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8/27/04 FCST: Frances (Atlantic)

The GA coast is still under the gun, no doubt. I thought the models were converging on a solution here but the opposite is happening. One model takes Frances over Cuba while another makes landfall on the Outer Banks for a steamroll up the DC-NYC corridor.

GFS is really showing Frances bomb out right before landfall. I know the GFS doesn't handle hurricane intensity very well, but according to the model it is most intense just as it strikes land.
 
GFS is really showing Frances bomb out right before landfall. I know the GFS doesn't handle hurricane intensity very well, but according to the model it is most intense just as it strikes land.

It will show this every time - as will the other models - because the initialized model state won't have the correct intensity of the system to start the model run with. Since the model starts with a weak tropical system, and the environment is favorable for a hurricane, the system will rapidly intensify in the model. A such, the operational GFS is not a very useful tool for examining the hurricane's intensity.

Glen
 
Blech...as noted, the models are all over the place again. Well, hopefully they converge on some sort of solution by Thursday morning, but we must leave Norman now in order to get the radar trucks in position. This will be my first hurricane chase, so I hope we manage to make a good intercept. Clearly, this will boil down to the amplitude of the trough developing over the southern plains and the downstream ridge. Not an easy forecast...let's cross our fingers it works out for the people in the path. Be safe, and see you all on the other side!
 
Thanks for the clarification on how the GFS handles the hurricane. I didn't realize it has to basically reform it for every model run.

Good luck to the hunters who are getting on their way.
 
........hello all......
first post, long time reader

Here's your answer in Hurricane Marilyn...

"Marilyn continued moving northwestward over the northeastern Caribbean Sea. It hit the U.S. Virgin Island during the afternoon and night of the 15th as a strengthening Category 2, nearly Category 3, hurricane. The Hurricane Hunters reported hail, an unusual occurrence for tropical cyclones. They noted an eye of 20 n mi diameter. The strongest part of the hurricane, the eyewall to the east and northeast of the center, passed over St. Thomas. Maximum one-minute surface winds at that time were close to 95 knots."

http://www.nhc.noaa.gov/1995marilyn.html

Johnnie
 
latest (31/1730z) hurricane hunter info drops the pressure to 942mb, however they only report a max flight-level wind of 105kt? That's quite a discrepancy - 942mb should support winds of at least 115kt if i'm not mistaken. Frances has continued to improve in satellite appearance also as the eye is contracting and the CDO cloud tops cool.

Any thoughts on the pressure/wind discrepancy?

hurricane hunter vortex message here: http://www.nhc.noaa.gov/text/MIAREPNT2.shtml?
 
Any chasers going to any of the islands in the path? I seem to remember
several chasers went island hopping before Andrew?

Mike
 
latest (31/1730z) hurricane hunter info drops the pressure to 942mb, however they only report a max flight-level wind of 105kt? That's quite a discrepancy - 942mb should support winds of at least 115kt if i'm not mistaken. Frances has continued to improve in satellite appearance also as the eye is contracting and the CDO cloud tops cool.

Any thoughts on the pressure/wind discrepancy?

hurricane hunter vortex message here:http://www.nhc.noaa.gov/text/MIAREPNT2.shtml?

It may have just been an error... I checked the link, and the latest message has pressure at 940mb, with: "MAX FL WIND 137 KT NW QUAD 1735Z. SMALL HAIL IN SW EYEWALL."

The motion in the eye on that satellite loop is incredible!

The models have been signficant changes in their forecasts, for the most part. GFS generally brings the hurricane considerably farther east than earlier, with landfall in SC. Meanwhile, the ECMWF continues its forecast of bringing the hurricane across the far southern tip of FL and into the Gulf as a strong hurricane. There is pretty poor consistency as others have noted, which, combined with the acure approach angle, will make landfall forecasts incredibly difficult. Thank goodness I'm not the one in charge of evacuating thousands (millions?) of people...
 
I'm watching the 18Z GFS come in with sad fascination. The western trough is not gonna make it -- upstream energy is holding it back. Most of the southeast and midwest is water-logged. What a mess. :(
 
I'm still thinking it will curve north towards the Carolinas. I just can't see the ridge holding on that long. I guess we'll see, but if I was chasing I'd be heading to South Carolina to start, personally. Hopefully it will weaken as it curves like they usually do..
 
I don't think this has been posted yet, but there is are a few phenomenal sat pics of Frances at http://rapidfire.sci.gsfc.nasa.gov/gallery/ ... Specifically, check out http://rapidfire.sci.gsfc.nasa.gov/gallery...4.1445.250m.jpg (250m resolution sat pic of the hurricane --> ~6.5mb) ... Additionally, keep an eye on http://www.osei.noaa.gov/Events/Current/ , as they add a few pics a day sometimes of high-resolution satellite imagery.

8pm Local intermediate advisory maintains 939mb eye with 140mph winds. I'm still amazed by the nearly-perfect appearance of the eye!
 
The GFS shows Frances' remnants tracking over western NC, all of WV, and most of Ohio. Still very early to make a call, but this is a major concern. Tropical rainfall in mountains means catastropic flash flooding and landslides.
 
Those high res images are amazing. It looks like it could swallow up Puerto Rico. Within 24 hours we could see an unprecedented evacuation. Yes, millions not thousands. For those of you chasing remember some highways only go one way during an evacuation...inland.
 
Here's another fun exercise:

Run a 20 or 25 image loop from here:

http://wwwghcc.msfc.nasa.gov/GOES/goeseasthurrwv.html

Speed it up. Fast.

Now, consider that the NHC's latest track forecast (5PM EDT, 8-31) carries Frances across -22.5W and 71.0N.

Think it will make it that far north by -22.5W now?

Unless those lat/lon overlays on the imagery are positioned wrongly a bit, I'd say no way.

While you're looking at the loop, also look for the trough that's supposed to come to S Florida's rescue.

I guess I see it materializing in TX/LA, but is "The Cavalry" gonna make it in the nick of time?

Rut roh.

Bob
 
Dammit, yeah....

22.5N, 71.0W.

I used the negative because....oh, N/M, lol.

[edit] And, yep, it does look right on track from that loop. I like that. I hadn't seen that one before. Just goes to show how difficult it is to evaluate tracks from the other imagery.
 
MAXIMUM SUSTAINED WINDS ARE NEAR 140 MPH...220 KM/HR...WITH HIGHER
GUSTS. THIS MAKES FRANCES A CATEGORY 4 HURRICANE ON THE
SAFFIR-SIMPSON HURRICANE SCALE. WHILE FLUCTUATIONS IN INTENSITY
ARE EXPECTED DURING THE NEXT 24 HOURS...FRANCES COULD STILL
INTENSIFY A LITTLE MORE BEFORE REACHING THE HURRICANE WARNING AREA.

!!!!!

It can still intensify?! The pressure, in the meantime, is now down to 935 mb. Interestingly, Hugo in 1989 was down to 934.

This IR "Storm floater" image from NOAA —
df4aec44f056a731338f438c472cfc31.jpg — looks pretty interesting, too . . . especially in the way that the coldest cloud top temps, rather than consolidating in a single ring around the eye, have sprawled out into a 9-shape. Does anyone know if that means anything?
 
looks pretty interesting, too . . . especially in the way that the coldest cloud top temps, rather than consolidating in a single ring around the eye, have sprawled out into a 9-shape. Does anyone know if that means anything?

While there is no way to know this for certain, theory of hurricanes would suggest that this pattern is following from the shedding of waves from the hurricane eyewall. There is a highly concentrated ring of "spin" (vorticity) just inside of the radius of maximum winds of the hurricane, and this ring is often unstable and can radiate energy in the form of waves outward from the inner ring. These waves can act to enhance vertical motion, and cause deeper convection (appearing as colder cloud tops). If you look closely at the image, you'll note two distinct bands of colder cloud tops coming out of the center (a wavenumber 2 pattern). This is roughly the correct wave pattern for this type of instability (known as a vortex Rossby wave).

Glen
 
First landfall is just a few hours away. Anybody have links to real-time weather in the Turks & Caicos and Bahamas?

How about official government sites for those islands and respectable news outlets? Everything on the web seams to revolve around tourism.


Edit: Anybody up for an on-going NOW thread on Frances, maybe in a few hours? I think we should keep the forecast thread up for the mainland, but NOW would be appropriate for the islands.
 
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