Low Pressure Inland over the Southern U.S.

[NDG]

I was in argument with some young mets a couple of weeks ago during the San Francisco storm they were saying that the storm had tropical characteristics right before moving inland, I kept questioning how in the world it was to have it while tracking over SSTs in the low 50s, there was no way.
I think this system if it stays offshore long enough it may acquire some subtropical characteristics over SSTs in the 70s, which is warm enough for hybrid/subtropical systems with a "cold" atmosphere on top of it, is all relative speaking. IMO.
At least for south Louisiana, MS and AL get ready for a wet couple of days with the Euro, UKMET, GEM & ICON showing some high precip values while the GFS not so much.
BTW, if the Euro is correct it shows some wind gusts in the 30-50 mph range from the south shore of SE LA to coastal areas of the north central gulf coast starting tomorrow morning through Thursday morning, something to keep in mind.

[Dean4Storms]

I was in argument with some young mets a couple of weeks ago during the San Francisco storm they were saying that the storm had tropical characteristics right before moving inland, I kept questioning how in the world it was to have it while tracking over SSTs in the low 50s, there was no way.
I think this system if it stays offshore long enough it may acquire some subtropical characteristics over SSTs in the 70s, which is warm enough for hybrid/subtropical systems with a "cold" atmosphere on top of it, is all relative speaking. IMO.
At least for south Louisiana, MS and AL get ready for a wet couple of days with the Euro, UKMET, GEM & ICON showing some high precip values while the GFS not so much.
BTW, if the Euro is correct it shows some wind gusts in the 30-50 mph range from the south shore of SE LA to coastal areas of the north central gulf coast starting tomorrow morning through Thursday morning, something to keep in mind.

If it gets more time over the warm water or develops further southward it might get a shot but hardly see any models outside the NAM and a few Ensemble members here and there making much of it right now. Still think it bears watching, could surprise us.

[cycloneye]

Split the last two posts from the global models discussion thread to make a new thread for the area of low pressure in GOM. Model runs can be posted here.

[Steve]

Pressures are pretty high on the hour - 30.23 in Biloxi, 30.25 in Gulfport, 30.22 Houma, 30.25 Slidell, 30.23 New Orleans

Current observations in those cities show winds ENE around 9-12mph except Houma which is NE but also the farthest west of the 4 sites noted. NWS has the probabilities up for the chance of > 2" of rain.

[Nimbus]

There is a second cold front digging south fast down through Texas headed for the gulf.
Not sure which models have the best handle on the forecast.
The first cold front dug all the way south of Florida and the winds on the back side are from the northeast so that is probably the setup for a cutoff low wednesday or Thursday.

[cycloneye]

 https://twitter.com/weatherchannel/status/1645471414814638086

[Dean4Storms]

12z NAM with a 60mph Sub or pure Tropical ST into P'Cola. Winds gusting up close to 70mph. 12z GFS and ECM not as enthusiastic but the Low gradient putting out 40-50mph gusts out over the Gulf.

[AJC3]

12z NAM with a 60mph Sub or pure Tropical ST into P'Cola. Winds gusting up close to 70mph. 12z GFS and ECM not as enthusiastic but the Low gradient putting out 40-50mph gusts out over the Gulf.

Granted, the character of the cyclone won't make a difference when it comes to its impacts, but It is literally not subtropical, let alone tropical in the NAM. It's frontal. The NAM 2M temperature forecast at 78 hours shows a 12F temperature gradient across its center, and nearly 25F across its RMW.

This is 12Z "landfall".



This is the 18Z run....



Every single reliable global and mesoscale model shows clear warm and cold frontal features coming out of the low. The fact that the models are showing this to be a frontal cyclone, rather than subtropical (let alone tropical) couldn't be any more clear. As much I hate to beat a dead horse, I will. The environment this low spins up in will be strongly baroclinic all the way down to the surface, and under strong jet forcing. There won't be nearly enough time for this to shed it's frontal characteristics. Hypothetically, the most you'd get out of this would be frontal hybrid.

[Gums]

Salute!

Way it looks we FL Panhandle folks will get a fair rain on Thursday. Original forecast was Tuesday/Wednesday, but the new front is moving things east.

Way too early for tropical stuff, but I am willing to bet on a May disturbance in the Gulf.... any takers?

Gums sends...

[Steve]

AjC and Wx57 have the meteorology right. But it’s April, so it’s cool to watch. It’s almost like a heat surge is coming up with the system as it is isolated beneath low pressure but there’s a strong Atlantic high to the north of the system. And we know from enough past observations that you look south of a big ridge of eastern high pressure. It’s spring so it’s not going to act like a winter Gulf low or a summer or fall one either. Mesoscale models are the ones to watch with this system. Maybe radar products in a couple of days. NAM 12km likes more toward the MS/AL line.
FV3 high-res gets it to 997 and brings it north through SELA as it comes in. Caveat is that it’s April. And any lows in the tropics or subtropics in the basin are probably moving ENE or NE and much farther east than where this closes off. FV3 precip is still loading but it does indicate the shot at training to the east of the center. That’s not some 20”+, but you could see some 3-4” amounts pile up quickly. RGEM had a very slow evolution and loops the low South of Houma before getting it picked up by the next trough.

Air was different today. Breezy and cool. Mid level humidity and lots of variable clouds moving across from the E and ESE. Pressures still are in the 33.2x range which is overall on the higher side for New Orleans.

[LarryWx]

Salute!

Way it looks we FL Panhandle folks will get a fair rain on Thursday. Original forecast was Tuesday/Wednesday, but the new front is moving things east.

Way too early for tropical stuff, but I am willing to bet on a May disturbance in the Gulf.... any takers?

Gums sends...

Oncoming El Niños actually do on average have a somewhat higher chance for a May Gulf storm than other years fwiw.

[wxman57]

Just a frontal low, and not a very strong one.

[Nimbus]

The little dry vort near the Florida keys is at the tail end of the first trough.
I haven't been following the models since there is so much shear but this is the low the thread is following?

[Steve]

The little dry vort near the Florida keys is at the tail end of the first trough.
I haven't been following the models since there is so much shear but this is the low the thread is following?

I don't think it's that particular spin though it could be if it could migrate NW to off the LA coast by tomorrow. FVH3 looks to keep that spinning near South Florida as a low spins up in the Gulf. Not sure if it's already existing in some form or if it's not yet out there. There are intersecting clouds at different levels in the Gulf, but I don't see spin on visible near where the low should be tomorrow.

https://www.tropicaltidbits.com/analysi ... 41112&fh=6

[tropicwatch]

Kind of surprised to find 925mb vorticity in the central gulf this afternoon.

[SFLcane]

[Aric Dunn]

So far the system has been progressing right in line with the MESO models. could easily get an STS/TS briefly from this.

watch how far SW that upper low moves. MESO models want to bring it farther SW than globals allowing for the shear to decrease especially as it moves north. Relative shear will decrease to a doable level if that happens. Cooler air aloft and about upper 70s to around 80f ssts should give it a decent shot the next 36 hours or so.

MESO models are great with this kind of system and setup. dont think we are going to get anything like some of the MESO models are showing.... but.......

[Steve]

Agreed on about all that. STD (lol) looks like most it could ever get classified as. But it will be cool to watch the cyclone take shape tomorrow afternoon and evening. Seems like a marine type system as there are gale warnings and small craft advisories across the north Gulf. Otherwise coastal flooding as advertised by NWS, some rain for Plaquemines, Lafourche and Terrebonne and maybe to the east of the surface low because rain should coalesce on the eastern side tomorrow night into Thursday. So if you’re traveling between Slidell and Pensacola, be on the lookout for some brief heavy rain. Pressures are still relatively high.

[us89]

For what it's worth, multiple runs of the HRRR have organized and intensified this an actual fully tropical hurricane making landfall somewhere in the Mobile vicinity early Thursday morning. I'm not buying the 64 kt winds it spits out with a central pressure of only 998 mb, but definitely going to watch this closely. Could wind up with a rainband tornado/damaging wind threat here in Tallahassee tomorrow. Definitely agree with SPC's current marginal risk over us.

[cycloneye]

...SPECIAL FEATURE...

Gulf of Mexico Gale Warning: Strong to near-gale force E winds
with frequent gusts to gale-force are occurring across the
eastern gulf, mainly E of 88W. Seas range between 8 to 9 ft in
this area. Winds will be increasing to gale-force this afternoon
over the NE gulf waters as a low pressure center develops near
28N91W and moves N through tonight. Seas will peak to 11 ft with
the strongest winds. Once the low has moved inland, marine
conditions at both locations will improve by Thu afternoon.