|
Show Selection: |
| #44667 (Received by flhurricane at: 5:05 AM 08.Sep.2005) TCDAT1 TROPICAL STORM OPHELIA DISCUSSION NUMBER 8 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL 5 AM EDT THU SEP 08 2005 AIRCRAFT RECON FLIGHT-LEVEL WINDS OF 61 KT AND MELBOURNE WSR-88D DOPPLER RADAR VELOCITIES OF 60-64 KT BETWEEN 6000-7000 FT SUPPORT INCREASING THE INITIAL INTENSITY TO 50 KT. HOWEVER...RECON DATA JUST IN INDICATES SURFACE WINDS OF 56 KT AND A CENTRAL PRESSURE OF 987 MB. IF THIS NEW DEVELOPMENT PERSISTS...THEN A SPECIAL ADVISORY WILL BE ISSUED TO INCREASE THE INTENSITY AND LOWER THE CENTRAL PRESSURE. THE INITIAL MOTION REMAINS STATIONARY. OPHELIA IS EXPECTED TO REMAIN IN WEAK STEERING FLOW FOR THE NEXT 3 TO PERHAPS 5 DAYS AS THE LOW-LEVEL RIDGE TO THE NORTH REMAINS INTACT...WHILE THE MID-LEVEL FLOW BECOMES MORE NORTHWEST AND NORTHERLY...AND THE UPPER-LEVEL FLOW REMAINS SOUTHERLY. THE NHC MODEL GUIDANCE IS IN MUCH BETTER AGREEMENT ON A SOW NORTHWARD MOTION THROUGH 48 HOURS WITH A GENERAL EASTWARD MOTION AFTER THAT. THE MAIN QUESTION IS HOW FAR EAST WILL OPHELIA GO BEFORE IT LOOPS BACK TO THE WEST. THE GFDL IS THE FARTHEST WEST MODEL AND MOVES THE CYCLONE INTO SOUTHEAST GEORGIA IN 96 HOURS...WHEREAS THE GFS IS MUCH FASTER AND TAKES OPHELIA MORE THAN 500 NMI EAST OF ITS CURRENT POSITION. THE REST OF THE MODELS ARE SOMEWHERE IN BETWEEN. THE OFFICIAL TRACK REMAINS SLOW AND SIMILAR TO THE PREVIOUS FEW FORECASTS AND IS TO THE LEFT OF AND SLOWER THAN THE NHC MODEL CONSENSUS...WHICH I FEEL HAS A FAST BIAS DUE TO THE MUCH FASTER GFS MODEL. THE GFS PERFORMED SIMILARLY DURING HURRICANE JEANNE LAST YEAR AND HAD SOME VERY LARGE TRACK ERRORS. SLOW BUT STEADY INTENSIFICATION IS FORECAST SINCE OPHELIA IS EXPECTED TO REMAIN OVER 29C AND WARMER SSTS AND UNDER LIGHT OT MODERATE SOUTHERLY UPPER-LEVEL SHEAR THROUGH 96 HOURS. AFTER THAT ...MORE STRENGTHENING THAN WHAT IS CURRENTLY FORECAST COULD OCCUR SINCE THE SHEAR IS EXPECTED TO DROP BELOW 10 KT. HOWEVER...THE EXPECTED CLOSE PROXIMITY OF VERY DRY MID-LEVEL AIR PRECLUDES INCREASING THE INTENSITY IN THE LATTER PERIODS AT THIS TIME. ALL INTERESTS IN NORTH FLORIDA AND SOUTHEASTERN GEORGIA SHOULD MONITOR THE PROGRESS OF THIS DEVELOPING CYCLONE. SHOULD OPHELIA STRENGTHEN FASTER AND MOVE CLOSER TO THE COAST THAN CURRENTLY FORECAST...A HURRICANE WATCH MAY BE NECESSARY SOMETIME ON THURSDAY. FORECASTER STEWART FORECAST POSITIONS AND MAX WINDS INITIAL 08/0900Z 28.7N 79.5W 50 KT 12HR VT 08/1800Z 29.0N 79.6W 55 KT 24HR VT 09/0600Z 29.4N 79.6W 55 KT 36HR VT 09/1800Z 29.9N 79.4W 60 KT 48HR VT 10/0600Z 30.0N 79.1W 65 KT 72HR VT 11/0600Z 30.2N 78.5W 65 KT 96HR VT 12/0600Z 30.3N 78.0W 70 KT 120HR VT 13/0600Z 30.0N 78.0W 70 KT |
