ATL HANNA: Extratropical - Discussion

[cpdaman]

i think this matches the SE trend of center fixes per recon

http://adds.aviationweather.gov/satelli ... g&itype=ir

Maybe she is begining her loop like on HWRF.

look also at turk and caicos conditons (winds and pressure indicated a storm growing closer)

SUSTAINED winds at 61 in turks and caicos gust to 64 (this station has been accurate all nite into today so i would say it is very accurate) ....pressure down to 984 as well

http://www.wunderground.com/weatherstat ... =IPINECAY2

hope our poster there is safe!

[cpdaman]

another station also reporting

sustained wind of 50 on 6 minute intervals for the better part of an hour

not the 61 sustained at other station but dang close enough

http://www.wunderground.com/weatherstat ... ?ID=MD0758

and yes this should be accurate (has been all nite and into today)


also trending back to a more circular visible loop as it slides SE away from gustav's shear streak

http://adds.aviationweather.gov/satelli ... &itype=vis

[storms in NC]

I think Floyd was the last biggest storm. He was huge

[AJC3]

More concerned about her slipping under Florida and transiting into the Gulf of Mexico. Trend of the UKMET is west, and that model has been pretty good so far this year. I just wish someone would explain to me how she's going to transit north? I thought there was a blocking high in place along the east coast.

That's been pretty well explained in the past couple TCD's. The combination of a large deep layer high over the eastern CONUS coupled with a cutoff low over the western ATLC will block Hanna from moving much over the next couple of days. After that...the eastern CONUS high weakens while the upper low lifts out, and the Bermuda ridge builds westward. The westward building ridge is expected to induce a NW to NNW motion from day 3 onward. The key determining factor in Hanna's eventual track will be this ridge...how quickly and strongly it builds westward in the wake of the departing low.

As you've seen, thus far the general consensus of guidance (UKMET being the most notable exception) has been for a track very close to the east coast of FL...then moving inland somewhere in the SAV-Myrtle Beach area. By no means is that even close to being set in stone - there's quite a bit of uncertainty, considering the intensification of Hanna today, which was occurring during the time the 12Z guidance suite initialized.

Since I'm not a big fan of intermediate runs (18Z, 06Z) of the GFS, I'll be more interested in the 00Z globals.
Looks like a close call for FL, no matter how you slice it.

[HurricaneHunter914]

URNT12 KNHC 011858
VORTEX DATA MESSAGE AL082008
A. 01/18:34:10Z
B. 22 deg 14 min N
072 deg 16 min W
C. 850 mb 1299 m
D. 58 kt
E. 132 deg 28 nm
F. 211 deg 074 kt
G. 132 deg 035 nm
H. 984 mb
I. 16 C/ 1533 m
J. 20 C/ 1523 m
K. 19 C/ NA
L. NA
M. NA
N. 12345/8
O. 0.02 / 5 nm
P. AF301 0208A HANNA OB 16
MAX FL WIND 74 KT SE QUAD 18:23:00 Z
BROAD WIND AND PRESSURE CENTER WITH FLATTER GRADIENT THAN PREVIOUS FIXES

What does that mean?

[Steve H.]

Question for the forum. Is Hanna moving at all at this point or is she stationary? Just ask cause I'm short on time and am running out to get some plywood. Thanks.

[mawolf3]

Florida caught between two flows.

Does that mean Hanna has a chance to go right through Florida?

More concerned about her slipping under Florida and transiting into the Gulf of Mexico. Trend of the UKMET is west, and that model has been pretty good so far this year. I just wish someone would explain to me how she's going to transit north? I thought there was a blocking high in place along the east coast.

They are predicting that high to weaken and Hanna will excelerate to the nothwest around it.

[Weatherboy1]

I wonder if we might not be seeing the start of the potential cyclonic loop some of the model runs have been hinting at. Last couple of recon fixes showing a S to SSE move in the area of lowest pressure, so that coule be part of a looping pattern. Not sure.

[AJC3]

BROAD WIND AND PRESSURE CENTER WITH FLATTER GRADIENT THAN PREVIOUS FIXES

What does that mean?

It simply means the center is broader than during previous passes. The pressure gradient (the rate of pressure change [fall] as one heads toward the center) determines how quickly winds increase as one heads toward the center.

[mawolf3]

http://cimss.ssec.wisc.edu/tropic/real- ... 8dlm2.html

Florida being protected by that invisible dome

[CourierPR]

I wonder if we might not be seeing the start of the potential cyclonic loop some of the model runs have been hinting at. Last couple of recon fixes showing a S to SSE move in the area of lowest pressure, so that coule be part of a looping pattern. Not sure.

Perhaps center relocation is due to the organizing process.

[HurricaneHunter914]

BROAD WIND AND PRESSURE CENTER WITH FLATTER GRADIENT THAN PREVIOUS FIXES

What does that mean?

It simply means the center is broader than during previous passes. The pressure gradient (the rate of pressure change [fall] as one heads toward the center) determines how quickly winds increase as one heads toward the center.

Thanks. So a flatter gradient would mean?

[cpdaman]

down to 983.3 at station.....................SW winds howling

http://www.wunderground.com/weatherstat ... =IPINECAY2

[Sanibel]

If it moved mostly west and then juggled SSE that would conform to the start of a stall/cyclonic loop. That NW movement would be the expected track from here.

Now if the High builds further west than expected a Florida east coast skimmer could be an unexpected surprise if those cold tops translate to intensity.

[cpdaman]

If it moved mostly west and then juggled SSE that would conform to the start of a stall/cyclonic loop. That NW movement would be the expected track from here.

Now if the High builds further west than expected a Florida east coast skimmer could be an unexpected surprise if those cold tops translate to intensity.

Well AJC3 made it pretty clear this is not going anywhere significantly for 36 hours so......any turn to a NW "drift" later would be just that IMO (drift)

[El Nino]

down to 983.3 at station.....................SW winds howling

http://www.wunderground.com/weatherstat ... =IPINECAY2

106 km/h, 983mb is NOT the min pressure !

[GTStorm]

Yeah, if it DOESN'T hold, I still just don't see the NHC's Savannah landfall. Not buying it. I'm sticking with NC or S. FL.[/quote]

Right with you. For Savannah, the best place to be 4-5 days out is right in the middle of the cone. A pick-me-up trough should be digging along any day now. They always do. If I were in Myrtle Beach or anywhere north of there I'd be worried.

[RL3AO]

Thanks. So a flatter gradient would mean?

Lower winds

[Sanibel]

Well AJC3 made it pretty clear this is not going anywhere significantly for 36 hours so......any turn to a NW "drift" later would be just that IMO (drift)

Sure. By the way, Hanna is a female name...

[HURAKAN]

191630 2214N 07224W 8427 01364 9832 +223 +170 025006 008 020 002 00
191700 2213N 07223W 8430 01361 9832 +221 +170 317003 004 021 002 03

extra 983 mb