ATL HANNA: Extratropical - Discussion

#2141 Postby **jlauderdal** » Mon Sep 01, 2008 11:44 am

fasterdisaster wrote:Looks like I'm back in watch mode.

i have been sleeping with one eye open the last two weeks and more to come with hanna and td9

HurricaneRobert · #2142 Postby **HurricaneRobert** » Mon Sep 01, 2008 11:44 am

Don't see any eye yet, but it looks impressive.

apocalypt-flyer · #2143 Postby **apocalypt-flyer** » Mon Sep 01, 2008 11:44 am

cpdaman wrote:1248 and 1258 recon data sets Should have this storms NE quad

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

i'm am afraid she MAY be undergoing RI, i hope not

You know I didn't want to use those two letters at any point here but I have a similar feeling at the moment.

captain east · #2144 Postby **captain east** » Mon Sep 01, 2008 11:45 am

What RI? Rapid Intensification?

#2145 Postby **HURAKAN** » Mon Sep 01, 2008 11:45 am

captain east wrote:What RI? Rapid Intensification?

Yes.

Tampa Bay Hurricane · #2146 Postby **Tampa Bay Hurricane** » Mon Sep 01, 2008 11:46 am

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

Based on IR black cloud tops and satellite, this system is undergoing rapid intensification.

#2147 Postby **vbhoutex** » Mon Sep 01, 2008 11:47 am

cpdaman wrote:1248 and 1258 recon data sets Should have this storms NE quad

The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

i'm am afraid she MAY be undergoing RI, i hope not

What makes you think so. What parameters have you seen to indicate this?

#2148 Postby **gatorcane** » Mon Sep 01, 2008 11:48 am

Can someone answer what the anticyclonic turning I see is just West of the FL peninsula...?

That seems to be a high pressure system and some kind of narrow ridge over Florida....that seperates Hanna and Gustav.

Wonder if that will impact the steering currents for Hanna?

http://www.ssd.noaa.gov/goes/east/tatl/loop-avn.html

#2149 Postby **Blown Away** » Mon Sep 01, 2008 11:48 am

Does anybody think there will be significant changes with the forecast track? Intensity changes are a yes.

#2150 Postby **jlauderdal** » Mon Sep 01, 2008 11:49 am

Tampa Bay Hurricane wrote:The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or storm2k.org. For official information, please refer to the NHC and NWS products.

Based on IR black cloud tops and satellite, this system is undergoing rapid intensification.

actual pressure drops will dictate whether or not it is RI according to the definition:
Explosive Deepening:
A decrease in the minimum sea-level pressure of a tropical cyclone of 2.5 mb/hr for at least 12 hours or 5 mb/hr for at least six hours.

Rapid Deepening:
A decrease in the minimum sea-level pressure of a tropical cyclone of 1.75 mb/hr or 42 mb for 24 hours.

:double:

fasterdisaster · #2151 Postby **fasterdisaster** » Mon Sep 01, 2008 11:49 am

Probably a shift to the south in the track I'd say

NEXRAD · #2152 Postby **NEXRAD** » Mon Sep 01, 2008 11:51 am

I don't suspect rapid intensification is occuring, as I've not noticed a significant eye signature at all on IR, IRWV, visible, or microwave satellite imagery. Furthermore, the upper level conditions are not favorable for rapid intensification. The roughly 20-knot northerly shear aloft is working to aid divergence (based on the anticyclonic flow about UL ridging in the Gulf and the flow about a trough base to the north). However for rapid intensification, you usually want to see a dual channel outflow.

Based on the latest recon and satellite information, I'd pin Hanna at 60 or 65 knot intensity, but wouldn't expect it to leap rapidly beyond minimal hurricane strength this afternoon.

- Jay

#2153 Postby **deltadog03** » Mon Sep 01, 2008 11:51 am

This is what I was wondering about the other day on why the models kept strengthening this under the is harsh shear. It appears the hanna is pushing through the shear from gustav, but just to the west it can get under that skinny ridge over fl. This is what Stewart was talking about with the dual outflow channels being a possibility....IMO

HurricaneRobert · #2154 Postby **HurricaneRobert** » Mon Sep 01, 2008 11:52 am

I think a small eye shows up, then RI follows. So far I don't see any eye with Hanna.

#2155 Postby **StJoe** » Mon Sep 01, 2008 11:52 am

gatorcane wrote:Can someone answer what the anticyclonic turning I see is just West of the FL peninsula...?

That seems to be a high pressure system and some kind of narrow ridge over Florida....that seperates Hanna and Gustav.

Wonder if that will impact the steering currents for Hanna?

http://www.ssd.noaa.gov/goes/east/tatl/loop-avn.html

Could it be Gustav's southerly outflow mixing with Hanna's northerly flow that is creating that?

NCWeatherChic · #2156 Postby **NCWeatherChic** » Mon Sep 01, 2008 11:52 am

Question here...at a 77kts or so FL winds for Hanna, what would that say for surface winds? How does this convert? Hope that made sense. I know what I am trying to say but my head wont allow me to get the words out correctly after the hydrocodone I took (just had surgery). :wink:

x-y-no · #2157 Postby **x-y-no** » Mon Sep 01, 2008 11:53 am

gatorcane wrote:Can someone answer what the anticyclonic turning I see is just West of the FL peninsula...?

That seems to be a high pressure system and some kind of narrow ridge over Florida....that seperates Hanna and Gustav.

Wonder if that will impact the steering currents for Hanna?

http://www.ssd.noaa.gov/goes/east/tatl/loop-avn.html

Yes. That's the reason Hanna is moving so slowly. To me, it looks very much as the GFS has depicted it.

#2158 Postby **fci** » Mon Sep 01, 2008 11:54 am

fasterdisaster wrote:Probably a shift to the south in the track I'd say

No, that would be deemed "unacceptable"
Sorry....

fasterdisaster · #2159 Postby **fasterdisaster** » Mon Sep 01, 2008 11:54 am

She definitely has a forming eye. I don't know how you can miss it.

NEXRAD · #2160 Postby **NEXRAD** » Mon Sep 01, 2008 11:54 am

NCWeatherChic wrote:Question here...at a 77kts or so FL winds for Hanna, what would that say for surface winds? How does this convert? Hope that made sense. I know what I am trying to say but my head wont allow me to get the words out correctly after the hydrocodone I took (just had surgery).

The 77 knots flight level translates to a rough 61 to 69 knot surface wind. The general rule is to reduce the flight level winds by 10 to 20 percent to get an estimate on surface winds, though the percentage varies depending on the actual flight level.

- Jay

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