ATL: ANDREA - Post-Tropical - Discussion

[cycloneye]

Still has a minimal chance today.

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Mon Jun 23 2025

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

Central Subtropical Atlantic (AL90):
Satellite images indicate that disorganized showers and
thunderstorms are displaced to the east of an area of low pressure
located about 600 miles east of Bermuda. Environmental conditions
are still marginally favorable for further development, and an
increase in thunderstorm activity could result in the formation of a
short-lived tropical depression today. By Tuesday, this system is
expected to encounter less favorable environmental conditions,
ending its opportunity for development. The system is forecast to
move northeastward around 10 mph, remaining over the open central
Atlantic.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 7 days...high...70 percent.

$$
Forecaster Hagen

[LarryWx]

Joe Bastardi calls these types of borderline systems outside of the tropics “ham sandwiches”. I have no idea why. Last year there were few unlike two years ago.

I've heard phrases like 'even a ham sandwich can win that election'. It is outside the tropics and it will use the name and 40 years ago Neil Frank was not in favor of naming storms forming out of the tropics that would affect nobody but shipping. They've been naming systems like this for at least 30 years. It looks pretty good, it might make a run at a name before its gets to colder water and higher shear.

It has been demoted to “turkey sandwich”.

[Sciencerocks]

I've seen worse depressions and minimum tropical storms. This is a very well defined LLC. Probably is enough but as they say it is no threat to land!

[Sciencerocks]

 https://x.com/hurricane_chase/status/1937169878873423994

[BobHarlem]

I'd watch the best track ftp for td1, but doubt it'll get a name. Shear is taking its toll.

[wxman57]

Appears to be merging with a front and getting sheared apart now. Good. Don't need any short-lived name. I only went 13/6/3 in the office hurricane contest.

[MGC]

Might have been a TD earlier but shear is tearing it. No need to classify it now......MGC

[cycloneye]

TS winds but is too late.

AL, 90, 2025062318, , BEST, 0, 339N, 540W, 35, 1014, LO

[johngaltfla]

Appears to be merging with a front and getting sheared apart now. Good. Don't need any short-lived name. I only went 13/6/3 in the office hurricane contest.

I can dig it.

But if a NHC staffer has 22/11/4 you know it's getting a name.

[Dean_175]

I don’t see this one becoming Andrea. It is looking pretty bare and withered now on satellite and the front is dominating. Dry air from the extratropics isn’t helping either. There is more of that now than last night. I can see them giving an unnamed storm designation in post-operational analysis though. Possibly out of a desire for consistency between advisories, NHC still has this as 60 percent (lowered from 70) and says it would need to gain organization and convection tonight or this afternoon before conditions become more unfavorable tomorrow. This would require that the current trend of decreasing convection and upper level clouds to quickly reverse. I am just not seeing that to be likely.

[wxman57]

Appears to be merging with a front and getting sheared apart now. Good. Don't need any short-lived name. I only went 13/6/3 in the office hurricane contest.

I can dig it.

But if a NHC staffer has 22/11/4 you know it's getting a name.

You may have a point there. However, they just dropped chances to 60%.

[Sciencerocks]

Well, we just got our first candidate for post season. Normally we have 2 or 3 of these by this point in many seasons of the past 20 years.

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Mon Jun 23 2025

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

Central Subtropical Atlantic (AL90):
Showers and thunderstorms have diminished this afternoon in
association with a low-pressure system located a little over 650
miles east-northeast of Bermuda. Environmental conditions are
marginally favorable for further development, and a resurgence in
thunderstorm activity could result in the formation of a short-lived
tropical depression or tropical storm this evening. By Tuesday, the
low is expected to encounter increasingly unfavorable environmental
conditions, ending its opportunity for development. The system is
forecast to move northeastward around 15 to 20 mph while remaining
over the open central Atlantic. For additional information,
including gale warnings, please see High Seas Forecasts issued by
the National Weather Service.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...medium...40 percent.

[DorkyMcDorkface]

The hurricane models show 90L regaining convection tomorrow morning to the point where it looks potentially classifiable. Could be its last shot at becoming a storm.

[StormWeather]

The hurricane models show 90L regaining convection tomorrow morning to the point where it looks potentially classifiable. Could be its last shot at becoming a storm.

https://i.imgur.com/STAVBeM.png
https://i.imgur.com/DvCLwI3.png
https://i.imgur.com/M6JcWOr.png

If I understand subtropical storms correctly and troughs correctly, a TC can spin up inside of a trough like Tropical Storm Patty did last November. Maybe that’s why the hurricane models are showing a brief surgance of convection tomorrow morning.

[cycloneye]

No convection left.

[cycloneye]

A small burst but well removed from the circulation.

[LarryWx]

It is still hanging in there for a chance to become a TC:

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 AM EDT Tue Jun 24 2025

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

1. Central Subtropical Atlantic (AL90):
A small area of disorganized showers and thunderstorms have
redeveloped on the north side of a gale-force low-pressure system
located about 700 miles east-northeast of Bermuda. Environmental
conditions are marginally favorable, and further resurgence of the
thunderstorm activity could still result in the formation of a
short-lived tropical depression or tropical storm. By later today,
the low is expected to encounter more hostile environmental
conditions, ending its opportunity for development. The system is
forecast to move northeastward at around 15 to 20 mph while
remaining over the open central Atlantic. For additional
information, including gale warnings, please see High Seas Forecasts
issued by the National Weather Service.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...medium...40 percent.

[cycloneye]

Keeps alive.

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Tue Jun 24 2025

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

1. Central Subtropical Atlantic (AL90):
Showers and thunderstorms have persisted with a gale-force
low-pressure system located about 900 miles east-northeast of
Bermuda. Environmental conditions are marginally favorable, and
further resurgence of the thunderstorm activity could still result
in the formation of a short-lived tropical depression or tropical
storm this morning. By later this evening, the low is expected to
encounter more hostile environmental conditions, ending its
opportunity for development. The system is forecast to move
northeastward at around 15 to 20 mph while remaining over the open
central Atlantic. For additional information, including gale
warnings, please see High Seas Forecasts issued by the National
Weather Service.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 7 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 Hagen

[ChrisH-UK]

90L still has a lower level circulation and has convection covering half of it but unlikely to become more due to cold waters that it is moving into.