ATL: Ex INVEST 90L - Discussion

[zzh]

 https://twitter.com/AndyHazelton/status/1528744401987637249

[Sciencerocks]

https://twitter.com/AndyHazelton/status/1528744401987637249

There's tons of storms that have popped up into even hurricanes within a day that would make such really foolish to have. One example is Hermine 2010 another is Humberto 2007. There's plenty of systems that go from literally nothing to named system within 6-12 hours like Bret and Gert 2005, Imeda on the texas coast a few years ago and so much more.

If this is is found to be deserving I don't see time being the limiting factor.

[InfernoFlameCat]

I don’t see time as a limiting factor either. The only limit I know of is the one minute sustained wind speed measurement. So if a system is a closed surface low with a warm core, and has sustained tropical storm force winds for only a minute ten meters above the surface, it was a tropical storm at that time. [This is of a general storm, not specifically Invest 90L]

[InfernoFlameCat]

On the bright side, maybe this is how we get our preseason streak to continue and still have a unique storm with the name of Alex!

[zzh]

Can someone explain to me why this is not a tropical cyclone?

Didn’t sustain deep convection over the center for long enough. One of the criteria for classification as a TC is sustaining said deep convection over the LLC for ~12 hours. Except for a brief period yesterday evening, this was a naked swirl. NHC made the right call imo.

I don't see that criteria neither on NHC's website nor on WMO's website. Can you share the source where you find that criteria for TC classification?

[stormhunter7]

Take a look at the WeatherSTEM station at Perdido key, Florida. The landfall was just after midnight and lowest pressure was 29.865/1011mb. Do a graph for 24 hours... looks pretty remarkable too with winds right at 35-40mph, and the center surface low coming ashore. Saw some wind gusts to the east near the 50mph mark.

https://escambia.weatherstem.com/data?refer=/fswnperdidokey

[AJC3]

Persistent central convection is a subjective operational criterion that's not in the AMS glossary. You'll see it mentioned in dozens of NHC's initial TCDs for TCs, and often times it'll be mentioned as a limiting factor in their TWOs.

[Ivanhater]

This may have been what the GFS was hinting at all along

[InfernoFlameCat]

This system reminds me of mindy from 2021.

[ScottNAtlanta]

This sure seemed like a decaying TS when it came through Atlanta this morning. Knocked out power and there was a wind shift when it passed.

[stormhunter7]

Pretty neat data on 90L coming ashore.

Check out the temperature spike to 77.9F from 70F when center came ashore! The dwpt also climbed too! Looks like wind in the center was around 13mph for about 20-30 minutes! check out both "walls" of the low at center, you can see the spikes as they pass over.


post pictures

https://escambia.weatherstem.com/data?r ... perdidokey

[NXStumpy_Robothing]

Been awhile since I've checked in on here (though I'm catching up in time to bust majorly with my predictions again), but I was linked this thread by a fellow enthusiast and noticed it wasn't linked here already. In my opinion, the data found here, if verified, could be crucial in post-season classification/designation for this system. Regardless, another fascinating borderline case of TC status we so often encounter early in the season.

 https://twitter.com/MichaelSpag/status/1528756815466487808

[Hurricaneman]

Been awhile since I've checked in on here (though I'm catching up in time to bust majorly with my predictions again), but I was linked this thread by a fellow enthusiast and noticed it wasn't linked here already. In my opinion, the data found here, if verified, could be crucial in post-season classification/designation for this system. Regardless, another fascinating borderline case of TC status we so often encounter early in the season.

https://twitter.com/MichaelSpag/status/1528756815466487808

Based on this tweet this was a tropical storm, do they upgrade it post season or leave it be

[Hammy]

Radar around time of landfall

[kevin]

I didn't think that much of it at the time, but reading back the posts now and seeing the radar + measurements I think there's a pretty good chance that this briefly was a TC. Will be interesting stuff for the post-season analysis.