ATL: GAMMA - Post-Tropical - Discussion

[AutoPenalti]

Watch how the GEFS tracks have this putting on the brakes as they head towards Florida where they turn west away.

https://i.postimg.cc/WznHdPsv/gfs-ememb-lowlocs-watl-fh0-120.gif

Looking at the steering flow, it's ALMOST unrealistic at how it just turns west like that.

[aspen]

Levi’s video on 91L and the 0/30 AOI. It turns out the hard left turn on the GFS isn’t that unrealistic.
[youtube]https://youtu.be/Rw1XM3M_5fs[/youtube]

[tiger_deF]

Have to say I'm really impressed by the intensity of the trough that's been digging out in the Atlantic for almost a week now. Even for late fall/winter seeing something like this is somewhat unusual. I would expect to see some potentially anomalous tracks for these future systems

[Aric Dunn]

Very quickly organizing and low level structure is quite good.

[edu2703]

I bet it will be a TS when the first recon plane arrives.

[Michele B]

18Z GFS stronger and buries in the BOC. Odd pattern as the storm gets north of the Yucatan and still goes SW:

https://i.postimg.cc/59Y0Mk7r/gfs-mslp-pcpn-watl-fh6-150.gif

So the low moves sw yet most of its energy separates and heads north east? What’s the reason for that?

I just think it’s shear. Fla west coast prolly gonna get a lot of rain from this even if the low moves the other way.

Oh, great! MORE RAIN!!

We (think Peace River channel) are under Flood warning and expecting river flooding already - before this system formed! This thing coming at us will only add more rain.

It's certainly been a WET summer. I know....it's "rainy season..." but it's been unbelievably wet here. So glad we didn't have a tropical system drop even MORE rain.

[Aric Dunn]

and that should be our upgrade to TD at 5 am..

[CrazyC83]

and that should be our upgrade to TD at 5 am..

https://i.ibb.co/23SN2VP/asc-a-20201002-01-33-flag.png

Since it's close to land and warnings would be needed, they should just pull a Special Advisory out.

[Aric Dunn]

and that should be our upgrade to TD at 5 am..

https://i.ibb.co/23SN2VP/asc-a-20201002-01-33-flag.png

Since it's close to land and warnings would be needed, they should just pull a Special Advisory out.

I was thinking that. but its the middle of the night. not sure it would change much between now and 4 hours.

morning ASCAT will probably show a TS before recon even gets there.

[HurricaneAndre2008]

000
ABNT20 KNHC 020546
TWOAT

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Fri Oct 2 2020

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

Satellite imagery indicates that shower activity associated with
the broad low pressure are over the northwestern Caribbean Sea is
becoming better organized. Environmental conditions are expected
to be conducive for a tropical depression or a tropical storm to
form later today or Saturday if the system remains over the waters
of the northwestern Caribbean Sea or southern Gulf of Mexico.
Interests in the Yucatan Peninsula and northern Central America
should monitor the progress of this system as it moves generally
northwestward, as tropical storm watches or warning may be required
for portions of these areas later today or tonight. Regardless of
development, this system is expected to produce heavy rains, with
possible flash flooding, over portions of southeastern Mexico,
Central America, and western Cuba during the next several days. An
Air Force Reserve reconnaissance aircraft is scheduled to
investigate the system this afternoon, if necessary.
* Formation chance through 48 hours...high...80 percent.
* Formation chance through 5 days...high...80 percent.

$$
Forecaster Beven

[chaser1]

Well this escalated in a hurry. As if our Caribbean Tropical Wave had just been energized by Gamma Ray's or something

[GCANE]

TROPICAL CYCLONE FORMATION ALERT

[GCANE]

Anticyclone over the CoC with short-duration hot tower firing.
The Yucatan and Cold-Front creating massive TPW convergence.

[GCANE]

IR-Satellite analysis estimating 35-knt surface winds.

[GCANE]

Pressure dropping rapidly at the Yucatan Buoy

[Hammy]

Never trust a storm over the NW Caribbean in October, especially with that upper air setup. Might find a 50 mph system by the time the plane gets out there tomorrow at this rate.

[edu2703]

Satellite imagery indicates that shower activity associated with
the broad low pressure area over the northwestern Caribbean Sea
continues to become better organized. Environmental conditions are
expected to be conducive for a tropical depression or a tropical
storm to form later today or on Saturday if the system remains over
the waters of the northwestern Caribbean Sea or the southern Gulf
of Mexico. Interests in the Yucatan Peninsula and northern Central
America should monitor the progress of this system while it moves
generally northwestward, as tropical storm watches or warnings may
be required for portions of these areas later today or tonight.
Regardless of development, this system is expected to produce heavy
rains, with possible flash flooding, over portions of southeastern
Mexico, Central America, and western Cuba during the next several
days. An Air Force Reserve reconnaissance aircraft is scheduled to
investigate the system this afternoon, if necessary.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 5 days...high...90 percent.

[Tampa Bay Hurricane]

Huge moisture field- I see a favorable set up for predecessor rain event- surface blocking ridge East of 91L, trough developing over East Florida, another trough over central GOM, and moisture streaming up from 91L along stationary boundary lifting north over Florida.

The old front lifting north over the Florida Peninsula will met by 2.4”+ precipitable water values moving in from the SW and this convergence along the front forces ascent and leads to heavy rain developing in a large multicellular cluster that moves north over the peninsula with many training cells within.

Think we might get lots of rain- HWRF, GFS, and GFS Para send the center of 91L into the central gulf and then turn it west towards the western gulf; these models, especially the HWRF separate the Mid level circulation from the Low Level Circulation, due to strong shear that can be seen looking at the mid levels on the models. The Mid Level Circulation accelerates NE towards the Florida Peninsula, and that combined with the moisture and the front bring bands of heavy rain across Florida Sunday and Monday. The center tracks west and encounters more favorable conditions in the Western Gulf, potentially intensifying and threatening areas in the Western Gulf- potentially Texas, Mexico areas. Quite a bit of rain on the way for the Florida Peninsula, especially central and south. 3-4 inches with higher amounts localized. Parts of the SE Coast of FL have already seen a lot of Flooding from yesterday's deluge. Predecessor Rain Event Likely across Florida Peninsula.

[Emmett_Brown]

Better organized by the hour, over earth's highest heat content water, with an anticyclone right on top of it. Land interaction will be the only limiting factor for the next 72 hours. Could intensify quite a bit. HWRF and HMON showing cat 1 or so by the time it reaches the NE tip of the Yucatan.

[MGC]

First light visible sat images show a noticeable spin in 91Ls clouds. Sure looks like formation is close at hand. Break in activity is over......MGC