ATL: BARRY - Post-Tropical - Discussion

[sphelps8681]

Where in the world is our buddy, wxman57?

Dealing with all his clients I am sure.

[Aric Dunn]

The gradual craw of the preexisting vorticity towards the Gulf of Mexico is in progress this afternoon. Satellite observations of low-level cloud motions over the Southeastern United States and surface observations show that winds at the surface and in the low-levels are backing over southwestern Georgia and the Florida Panhandle, an indication that the low-level rotation is stretching towards the Gulf. This short-term evolution has been well-forecast by high-resolution mesoscale guidance. Indeed, the latest vorticity analyses from CIMSS show that the 850 hPa and 700 hPa vorticity maxima have shifted southwards to around the Florida/Georgia border in the vicinity of Tallahassee. The spin at the mid-levels is still centered farther west over southern Alabama, but model guidance suggests that this should drift south into the Gulf and allow time for the low-level vorticity to stack a bit better under the spin aloft.

Light convection is currently in progress over the Florida Panhandle which will help modify the current wind field. Expect an increase in convection over the northeastern Gulf of Mexico at the oceanic diurnal maximum in the hours leading up to dawn tomorrow morning. A surface low will probably take more time to organize - perhaps over the course of several days - but an elevated and closed circulation at about the 850hPa level should be over or emerging into the Gulf by tomorrow evening.

174 kB. Source: Storm Prediction Center :: The surface wind field is still a mess, but don't expect a whole lot at sea-level until more coalescing and better alignment of the circulation aloft happens over the warm Gulf waters.
https://i.imgur.com/6m8gcol.png

Yeppers But I dont think it will take all to long to develop

[wxman57]

With the NHC showing so much confidence in development, I would expect them to issue PTC advisories as early as tomorrow.

Their guideline is that a disturbance must have a high chance of development and be within 48 hours of landfall. If it is predicted to make landfall on Saturday, then the NHC may not initiate advisories until Wednesday afternoon at the earliest or perhaps Thursday morning.

For now, I'm thinking landfall SW LA as a strong TS or Cat 1 early afternoon Saturday. Models are converging on that area. LOTS of uncertainty as to how quickly this could get organized in the Gulf, which affects its eventual intensity.

[ronjon]

What a coup for the upgraded Euro if this develops into a hurricane and heads towards the NW Gulf. All there is right now is a swirl of cumulus over GA. Not a good start for the new GFS if it does develop but as we can see seems the old GFS may be even more off so at least there is progress with the model.

Yeah the Euro was the first model to pick up on this system's development. It hinted at development all the way back to the 3/4 of July. Would certainly be a nice start to the season for the Euro if this system does develop, which looks increasingly likely.

A little early to be patting the Euro on the back yet. GFS solution could still happen. Depends how far offshore and whether northerly shear impacts development. Guidance seems to at least initially show a broad low developing. If that is the case, it will take awhile to develop.

[StruThiO]

 https://twitter.com/DerekOrtt/status/1148354445236944896

[USTropics]

Hurricane Two from 1940 could be a good analog. I believe origin was very similar (frontal boundary draped down into the GOM at the end of July/1st week of August).

[wxman57]

The 1943 "Surprise Hurricane" may be a good analog, too. It developed from a disturbance that was inland over the southeast U.S. (in July). By the time it made landfall in Galveston/Houston, it was a strong hurricane, stronger than the U.S. admitted during the war. Alicia did something similar in August of 1983.

https://en.wikipedia.org/wiki/1943_Surprise_Hurricane

[Hybridstorm_November2001]

Everyone in the path please keep safe. This could be the nightmare scenario many forecasters have always feared: a system forms that the models don't have a good handle on, it then goes from a nothing into a major hurricane so fast people don't have adequate time to evacuate at risk coastal areas. My fervent hope is this one doesn't bomb out in the GOM once it becomes established or better yet it doesn't become established in the first place. Let's all hope for the best.

[SoupBone]

The 1943 "Surprise Hurricane" may be a good analog, too. It developed from a disturbance that was inland over the southeast U.S. (in July). By the time it made landfall in Galveston/Houston, it was a strong hurricane, stronger than the U.S. admitted during the war. Alicia did something similar in August of 1983.

https://en.wikipedia.org/wiki/1943_Surprise_Hurricane

What your posting suggests is a surprise, quick ramp up in intensity.

[TheStormExpert]

Everyone in the path please keep safe. This could be the nightmare scenario many forecasters have always feared: a system forms that the models don't have a good handle on, it then goes from a nothing into a major hurricane so fast people don't have adequate time to evacuate at risk coastal areas. My fervent hope is this one doesn't bomb out in the GOM once it becomes established or better yet it doesn't become established in the first place. Let's all hope for the best.

Didn’t we just have a similar situation last year with Michael?

[Hybridstorm_November2001]

Everyone in the path please keep safe. This could be the nightmare scenario many forecasters have always feared: a system forms that the models don't have a good handle on, it then goes from a nothing into a major hurricane so fast people don't have adequate time to evacuate at risk coastal areas. My fervent hope is this one doesn't bomb out in the GOM once it becomes established or better yet it doesn't become established in the first place. Let's all hope for the best.

Didn’t we just have a similar situation last year with Michael?

Yes, the models were all over the place for a long time with Michael as I recall. The difference here is this one could form and then deepen quicker.

[AnnularCane]

Everyone in the path please keep safe. This could be the nightmare scenario many forecasters have always feared: a system forms that the models don't have a good handle on, it then goes from a nothing into a major hurricane so fast people don't have adequate time to evacuate at risk coastal areas. My fervent hope is this one doesn't bomb out in the GOM once it becomes established or better yet it doesn't become established in the first place. Let's all hope for the best.

That was a deep down concern for me when I lived in the NOLA area.

[oldframe]

Levi posted a new TT video:

https://www.youtube.com/watch?v=njwiXKp8rEA

[pcbjr]

What are the limiting factors for development of this system?

Georgia, for one ...

[Aric Dunn]

interestingly the local seabreezes from florida panhandle and east coast are playing a decent role in creating the vorticity/low just NE of Tallahassee .

[ronjon]

interestingly the local seabreezes from florida panhandle and east coast are playing a decent role in creating the vorticity/low just NE of Tallahassee .

You can make out the broad low in SW Georgia centered near Albany by looking at the rotation of convective storms on the Tally RAD.

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Mon Jul 8 2019

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A trough of low pressure located over south-central Georgia is
producing disorganized showers. This disturbance is expected to
move southward or southwestward during the next day or two, and a
broad area of low pressure is forecast to form over the northeastern
Gulf of Mexico on Wednesday. Environmental conditions are expected
to be conducive for development and a tropical depression is likely
to form by the end of the week while the low moves slowly westward
across the northern Gulf of Mexico. Regardless of whether or not a
tropical cyclone develops, this system has the potential to produce
heavy rainfall along portions of the northern and eastern U.S. Gulf
Coast later this week. For more information about the rainfall
threat, please see products issued by your local weather forecast
office and the NOAA Weather Prediction Center. Interests along the
Gulf Coast from the Upper Texas coast to the western Florida
peninsula should monitor the progress of this system.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...high...80 percent.

$$
Forecaster Cangialosi

[StruThiO]

 https://twitter.com/webberweather/status/1148371563206434817

[Aric Dunn]

interestingly the local seabreezes from florida panhandle and east coast are playing a decent role in creating the vorticity/low just NE of Tallahassee .

You can make out the broad low in SW Georgia centered near Albany by looking at the rotation of convective storms on the Tally RAD.

looking at storm motion and surface obs. appears west of Valdosta.

[Hurricaneman]

If it keeps heading on it’s current trajectory it could be in the GOM near Cedar Key