Saturday, August 28, 2004


FRANCES NOW A CATEGORY 4 HURRICANE...AND WILL BE CAT 5 BY MONDAY OR TUESDAY.

CAROLINAS AND MID-ATLANTIC STATES AT GREATEST RISK
LANDFALL IS NOW PROJECTED FOR SUNDAY, SEPT 5 IN THE LATE AFTERNOON

TWO OTHER TROPICAL SYSTEMS NEAR THE CAROLINA COAST AND WILL INFLUENCE THE PATH OF FRANCES TO DIRECT HER TOWARD THE U.S.

IF YOU LIVE NEAR WATER OR HAVE PROPERTY ON THE WATER, BEGIN PLANNING NOW....BECAUSE THIS MAY BE ISABEL ALL OVER AGAIN.

The National Hurricane Center is already resigned to the fact that this storm will reach Category 5 status by early next week, with sustained winds of 160 mph.

What complicates the matter is the is the emergence of no one, but TWO additional tropical systems... Tropical Storm (almost Hurricane) Gaston is east of Charleston, and what is a developing tropical wave may eventually become Hermine. Gaston will probably be a Hurricane by the time it reaches the Charleston area, and will drench the region from the Carolinas to the Chesapeake Bay with tropical rains in the time period from Tuesday through Friday. Not a total flood washout situation, but enough to saturate the ground in advance of Frances' arrival. This is exactly the setup that happen in 1999 with Dennis and then Floyd, followed by 2003 with a tropical depression that sat along the coast right before Isabel arrived.

Recall the headline from early August: "TROPICAL STORM ALEX A SIGN OF THINGS TO COME." All storms this seaso have continued to surprise us with erratic movement or rapid, unexpected strengthening.

The other complicating (or simplifying factor, depending on your point of view) is that due to the counter-clockwise rotation of these systems...they will be inadvertently creating a channel into which Frances will move. However the upper-level outflow at the top of the storm ends up spinning the other direction... clockwise, because it is in a high pressure environment. Things get weird when you get two or more tropical systems in close proximity to the other. In the right orientation, (where Gaston is to the west of TD # 8), the outflow from one system can actually serve to provide moisture to the other system, thereby strengthing it. The residual outflow from both systems will get entrained in the inflow of Frances, and because they are all far enough apart from each other, all three can in effect strengthen without negatively affecting the other.

The only unknown factor is what will happen if the unlikely comes true. The longer these two systems stay over open warm water, the more possible they do become hurricanes. That would change the whole equation, because then the water ahead of Frances along the coast would get disturbed enough that it would be slightly cooler when Frances arrives. That scenario would be good news for all of us on the coast... as it would cause Frances to weaken before landfall.

However, there is ample warm water between the coast and the hurricane. Were Frances to reach the Carolina coast as a Category 3, all interests from Myrtle Beach to the Jersey Shore should be prepared for potential tropical storm force winds of 40-60 mph. Land areas within 50 miles of landfall will experience winds well in excess of 75 mph.

I will keep hammering away at this point because we tend to forget.... the storm surge from Isabel in the Chesapeake Bay was observed to be 2-3 feet ABOVE the projected surge of 4-6 feet (6-8 feet in the southern bay, 4-6 feet in the northern bay). Think of what it might have been like had Isabel arrived as a Category 3... and then you know what we are up against with Frances.

The next time I update on Sunday in the afternoon, this storm will probably be a strong Cat 4. Whenever the posted "gust speed" is considerably higher than the sustained speed, it is an indication the storm is still in a strengthening phase. Winds right now are already gusting to Cat 5 strength (160 mph) and I would not be surprised if we see Max winds at 155 by Sunday night with gusts to 175.

The stronger it gets the closer to land, the longer it will take for wind speeds to decrease once it crosses land... and the higher potential for flooding and damage. That's why there is concern about strong wind speeds with a distant hurricane.

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