ATL: FERNAND - Post-Tropical - Discussion

[wxman57]

Looks terrible on satellite and it's heading for a higher shear area. Not sure what the NHC is looking at.

[CrazyC83]

It's possible that the shear being spun off Erin is playing a role? After all, Erin, even as a extratropical cyclone, is dominating the western Atlantic.

[cycloneye]

Southwestern Atlantic (AL90):
Showers and thunderstorms have not become any better organized this
evening in association with a trough of low pressure located a
couple hundred miles northeast of the northern Leeward Islands.
Environmental conditions appear conducive for further development of
this system, and a tropical storm is very likely to form this
weekend while it moves northwestward and then northward over the
southwestern Atlantic. Interests in Bermuda should monitor the
progress of this system as watches or warnings could be required on
Saturday. For additional information, including gale warnings,
please see High Seas Forecasts issued by the National Weather
Service.
* Formation chance through 48 hours...high...80 percent.
* Formation chance through 7 days...high...90 percent.

[HurricaneAndre2008]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Sat Aug 23 2025

Southwestern Atlantic (AL90):
Satellite images indicate that an area of low pressure has formed
about 500 miles south-southeast of Bermuda, and the associated
showers and thunderstorms continue to show signs of organization. A
tropical depression is expected to form later today or tonight, with
further intensification to a tropical storm likely on Sunday while
the low moves northward over the southwestern Atlantic. An Air
Force Reconnaissance aircraft is scheduled to investigate the low
this afternoon. Interests in Bermuda should monitor the progress of
this system as watches could be still required later today. For
additional information, including gale warnings, please see High
Seas Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...high...near 100 percent.
* Formation chance through 7 days...high...near 100 percent.

[Buck]

[MEANINGLESS_NUMBERS]

I still don’t understand why they don’t use the PTC designation and get those TS Watches out.

[HurricaneAndre2008]

[StormWeather]

https://knmi-scatterometer-website-prd.s3-eu-west-1.amazonaws.com/ascat_b_osi_co_prod/products/20250823_12_36_flag_det.png

Where’s the circulation? And why did they go 100/100 for this?

[Hurricaneman]

https://knmi-scatterometer-website-prd.s3-eu-west-1.amazonaws.com/ascat_b_osi_co_prod/products/20250823_12_36_flag_det.png

Where’s the circulation? And why did they go 100/100 for this?

Scatterometer missed the center, it’s under the convection

[StormWeather]

https://knmi-scatterometer-website-prd.s3-eu-west-1.amazonaws.com/ascat_b_osi_co_prod/products/20250823_12_36_flag_det.png

Where’s the circulation? And why did they go 100/100 for this?

Scatterometer missed the center, it’s under the convection

So if they went 100-100 at 8 am, the circulation is under the convection, should we expect a TD at 11?

[LarryWx]

Where’s the circulation? And why did they go 100/100 for this?

Scatterometer missed the center, it’s under the convection

So if they went 100-100 at 8 am, the circulation is under the convection, should we expect a TD at 11?

This is the 1st time I can recall them going 100% and them not designating it a TC at the next 6 hourly normal issuance time!

TWD:

Based on 0600 UTC surface analysis and satellite imagery through
0800 UTC.

...SPECIAL FEATURES...

Southwestern Atlantic (AL90):
Showers and thunderstorms from 22.5N to 28N between 59W and 64W
have become a little better organized in association with a trough
of low pressure, AL90, located a few hundred nautical miles north
of the northern Leeward Islands. Fresh to strong winds and seas to
around 8 ft are seen near this feature. Environmental conditions
appear conducive for further development of this system, and a
tropical storm is expected to form this weekend while it moves
north- northwestward and then northward over the southwestern
Atlantic. There is a high chance of formation within the next 48
hours. Please read the latest Tropical Weather Outlook for more
information regarding AL90 at website:
https://www.nhc.noaa.gov/cyclones/?atl for more details.

[FrontRunner]

So if they went 100-100 at 8 am, the circulation is under the convection, should we expect a TD at 11?

This is the 1st time I can recall them going 100% and them not designating it a TC at the next 6 hourly normal issuance time!

That's my recollection as well. Maybe they're holding off to wait for recon to confirm later today?

[LarryWx]

So if they went 100-100 at 8 am, the circulation is under the convection, should we expect a TD at 11?

This is the 1st time I can recall them going 100% and them not designating it a TC at the next 6 hourly normal issuance time!

That's my recollection as well. Maybe they're holding off to wait for recon to confirm later today?

If so, why not keep at 90%?

[StormWeather]

35 kts as of 12Z. I think it’s safe to say that should recon find a well-defined center, that we will likely get Tropical Storm Fernand later today.

AL, 90, 2025082312, , BEST, 0, 251N, 622W, 35, 1011, LO, 34, NEQ, 0, 90, 0, 0

https://ftp.nhc.noaa.gov/atcf/btk/bal902025.dat

[Sciencerocks]

[cycloneye]

Southwestern Atlantic (AL90):
Satellite images and Air Force Reserve aircraft reconnaissance data
indicate that an area of low pressure about 400 miles south-
southeast of Bermuda continues to get better-defined, and recent
satellite-derived winds indicate that the low pressure area has
gale-force winds east of the center. This system is expected to
become a tropical storm this afternoon or evening, with further
intensification likely through Sunday while the low moves northward
at 10 to 15 mph over the southwestern Atlantic. Interests in
Bermuda should monitor the progress of this system, though the
threat to that island appears to be less than yesterday. For
additional information, including gale warnings, please see High
Seas Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...high...near 100 percent.
* Formation chance through 7 days...high...near 100 percent.

[Sciencerocks]

Very strong MLC with signs of an LLC developing. Could take another 6-12 hours to completely work its way to the surface but once it does so this should be a tropical storm.

[tolakram]

This is the 1st time I can recall them going 100% and them not designating it a TC at the next 6 hourly normal issuance time!

That's my recollection as well. Maybe they're holding off to wait for recon to confirm later today?

If so, why not keep at 90%?

What does 90% mean, what does near 100% mean? If it ends up developing in the next 2 days then near 100% over the next 2 and 7 days is correct. In my opinion the NHC is saying that they are very confident we will have a storm in 2 to 7 days.

[zzzh]

AL, 06, 2025082318, , BEST, 0, 266N, 617W, 35, 1010, TS, 34, NEQ, 0, 90, 0, 0, 1015, 110, 90, 0, 0, L, 0, , 0, 0, FERNAND, S, 0, , 0, 0, 0, 0, genesis-num, 019, TRANSITIONED, alB02025 to al062025,

[StormWeather]

AL, 06, 2025082318, , BEST, 0, 266N, 617W, 35, 1010, TS, 34, NEQ, 0, 90, 0, 0, 1015, 110, 90, 0, 0, L, 0, , 0, 0, FERNAND, S, 0, , 0, 0, 0, 0, genesis-num, 019, TRANSITIONED, alB02025 to al062025,

I was getting ready to say. Watching recon, they found a well-defined center with 35-40 kt winds off to the east of the center.