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Hurricane Frances - Saturday - August 28, 2004 - 9:30 PM
INTENSE CAT 4 FRANCES CHURNING W.N.W. THREAT OF U.S. LANDFALL LOOMING IN THE 7 DAY RANGE
CURRENTLY: Frances was starting to undergo an eyewall replacement cycle at this time last night and finished up that cycle this morning…..the small, tight 10 mile wide eye has been replaced with a wider (20-25 mile) stadium effect type eye during this afternoon and evening.
After this eyewall replacement cycle finished Frances began to ramp up further in intensity. Frances is currently a Cat 4 hurricane with 135 mph winds. Not sure what else can be said….Frances is a classic text book hurricane at this time….perfect symmetry, nothing short of excellent outflow in all quadrants and perfect CDO with the eye embedded right in the center.
During the afternoon Frances moved as much NW as she is going to move…the latest satellite loops clearly show she has started turning back to the WNW….on a 295-300 degree heading…forward speed has also slowed slightly over the last few hours.
INTENSITY: It is no secret I have underestimated the intensity of Frances over the last few days. Was expecting a 105-110 mph at this time and Frances is at 135 mph. Moving forward…. conditions look ideal for Frances to at least hold her own for the next 24 - 48 hours…no eyewall replacement cycle would be expected for the next 24 hours or so…but once we get into the 24-36 hour time frame we could see another eyewall replacement cycle, this is common in intense hurricanes…they are however next to impossible to time with any degree of accuracy. Thus expect Frances to maintain a status quo for next 24 hours then perhaps fall back some in the 36-48 hour time range.
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 if Frances is to reach CAT 5 status it will happen as she moves north of Puerto Rico and Hispaniola and nears the S.E. Bahamas. I think at that point we could see a 150 to 160 mph hurricane.
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: No real change to prior thinking from last several days. Still expect Frances to pass 125 miles north of Anguilla Monday evening on a W.N.W. heading….then continue W.N.W. through Tuesday evening passing north of Puerto Rico. On this track the northern islands will be spared a direct hit but squalls, wave and swell action can be expected.
STILL CAN'T ISSUE AN ALL CLEAR FOR THE NORTHERN ISLANDS…THAT COULD COME TOMORROW EVENING…BUT AT THIS POINT CONFIDENCE IS MODERATE TO HIGH OF A PASS TO THE NORTH AT A SAFE DISTANCE.
Latest models range from the GFS on the left…with a track through the straits of Florida..to the NOGAPS/GFDL taking more of an aim on the coast of the Carolinas…..other guidance in essentially in between…with the UKMET bringing Frances into extreme south Florida…even the latest ECMWF has dropped its potential out to sea solution from 12Z Friday and it too has a dangerous solution for central and south Florida.
Longer Range beyond 72 hours: As mentioned above the model spread is from south Florida to Cape Hatteras….that has really been on the table for days now…so the time to start narrowing that down is fast approaching. The window of opportunity for a safe recurvature off the east coast is essentially closed.
Thinking here…as it was last night at this time is still for a 60/40 chance that the Carolinas are at higher risk than Florida. My thinking remains that there will be enough of a weakness on the western flank of the sub-tropical ridge to allow a more northward turn up off the east coast of Florida. Backtracking a bit….still expect a Thursday position near 24N/72.5W….this is slightly north of the official TPC track.
From that position I am thinking along the lines of a gradual curve up off the east coast of Florida into an anticipated weakness on the western side of the ridge. How far off the east coast of Florida….I don't know….it could be dangerously close….beyond that would expect a movement toward the SC/NC coast.
The other scenario is that the ridge builds westward more strongly north of Frances….a possibility somewhat higher than this time last night as when T.S. Gaston departs it could force that to happen…this would drive Frances into south Florida….not leaning that way at the moment…but it is on the table.
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….