ATL: OLGA - Post-Tropical - Discussion

[NDG]

[tolakram]

Yea, cold air coming fast.

https://rammb-slider.cira.colostate.edu/?sat=goes-16&z=3&im=12&ts=1&st=0&et=0&speed=130&motion=loop&map=1&lat=0&opacity%5B0%5D=1&hidden%5B0%5D=0&pause=0&slider=-1&hide_controls=0&mouse_draw=0&follow_feature=0&follow_hide=0&s=rammb-slider&sec=conus&p%5B0%5D=eumetsat_nighttime_microphysics&x=3301.7225341796875&y=5936.7734375

[NDG]

But the northern edge of the cold front is slowing down some, 97L may get upgraded after all before it fully merges with the cold front later on today or tonight before coming ashore.

[johngaltfla]

I can see this is going to be a bumpy flight today. Y'all take care and everyone stay safe. Hopefully this is IT for the Atlantic Season and CONUS.

[NDG]

Interesting that the Euro does not show it becoming extratropical until it makes landfall before sunrise tomorrow morning, but lets not forget how it messed up with Nestor.

[NDG]

The big difference between Nestor and 97L is that the shortwave trough moved much faster over Nestor and left it behind before making landfall. With 97L the UL trough axis is still well west over west central TX and moving slowly eastward. The cold front over the upper TX coast is slowing down so 97L may have at least another 12-16 hrs before the shallow cold front catches up to it over SE LA.

[NDG]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Fri Oct 25 2019

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

Satellite imagery indicates that the circulation of the low
pressure system over the western Gulf of Mexico is becoming
better defined, and that the associated shower and thunderstorm
activity continues to show signs of organization. It appears likely
that a short-lived tropical cyclone will form later today. However,
the system is forecast to merge with a cold front and become
post-tropical tonight over the northwestern Gulf of Mexico.
Regardless of development, gale-force winds are expected behind the
cold front over the western Gulf of Mexico today and Saturday. For
more information, see High Seas Forecasts issued by the National
Weather Service. An Air Force Reserve Hurricane Hunter aircraft is
scheduled to investigate the system later today, if necessary.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...70 percent.

[Aric Dunn]

I would be shocked if they upgrade. Should have been upgraded yesterday.. more likely we see yet another non-upgraded tc this year.

[NDG]

I think that once we get in some vis sat pics in they will upgrade it at 10 AM CDT.

[Aric Dunn]

Reminds me of wilma in a way. Very cold air right behind it. I remember driving to the nw side of wilma and all of a sudden the temp dropped 20 degrees right at the edge of the CDO. Winds still hurricane gusts. .. cold dry air just could not get pulled in due to its forward motion. And the boundary.

Not saying it wont get pulled with this system. Just interesting to see it so close on sat but moving somewhat perpendicular to the system

[Steve H.]

The system that is moving through the Midwest and East is a positively tilted one that doesn't have a lot of push like the one that was associated with Nestor. This front will not make it through the eastern half of the GOM and the Florida peninsula so it will not clear out those areas of heat and humidity. In fact, it will act to draw more moisture and rain into the southeast as the low heads NNE. No strong cold front for the foreseeable future.

[NDG]

The system that is moving through the Midwest and East is a positively tilted one that doesn't have a lot of push like the one that was associated with Nestor. This front will not make it through the eastern half of the GOM and the Florida peninsula so it will not clear out those areas of heat and humidity. In fact, it will act to draw more moisture and rain into the southeast as the low heads NNE. No strong cold front for the foreseeable future.

Yeah, the cold front's section north of 97L over the upper TX coast is already slowing down.

[Dean4Storms]

Looking more likely than not that the core of the center stays out in front of the cold front till near landfall in my opinion. Bet we see enhanced convection today.

[wxman57]

Looks like a west Gulf low along the cold front. Front extends south from the low. Not tropical.

[Steve]

Looks like a west Gulf low along the cold front. Front extends south from the low. Not tropical.

It does. But there looks to be some tropical processes as well at play here. Maybe semi-hybrid or something, but I think they'll classify it later today as a TD or possibly a lower end TS if Recon finds the right winds close enough to the surface. Looks like there is a mix of warm core, forcing and possibly even some phasing. Maybe it just appears that way because of the nearby environmental factors, particularly the push from the ESE/SE out in front of it helping to consolidate and concentrate the rain between the front and the high pressure to the E. It's been raining here off and on all night but it's coming down about as hard as it has so far. Processes are squeezing more rain out of this than I thought they would.

Edit - first reds through.
https://www.weather.gov/lix/

[NDG]

Buoy 42002 will see the LLC pass over it or very close to it, pressure down to 1007mb, winds gusting to 33 knots.

[NDG]

Looks like a west Gulf low along the cold front. Front extends south from the low. Not tropical.

Wxman57 va the NHC once again

Hope you’re enjoying our summer temps & humidity in Orlando this week

[GCANE]

Big issue with Nestor is that it was interacting with a PV Streamer.
Not the case this time.

[Steve]

Special Tropical Weather Outlook - TC is forming (Dr. Avila).
https://www.nhc.noaa.gov/text/refresh/M ... WOAT.shtml

[GCANE]

000
ABNT20 KNHC 251345
TWOAT

Special Tropical Weather Outlook
NWS National Hurricane Center Miami FL
945 AM EDT Fri Oct 25 2019

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

Special outlook issued to update discussion of systems in the Gulf
of Mexico and southwest of the Azores.

Updated: Visible satellite imagery and surface observations indicate
that a tropical cyclone is forming in the western Gulf of Mexico,
and advisories will be initiated on this system later this morning.
The system is forecast to merge with a cold front and become post-
tropical tonight over the northwestern Gulf of Mexico. Gale-force
winds are expected behind the cold front over the western Gulf of
Mexico today and Saturday. For more information, see High Seas
Forecasts issued by the National Weather Service. An Air Force
Reserve Hurricane Hunter aircraft is scheduled to investigate the
system later today.
* Formation chance through 48 hours...high...near 100 percent.
* Formation chance through 5 days...high...near 100 percent.

Updated: Recent satellite derived winds indicate that the small
non-tropical low centered a few hundred miles southwest of the
western Azores is producing tropical-storm-force winds near the
center. The thunderstorm activity is becoming better organized and
if this trend continues a tropical or subtropical cyclone could form
later today. The low is forecast to move toward the east-northeast
for the next day or so and interests in the Azores should monitor
the progress of this system. For more information, see High Seas
Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...medium...50 percent.

&&
High Seas Forecasts issued by the National Weather Service can be
found under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and
online at ocean.weather.gov/shtml/NFDHSFAT1.php

$$
Forecaster Avila