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Hurricane Frances - Sunday - August 29, 2004 - 9:30 PM
FRANCES MOVING WESTWARD REMAINS A U.S. THREAT IN 6-7 DAYS
CURRENTLY: The intensity of Frances has fallen back some over the last 24 hours. There is a little less overall symmetry but Frances is still a strong hurricane with 125 mph winds, this is now based on recon data as the first flight into Frances was this afternoon. The eye has shrunk from about 20 miles wide 24 hours ago down to 10-12 miles based on latest recon data. It is possible Frances has started another eyewall replacement cycle. If this is the case, look for a leveling off in intensity for next 18-24 hours, followed by another round of intensification beyond that. It will be near impossible to forecast intensity fluctuations over the next 24-72 hours….suffice to say Frances will remain a major Cat 3+ (max winds 115 mph+) for the next 72 hours.
Motion for Frances over the last 24 hours has turned from W.N.W. to due west….current heading is 270 at about 11 mph. In fact, based on latest IR sat pics there may have been a slight jog to the south of west over the last 2-4 hours…but I do not believe that is any kind of trend. Frances is currently moving straight west and that should continue for the next 18-24 hours.
INTENSITY: As mentioned above it will be near impossible to forecast intensity fluctuations over the next 72 hours or beyond. Frances will certainly remain a major hurricane as outlined above.
LONGER RANGE INTENSITY: As I've been saying for the last several days I think the time to watch is the period beyond 72 hours.
Frances will be moving over some of the warmest water in the Atlantic Basin, shear is forecast to be nil, and conditions for her ventilation will become increasingly favorable….I think Frances still has a chance to reach Cat 5 status (155 mph+) beyond the 72 hour period as she makes an approach to the southeast Bahama islands.
Also of some note, while Frances is not exactly a tiny storm now in terms of circulation, she could expand beyond 72 hours into a large and intense hurricane….similar to Floyd (99) and Gloria (85) as they passed the same general area.
Please keep in mind intensity forecasting even in the sort range not an exact science and is even less of an exact science in the longer ranges….but given the data I see in front of me at this point….those intensity numbers have to be considered reachable.
Track to 72 hours: With the current shift to a due west forward motion I will need to adjust track of past few days a little to the left. I Currently expect Frances to pass 75-100 miles north of Anguilla Monday evening. I still expect the center to pass north of the islands but it is going to be dangerously close….and a jog to the south or slight south of west motion could bring the center nearer or perhaps over the northern islands.
AS SUCH….NO ALL CLEAR CAN BE ISSUED AT THIS TIME…YOU FOLKS IN THE NORTHERN ISLANDS MUST CONTINUE TO MONITOR THIS CLOSELY.
To be clear…I still believe center goes north of the islands.
Even with that pass to the north….expect squalls, rough surf, wave and swell action. Expect T.S. warnings to replace the T.S. Watches in effect now, expect watches to be extended further west to British and U.S. Virgin Islands and some Hurricane Watches to go up…all of this over the next 12 to 18 hours.
Beyond 36-48 hours….I do expect a more W.N.W. motion to resume as most guidance indicates at least some relaxation to the ridge north of Frances.
Longer Range beyond 72 hours:
Latest model spread ranges from the latest 12Z 8/29 ECMWF with a hit into Southern 1/3 of Florida…to furthest north NOGAPS giving a threat to SC/NC….UKMET is into central east coast of FL. Most guidance (sans the Euro) though is showing enough of a weakness on the western flank of the sub-tropical ridge to allow a turn more W.N.W. beyond 60-72 hours to maybe even N.W. toward 108-120 hours.
Based on this model support, which has actually increased today….will continue to shade the threat higher toward the SC/NC coast as I have been over the last few days…still thinking in terms of 60/40 chance for a SC/NC hit vs direct landfall in Florida.
Having said that….this does not mean Florida is out of the woods….as I said last night where this turn W.N.W. or N.W. occurs is KEY for Florida….if it occurs late the center could scrape up along the east coast of Florida….but more likely I believe is a track roughly 75-150 miles offshore…this is just a first brush….will refine this as time goes on.
Even if that is correct, Florida would be subject to squalls and wave action. Of course if my thinking is incorrect and the Euro is on the right track then south Florida could be under the gun for a direct hit.
TO BE CLEAR….I AM LEANING AWAY FROM A SOUTH FLORIDA HIT AND LEANING TOWARD A SC/NC LANDFALL. HOWEVER, RESIDENTS ALONG THE FLORIDA EAST NEED TO MONITOR THIS VERY CAREFULLY.
Will need to adjust my Thursday evening position south slightly to 23N - 72.5W….this is slightly south of the latest TPC track. The reason for this adjustment is due to the current westward motion rather than any wholesale change in my thinking.
From that position I am thinking along the lines of a gradual curve up to just east of Nassau in the Bahamas…. then to very near or just east of Andros Island Friday afternoon or evening….from there MY CURRENT THINKING IS A TRACK UP OFFSHORE THE COAST OF FLORIDA…..HOW FAR OFFSHORE? I DON'T KNOW. ALL OF THIS IS SUBJECT TO REVISION OVER THE NEXT FEW DAYS IF NECESSARY.
A POSSIBLE LANDFALL FOR SOUTH FLORIDA MUST REMAIN ON THE TABLE…..BUT I AM LEANING AWAY FROM THAT AT THE MOMENT.
There is absolutely no way to tell what intensity we would be dealing with at that time. I will say this. Conditions will likely remain favorable for a CAT 3+ hurricane. The waters east of Florida are very warm and shear would likely be low. The net result of all that will be is Frances on the upswing or downswing in any kind of intensity fluctuation cycle?
Again….if you live from the Keys to Hatteras PLEASE stay tuned for future updates.
More tomorrow evening….