WTNT41 KNHC 080904
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
$$
Wonderful discussion by Stacy Stewart. This guy can tell you everything the way it is. I had the pleasure of speaking with him on numerous occasions at the Florida Governor's Hurricane Conference, and even in the conference computer lab...he gave myself, Zack and other members of Radio NHCWX staff a personal thought on the system that would in-part eventually form Eastern Pacific Hurricane Adrian.
This discussion appears that the NHC is currently thinking the potential for Ophelia to loop...and he mentions that "AFTER THAT (96 HOURS) ...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."
That is rather concerning, given that we could then be looking at a well-defined 80-90 mph hurricane...potentially a strong hurricane threatening the Southeastern USA. Hopefully the Dry Mid-Level air will win out as it did with Irene...if not, the worry is of a potent hurricane coming out of Ophelia.
