Severe WX Severe Weather Threat - February 15-16, 2023

[Casuarina Head]

I haven't been paying super close attention since I went to sleep and then work, but it doesn't seem like anything too bad has happened overnight. No long-lasting, clear TDSs (although most of the tornado-warned storms have been in horrible radar holes) and no reports of major damage that I know of.

However, you are right, the HRRR is very ominous (surprisingly so, to me) for Alabama and portions of neighboring states this afternoon and has been consistent with that over quite a few runs now. Again at risk of hyperbole, but some of the simulated reflectivity looks disturbingly like a "4/27 lite."

At this point I am still skeptical that a MDT Risk will verify tornado-wise, much less “4/27 lite.” I think there will be an isolated supercell that produces an intense tornado or two, but multiple long-lived, intense tornado families seem rather unlikely at this time. The major threat appears to be localised and based on the mesoscale rather than synoptic scale. The aerial coverage of discrete activity also looks to be rather limited. People should definitely be prepared, but I still think that this event will not reach its “ceiling,” especially compared to projections* that were issued several days ago.

*Modelled, not SPC

 

[UK_EF4]

HRRR does continue to produce multiple discrete tornadic supercells... WRF NSSL and WRF ARW produce something similar yet not full model agreement among other CAMS. The parameter space continues to look favourable, though maybe not quite as much shear as notorious past Dixie setups - though that shouldn't be too much of an issue. I reckon SPC may upgrade to moderate eventually (maybe the 1630z outlook), but we will see. I said a couple of days ago I didn't see much potential for today but I fully take that back and admit I was wrong - a couple EF2-EF3 tornadoes do definitely seem possible today.

 

[UncleJuJu98]

At this point I am still skeptical that a MDT Risk will verify tornado-wise, much less “4/27 lite.” I think there will be an isolated supercell that produces an intense tornado or two, but multiple long-lived, intense tornado families seem rather unlikely at this time. The major threat appears to be localised and based on the mesoscale rather than synoptic scale. The aerial coverage of discrete activity also looks to be rather limited. People should definitely be prepared, but I still think that this event will not reach its “ceiling,” especially compared to projections* that were issued several days ago.

*Modelled, not SPC

Good grief dood

 

[Edith]

Good grief dood

Yeah I wonder if he really believes the nonsense he posts.

 

[CheeselandSkies]

Ok, how about "3/25/21" lite"? I should do a better job of always remembering 4/27/2011 was so exceptional it's really not valid as a comparison to any other event, even other high risk days.

 

[CheeselandSkies]

Yeah I wonder if he really believes the nonsense he posts.

I think in this case he's not too far off the mark, but if HRRR verifies, it could be pretty close to something higher-end.

 

[UncleJuJu98]

Can we just focus on the mesoscale details of the day today, today has the potential to bring loss of life to communities hit by a tornado if a tornado hits your area. It's your April 27th. In my books if a tornado takes a life than the ceiling has been met on a events unfortunately.

 

[Richardjacks]

the hrrr simlated ir is quite concerning, it shows plenty of sun breaking ot today over Alabama, by mid afternoon, some clouds in the sw ne orientation with a stout midlevel cap which dramatically weakens around 2/3 pm in western/central AL

 

[kcyalater]

let’s not derail the thread pls. lots to watch today and hopefully this DOESN’T verify, but i’d be lying if i said i’m not really concerned.

 

[Richardjacks]

gwx already showing one convergence zone this morning

 

[UncleJuJu98]

Some very strong southerly winds in Homewood right now. Here's the surface observations currently

 

[Lake Martin EF4]

Some very strong southerly winds in Homewood right now. Here's the surface observations currently View attachment 17899

What are the red and green numbers?

 

[UK_EF4]

What are the red and green numbers?

Temps and dew points

 

[Casuarina Head]

Can we just focus on the mesoscale details of the day today, today has the potential to bring loss of life to communities hit by a tornado if a tornado hits your area. It's your April 27th. In my books if a tornado takes a life than the ceiling has been met on a events unfortunately.

No one is saying that people should not be prepared. However, there are scientific criteria that must be met for an event to qualify as an outbreak, meet the MDT category, etc. For future reference these details are important. The problem is that there is a lack of perspective. Due to politicisation and climate-change hysteria even minor events are now being used as “proof” that climate change is causing much more severe events. As @CheeselandSkies mentioned, currently there is little reason to believe that we will see multiple intense tornado families, as opposed to just one.

 

[KevinH]

That I 59 corridor has a ton of supercells riding it, I mean good golly View attachment 17892View attachment 17893View attachment 17894

Why are all of your pictures cut off? I can’t see what hour they are valid for

 

[UK_EF4]

Comparisons can be made to the storm mode and distribution of storms on 4/27 without actually saying there will be a repeat. Yes some of the HRRR runs resemble the radar on 4/27. No the parameters are no where near as favourable and we will not be getting multiple EF4/EF5 tornadoes, no one is saying that is what’s going to happen either.

 

[Jpgood97]

This whole system is just weird. It’s been back and forth for the last 4 days. The helicity map showed swaths in TN and central AL, but skips over all of north AL. There’s no precip this morning in North AL, and there wasn’t clarification if it would or wouldn’t rain. Much less if that rain would help stabilize the atmosphere or destabilize with boundaries. Just a weird system imo, have to take it seriously though since there is little consensus.


Sent from my iPhone using Tapatalk

 

[Casuarina Head]

Just a few days ago we were seeing comments such as these:

That’s bout way I see it too. Maybe not quite far north as that . But expect both day 5 and day 6 have a 30 prob area . This is setting up to be first high risk day in awhile that’s if things hold on.

This was exactly my thoughts. I think the risk area will be quite large and possibly underestimated. There could be quite a large area that gets rocked by this storm system.

Very reminiscent in scope of March 2nd 2012. Keeps popping in my mind. Not in terms of magnitude but risk area. But I'm not sure that the highest risk would be in the Kentucky area like March 2nd. I'd say just off how I see it probably Tennessee Alabama and Mississippi

People were talking about a possible High Risk and/or a repeat of 2 Mar 2012 in terms of aerial scope, based solely on modelling. Obviously not even close...

This will still be locally significant, but certainly the ceiling is far lower than it was depicted several days ago. An isolated EF2+ or two ≠ a widespread outbreak.

 

[xJownage]

Comparing any event to 4/27 is just wrong, because the amount of things that have to swing a certain way in both the synoptic and mesoscale setup is absolutely insane to get an outbreak of that caliber. There's a reason we've only ever observed two outbreaks of that caliber. Event comparison with regards to synoptic setup is very useful for pattern recognition purposes, but our lack of understanding of weather on a large scale, and how that translates to output of very fickle phenomena like tornadoes, means you can't have expected similarities in output. It's just too hard to predict.

Last night: trough ejection was a bit late, which led to a lack of large scale ascent and overall weaker forcing for the eastern target. This meant that the 700mb temperatures remained even higher and the warm nose ended up preventing initiation, killing off storms because there wasn't enough localized forcing to break the warm nose. For context a warm nose =/= a cap, it's not an inversion - however the temperatures being so close together in that parcel (not fast cooling) meant that lapse rates were really low, too low to sustain surface based convection as parcels struggling significantly to punch through that layer.

Today: the consequence by last night's bust are two uptrends for today. The slower progression of the trough means that 1, the warm sector is bigger, and 2, the further westerly placement of the low has backed SFC winds in the warm sector quite a bit more. A contrasting downtrend is that the lack of robust convection in the warm sector this morning is going to prevent more outflow boundaries from being left, however, the overall backing of the SFC winds should more than make up for the difference.

I'm right there with Richard. Western AL in particular looks to be under the gun. SFC winds veer closer to the front, so we can hope the cap holds off prefrontals farther out and the storms we do get are closer to the veered SFC winds, which would neuter the higher-end threat.

 

[Clancy]

FFC keeping an eye on model and mesoscale trends. Instability looks to be low but there will be a corridor of marginal instability over about the western third of Georgia or so this evening, which, considering the wind fields, could result in an isolated tornado threat. Any uptrend in those parameters could be problematic. For those in Alabama and Mississippi, wishing y'all a quiet and safe Thursday.

.SHORT TERM...
(Today through Friday)
Issued at 412 AM EST Thu Feb 16 2023

Main forecast concerns in the short term period are likelihood and
timing of strong to severe convection and threat for heavy rain and
flooding.

Still uncertainty on how strong convection will be and arrival
timing. CAMs showing CAPE decreasing on arrival, likely due to
slower timing of line of convection. Upstream over MS valley states,
not seeing any formation of organized line of convection or feature
that often goes awry from model guidance. Thus, dont have any
evidence at this time that forecast timing would be too slow. Have
adjusted PoP grids to show convection moving in after 00Z. With
lower CAPE, likely less than 250 J/kg, will be difficult to get
widespread severe storms. If low level moisture to the SW of the
area trends higher than forecast, then will def need to reevaluate
forecast. Monitoring of observed trends will be key to best forecast
tonight. As it stands, given expected CAPE, strong vertical wind
shear, and HREF members showing Updraft Helicity tracks, could see a
few storms produce damaging winds with a brief tornado possible
between 7 PM and 3 AM tonight.