Severe Threats: Winter 2023-2024

[Chinook]

On Monday, 11/20, we will have our first tornado threat for the late fall/winter of 2023-2024. The SPC has a slight risk for 11/20, and a marginal for tomorrow (11/19). I expect a fairly high level of convection late in the day on 11/20, possibly around 00z. I'm sure weather forecasters will monitoring the weather much earlier than 00z. 500mb winds will be about 65 knots in Louisiana.

[Chinook]

SPC update today, at 1730z, with 10% hatched for tornadoes and 30% for a small area for severe winds, 15% for hail.

 

[CheeselandSkies]

00Z WRF-ARW would be...problematic, to say the least across LA/MS. Consistent with its previous (12Z) run. HRRR looks pretty rough too, has uptrended somewhat from earlier runs.

[Ed, snow and hurricane fan]

Suggestion in SWODY 1 of a possible Moderate later today.

[Wmsptwx]

2 hours ago, Ed, snow and hurricane fan said:

Suggestion in SWODY 1 of a possible Moderate later today.

No upgrade at 1630z

[Ed, snow and hurricane fan]

It is starting.

 

https://radar.weather.gov/station/KPOE/standard

[nwohweather]

It's been a pretty quiet second severe season compared to the last few years (looking at you 2021). If a supercell can avoid all the crowding later this afternoon there's definitely the threat of a strong tornado. Some solid ingredients in play across LA

[Chinook]

these are, I believe, the confirmed tornadoes today

[nwohweather]

these are, I believe, the confirmed tornadoes today

Definitely had that great Dixie Alley hook to it, but as usual overcrowding of storms put a lid on things

[Chinook]

SPC has a day-3 outlook, that is now valid for just 48 hours in the future on Thursday night. There should be a good amount of convection down around Houston on Thursday. I don't know if this will be much more than a slight risk.

[Ed, snow and hurricane fan]

Enhanced risk N part of HGX CWA, my house on the edge of Enhanced, Houston and S is Slight.  Looking at 3k NAM and FV3, I don't think the 10% tornado probability area will verify.  Shear and vorticity are there, instability is not that exciting.  Maybe some cold season brief EF-0 and EF-1s.  I guess we'll see if the Enhanced is still there at the mid day update.

[Chinook]

10 hours ago, Ed, snow and hurricane fan said:

Enhanced risk N part of HGX CWA, my house on the edge of Enhanced, Houston and S is Slight.  Looking at 3k NAM and FV3, I don't think the 10% tornado probability area will verify.  Shear and vorticity are there, instability is not that exciting.  Maybe some cold season brief EF-0 and EF-1s.  I guess we'll see if the Enhanced is still there at the mid day update.

The models forecast many storms tomorrow. I like to see this, as I think it correlates with many storm reports in the real world. On the other hand, there could be many interfering storms and few tornadoes tomorrow. That's a possibility.

[Stx_Thunder]

Looks like one of those very shear-dependent setups (rather than thermodynamic). Which is pretty typical this time of year. Especially with all these cold frontal intrusions of late all the way into the western/southern Gulf.

I read in the earlier day 2 SPC discussion from today that they were thinking of downgrading the risk (I can see the valid reasoning why in their discussion details especially about the forecast rapid warming profile aloft from 850mb - 500mb layer). Though it's a bit surprising they even mentioned a possible downgrade especially for those typical areas of concern (Houston and eastward), only being around the Gulf coast during the cold season.

0Z Brownsville or BRO sounding this evening showing that there's already about 200 MUCAPE around 700mb, and 1.8 PW (versus 1.3 on this morning's 12Z) down there. So they're right that it's a pretty rapid airmass modification pattern ongoing today in the WAA regime with 40 kt veering southerly LLJ here on the western side of the Gulf ahead of that next shortwave out west.

[Chinook]

the 12km NAM has just ripping 0-3km SRH values like a hurricane

[Chinook]

for what it's worth- some convection allowing models bring some distinctive updraft helicity tracks to the region

[Stx_Thunder]

Evidently looks like a pretty potent incoming shortwave into TX tomorrow. Even with very limited MUCAPE (although elevated mid-level LRs near 7) this evening, already got occasional CG lightning discharges going on at times in the activity/impulse moving NE through the Brownsville/lower TX coast area. Thought I heard one rumble up here too about an hour ago.