MOTION ESTIMATE IS 070/08. THE INITIAL POSITION WAS ADJUSTED ABOUT 30 NMI SOUTH OF THE PREVIOUS POSITIONS AND FORECAST TRACK. OTHER THAN THAT...THE FORECAST TRACK AND REASONING REMAINS UNCHANGED FROM THE PAST FEW ADVISORIES. A SHORTWAVE TROUGH TO THE NORTH OF HARVEY THAT HAD BEEN MOVING THE CYCLONE ALONG AT A DECENT CLIP HAS NOW LIFTED OUT TO THE NORTHEAST AS NOTED IN WATER VAPOR IMAGERY. THIS HAS RESULTED IN A WEAKENING OF THE STEERING FLOW. HOWEVER...ANOTHER UPSTREAM SHORTWAVE CURRENTLY MOVING OVER SOUTHEASTERN CANADA IS EXPECTED TO DIG SOUTHWARD AND SLOWLY LIFT HARVEY NORTHEASTWARD BY 36 HOURS...WITH GRADUAL ACCELERATION OVER COOLER WATER EXPECTED AFTER THAT. THE OFFICIAL FORECAST TRACK IS SIMILAR TO THE PREVIOUS ADVISORY...AND IS A LITTLE SLOWER AND TO THE RIGHT OF THE NHC MODEL CONSENSUS. THE VERTICAL SHEAR IS FORECAST TO WEAKEN TO LESS THAN 10 KT BY 24 HOURS...SO LITTLE CHANGE IN INTENSITY IS EXPECTED BEFORE THEN. AFTERWARDS...HOWEVER...THE VERTICAL SHEAR WILL GRADUALLY INCREASE TO 30 KT OR MORE BY 96 HOURS AS HARVEY ALSO MOVES OVER SUB-26C SSTS. THIS SHOULD BRING ABOUT STEADY WEAKENING AND POSSIBLE TRANSITION TO AN EXTRATROPICAL LOW BY 96 HOURS. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 05/0900Z 32.5N 59.0W 55 KT 12HR VT 05/1800Z 32.9N 57.9W 55 KT 24HR VT 06/0600Z 33.5N 57.0W 55 KT 36HR VT 06/1800Z 34.6N 56.1W 50 KT 48HR VT 07/0600Z 36.0N 55.0W 50 KT 72HR VT 08/0600Z 39.1N 50.5W 45 KT 96HR VT 09/0600Z 42.5N 44.0W 40 KT...BECOMING EXTRATROPICAL 120HR VT 10/0600Z 47.0N 34.0W 30 KT...EXTRATROPICAL |
