ATL: MINDY - Post-Tropical - Discussion

[MGC]

Sure does look like there is a bit of a spin associated with 91L this morning....MGC

[drezee]

 https://twitter.com/andretrotter/status/1435236937158340618

[drezee]

https://twitter.com/andretrotter/status/1435205015048646666

I don’t see the “screaming shear” where this surface circulation is forming near 23.5N and 93W.

It is being sheared. You see no upshear convection...

[Dean4Storms]

https://twitter.com/andretrotter/status/1435205015048646666

I don’t see the “screaming shear” where this surface circulation is forming near 23.5N and 93W.

It is being sheared. You see no upshear convection...

When I think screaming shear I think over 30mph.

[wxman57]

https://twitter.com/andretrotter/status/1435205015048646666

I don’t see the “screaming shear” where this surface circulation is forming near 23.5N and 93W.

Look at the cirrus clouds racing from west to east across the disturbance. Lots of shear. Development in the Gulf is quite unlikely. Only a very slight chance of development once it moves off the East Coast and heads out to sea. GFS indicates very strong shear building across the Gulf by this weekend. May last for the next couple of weeks.

[drezee]

I don’t see the “screaming shear” where this surface circulation is forming near 23.5N and 93W.

It is being sheared. You see no upshear convection...

When I think screaming shear I think over 30mph.

But we all agree that there is no "standard" for that adjective...so....ok...lets move on

[ronjon]

We're getting heavy tropical downpours along the nature coast of Florida already this morning well removed from the disturbance. Looks like at a minimum its pulling up deep tropical moisture now. Current shear analysis does show only 5-10 kts in the central GOM with higher shear along the northern gulf cost and south of the disturbance. There my be a sweet spot opening up for some limited development. It is afterall, peak of the season.

[Frank P]

Here is one LLC that looks looks like it is trying to form: 23.2n and 93.7w

[chaser1]

We're getting heavy tropical downpours along the nature coast of Florida already this morning well removed from the disturbance. Looks like at a minimum its pulling up deep tropical moisture now. Current shear analysis does show only 5-10 kts in the central GOM with higher shear along the northern gulf cost and south of the disturbance. There my be a sweet spot opening up for some limited development. It is afterall, peak of the season.

Sweet spot indeed. During those years where the background state suggests a general overall favorability, I tend to not look at those areas where conditions are least favorable but more broadly view "how" and "where" development might occur in spite of those negative factors. Upper level shear is a factor however continued convective bursting generally can also help deflect the strong shear and help build somewhat of a more relaxed flow as well. I see 91L as an oriented east/west trough axis with some level of spin located at 23.5N & 93.5W. A new tower does appear to be popping over this point but I'm not yet convinced this to be a developing LLC or just an eventual eddy. What is also of interest, is an area along this axis around 23.5N and 89.5. This would appear to be a broader location of a potential MLC and where I could see conditions being better shielded from upper level shear further to it's west. I'm actually surprised that NHC doesn't have development odds closer to 50% for a TD or min. TS to develop and track somewhere between Tampa and Apalachicola.

[Dean4Storms]

Think they'll up the chances with this convection firing near the surface low.

[robbielyn]

We're getting heavy tropical downpours along the nature coast of Florida already this morning well removed from the disturbance. Looks like at a minimum its pulling up deep tropical moisture now. Current shear analysis does show only 5-10 kts in the central GOM with higher shear along the northern gulf cost and south of the disturbance. There my be a sweet spot opening up for some limited development. It is afterall, peak of the season.

Sweet spot indeed. During those years where the background state suggests a general overall favorability, I tend to not look at those areas where conditions are least favorable but more broadly view "how" and "where" development might occur in spite of those negative factors. Upper level shear is a factor however continued convective bursting generally can also help deflect the strong shear and help build somewhat of a more relaxed flow as well. I see 91L as an oriented east/west trough axis with some level of spin located at 23.5N & 93.5W. A new tower does appear to be popping over this point but I'm not yet convinced this to be a developing LLC or just an eventual eddy. What is also of interest, is an area along this axis around 23.5N and 89.5. This would appear to be a broader location of a potential MLC and where I could see conditions being better shielded from upper level shear further to it's west. I'm actually surprised that NHC doesn't have development odds closer to 50% for a TD or min. TS to develop and track somewhere between Tampa and Apalachicola.

Very interesting indeed at 23.5N 89.5W you can see a spin then convection over that area. We should definitely keep an eye on it.

[Dean4Storms]

Really believe the shear is helping fire off the convection and we've seen this song and dance before of enough shear to help set it off but also keep it in check once an LLC gets established.

[Sciencerocks]

[drezee]

 https://twitter.com/andretrotter/status/1435271497321381889

[Frank P]

Here is one LLC that looks looks like it is trying to form: 23.2n and 93.7w

https://i.ibb.co/4NnwvrB/AC516-E62-5995-4-BC9-8581-CDBE818-E0102.jpg

https://i.ibb.co/tbRLS9V/goes16-vis-91-L-202109071242.gif

Just watched shear absolutely destroy a tower trying to form and basically the entire LLC at this location.

[Nimbus]

Outflow boundaries for the westernmost low level eddy as Frank mentioned.
Inflow looked more persistent ~89-90 degrees where the shear is a little lower.
Could be a sloppy mess for Florida if it develops much more and 12Z GFS lends support.
NHC will probably up percentages since we don't have a certain center position yet.

[tropicwatch]

Most of the rotation we are seeing on satellite appears to be at the 700-500mb level.

http://tropic.ssec.wisc.edu/real-time/windmain.php?&basin=atlantic&sat=wg8&prod=vor3&zoom=&time=

[drezee]

 https://twitter.com/andretrotter/status/1435283019296743430

[xironman]

I am not sure the shear is that impressive.

[tropicwatch]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Tue Sep 7 2021

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

The National Hurricane Center is issuing advisories on Hurricane
Larry, located over the central Atlantic several hundred miles
southwest of Bermuda.

Showers and thunderstorms have increased today over the
south-central Gulf of Mexico in association with a surface trough
and an upper-level disturbance. The system is expected to move
slowly northeastward over the central and northeastern Gulf of
Mexico during the next couple of days. Upper-level winds are
currently unfavorable for development, but they are forecast to
become more conducive for some limited tropical or subtropical
cyclone development as the system nears the northern Gulf coast on
Wednesday and Wednesday night. The disturbance is then expected to
cross the southeastern United States, and some slight additional
development will be possible after it emerges off the southeastern
United States coast late this week. Regardless of development...
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...medium...40 percent.

$$
Forecaster Latto