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Severe WX April 11th-13th, 2020 Severe Weather Threat

MSUKentucky said:
First hope everybody is doing great and safe and have a Happy Easter. I'm a meteorology buff and always read this forum. Some of the brightest folks are literally on this very forum.
This will be a very interesting system in my opinion. Could be extreme, could be a Forecasted Convective Amplification Deficiency, but I personally think again imo you will see a more northern trend in terms of the tornadic threats. I've noticed lately models have been too farth south with the main threats. Also I feel more towards the actual low you will such much more instability than what models are showing. In my opinion I feel like Mid Central Tennessee will be the hotspot.
In present tense right now it's a craps game what is going to unfold for tommorow. But from what I see in terms of the models, historical aspects, etc I feel that's what's going to play out.
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Hello and welcome! I'm pretty new myself but I've loved learning by observation and from other members during my time here. :) What a time to have joined with this mess of weather!
 
MSUKentucky said:
Where you from?
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I'm in the Dallas-Fort Worth area, so I try to keep up with any Texas weather-related coverage.

Speaking of, cells are starting to pop up to the NW of the rogue Del Rio cell (which is dropping ping pong ball hail currently over Uvalde). It's bouncing back into a E-NE track from a SE track.
 
For what it's worth, even though CAMs are really not being particularly impressive in developing the warm sector, they're still painting such an extremely volatile parameter space that I wouldn't let down my guard at all. Anything that DOES develop, whatever the storm mode, could still drop significant tornadoes, even if it's just long enough to obliterate a mobile home, so could still be a dire day.

RAP northern MS

2020041200_RAP_021_33.2,-89.81_severe_ml.png

NAM 3K near Meridian

2020041200_NAMNST_022_33.04,-89.89_severe_ml.png
HRRR uh, right overhead me ahead of the cell the 00z develops near Fayette

hrrr_2020041200_022_33.8-87.29.png
 
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Equus said:
For what it's worth, even though CAMs are really not being particularly impressive, they're still painting such an extremely impressive parameter space that I wouldn't let down my guard at all. Anything that DOES develop, whatever the storm mode, could still drop significant tornadoes, even if it's just long enough to obliterate a mobile home, so could still be a dire day.

RAP northern MS

View attachment 2763

NAM 3K near Meridian

View attachment 2764
HRRR uh, right overhead me ahead of the cell the 00z develops near Fayette

(won't let me post it, hold on)
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Right...and the open space that the hrrr is showing in the mid afternoon is very concerning. The UH streaks are limited but the environment is highly gassed up.
 
CAMs can be extremely accurate but days like 5/20 show that they don't always have a perfect handle on sometimes subtle conditions that can make or break an event; the warm sector is going to be nerve-wracking until the final batch moves through regardless of what models show
 
OK. I'm trying to catch back up. The last I saw was at 9 PM CDT. At that point, Fox 6 in Bham showed the temp here at only 71 at 3, but the S 1/2 of the state close to 80. I would think that the warm front will have to haul for CEN AL to get into the warm sector in time to interact with the other ingredients. But things may have changed again.
 
Fort Rucker radar has been down for days so doubt its back tomorrow. Next closest one is Eglin 65 miles away. Will NWS warnings be less reliable? Id guess whats happening near the ground isn't as easy to tell being farther away?
 
00z HRRR certainly still shows the heart of the warm sector (picked Chilton county) to be worth monitoring, shows a loaded gun with impressive lapse rates and a weak enough cap that should eventually be easy to break with the usual slightly higher temps than modeled; NAM3k while also throwing PDS TOR soundings in the same area and a nasty shear profile (with dews at 70) shows weak lapse rates and a slightly stronger cap. Again though we really won't know until the event is upon us. Time to watch for the first signs of radar echoes I guess.

There are also models consistently showing backing or significant weakening at 700mb that could mess with storm mode. Still a lotta variables but the ceiling is still pretty high all things considered
 
Even the WRF-ARW and WRF-ARW2 seem to paint two very different scenarios. Usually they're in good agreement. I feel like this is unfortunately going to be a wait and see with the late hour CAM discrepancies. Unless we get a unified solution by morning there will remain decent uncertainty on the impacts but the potential is undeniably there. There's plenty of dangerous parameters but we don't have the comfort of consistency for mesoscale features which as we all know can make this a "few tornadoes" situation or a frequently referred-to devastating outbreak for years to come situation.

On another note I have some questions, I can recall countless systems like this (maybe not so classic and potent) Forecasted Convective Amplification Deficiency from junk convection, but I haven't seen a good explanation as to why that is a low probability outcome this time around. I understand air-mass recovery (such as the infamous three-rounds outbreak in April during you know what year) can be incredibly efficient and quick.. why is such excellent recovery expected from this system if junk convection works over the atmosphere during the afternoon? We don't have the same higher temps/dews that 4/27 had IIRC. Does the LLJ or rapid moisture advection have more to do with recovery than the thermal profile that's being pumped into the region? Is there a chance mid/late afternoon messy storm mode lingers and we get cell-interactions that inhibit discrete monster cell growth?
 
Equus said:
00z HRRR certainly still shows the heart of the warm sector (picked Chilton county) to be worth monitoring, shows a loaded gun with impressive lapse rates and a weak enough cap that should eventually be easy to break with the usual slightly higher temps than modeled; NAM3k while also throwing PDS TOR soundings in the same area and a nasty shear profile (with dews at 70) shows weak lapse rates and a slightly stronger cap. Again though we really won't know until the event is upon us. Time to watch for the first signs of radar echoes I guess.
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Where is the warm front? I assume that someone has the dewpoints info to help us find it.
 
Dews are hitting 60 along the Gulf Coast, so it's already surging inland; probably will be a few hours before we start seeing a really significant change here

Not gonna check it for QC but here's where observations on SPC mesoscale site are showing 50s and 60s dews right now
dploc.png
 
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Mesoscale Discussion 0343
NWS Storm Prediction Center Norman OK
1103 PM CDT Sat Apr 11 2020

Areas affected...portions of the Rio Grande Valley and Edwards
Plateau...into the Hill Country of Texas

Concerning...Tornado Watch 102...

Valid 120403Z - 120500Z

The severe weather threat for Tornado Watch 102 continues.

SUMMARY...Isolated severe/tornado risk continues.

DISCUSSION...A persistent, small supercell storm now over Uvalde
County in southern Texas continues moving eastward toward southern
portions of the Hill Country and possibly into the San Antonio area
around 1 AM. Risk for hail appears to be the main threat with this
storm, at this time.

This remains the only storm within the WW area, though weak cellular
development is occurring near and north of the portion of the river
between Terrell and Del Rio. Here, high-res CAM output continues to
suggest robust convective development over the next few hours.
Though much of this convection may spread northeastward across the
Concho Valley region toward northwestern Texas, a few of the storms
may affect western portions of WW 102.

mcd0343.gif
--

this cell has had 'that look' to it for a while and keeps trying but failing to drop anything. what could be inhibiting it from producing a tor?
 
Equus said:
Dews are hitting 60 along the Gulf Coast, so it's already surging inland; probably will be a few hours before we start seeing a really significant change here
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Got it! Demopolis is 49, but Bham is still just 39. There's a ton of advection needed by tomorrow afternoon for everything to come together. I don't think that it can happen, which would be a good thing.
 
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