Severe WX Severe Weather Threat 3/14-3/16

[Kds86z]

Just some thoughts from a weather enthusiast across the Atlantic... but I have really become extremely concerned about tonight across Northern Arkansas, and especially Southern/Eastern Missouri into Southern Illinois tonight, as trends have really increased confidence in a significant tornado outbreak. Wouldn't mind betting we see a High-Risk caliber event overnight - have really got a terrible feeling having looked at some of the latest model and observation data.

Confidence has massively increased that a tongue of quality moisture will now extent all the way up to C IL by around ~03z, and given the strength of the low level jet and steep lapse rates in the mid levels this is yielding a highly favorable environment for intense tornadoes - just take a look at the STP trend on the RAP.

More so, the compact upper low will be ejecting just to the north and west of this moist tongue. I added the rough extent of the 60F dps in the context of the 300mb chart so you can get a better idea of how they interact. This kind of look, where you have the tip of a speed max just impinging along an axis of instability, is a really really concerning look, reminiscent of a lot of classic tornado outbreaks. The forcing will be strong, but not extreme as it would be just a couple hundred miles to the north in which the upscale growth is largely favored. Your shear vectors are perpendicular enough for discrete supercells.

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Latest CAMS have now honed in on supercells developing along the pacific front/wind shift and maturing as we get the moisture return "just in time". When using CAMS (and In recommend viewing sim reflectivity the very last in your forecast!) you have to think - does this make sense and align with what you expect from the synoptic and environment? And in this case the answer is very much yes. The upper pattern as stated above really supports semi-discrete supercells, and you can easily expected broad showery convection in the very strong warm air advection that will be ongoing overnight. This will likely mature into intense supercells as models show. I can't say I fully buy the line of discretes all the way down to LA/ southern MS, but from N AR into IL these seem well modelled.

Forecast soundings I'm picking ahead of these cells show environments easily favorable of EF3-4+, violent tornadoes. Sure, the boundary layer is slightly dry, but you have a very solid instability profile, especially in the upper levels, and extreme SR inflow will likely be able to balance the downdrafts. That hodograph is extremely well ventilated throughout the entire depth of the cloud layer, easily capable of violent tornadoes. As the effects of diurnal heating wanes the temperatures will lower slightly and bring down those LCLs. I am extremely concerned, and haven't personally felt this way about a setup since the 3/31 outbreak.

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Doubt the SPC would upgrade so late in the cycle, but I would be in full support of a tornado driven High Risk from Northeast Arkansas into Eastern Missouri and Southern Illinois. PLEASE take warnings seriously.

Yikes. Thank you for this detailed forecast

 

[SmokeEater]

Maybe the issue of a HIGH (and maybe even a MDT) should warrant WEA on phones?

That will just get people to want to shut them off even more. There's no pending threat to life when an outlook itself is issued. And most people don't care about SPC outlooks, even watches. WEA should focus on warnings only, like it does.

 

[wx_guy]

That will just get people to want to shut them off even more. There's no pending threat to life when an outlook itself is issued. And most people don't care about SPC outlooks, even watches. WEA should focus on warnings only, like it does.

That's a fair point. Just afraid we may have a large number of people who aren't paying attention.

 

[Tennie]

There are several reports of 50-70 MPH winds around the Kansas City vicinity.

 

[Shakespeare 2016]

There are several reports of 50-70 MPH winds around the Kansas City vicinity.

I live near Wichita and the winds are 40 mph with gusts up to 60 mph. My whole house is shaking.

 

[SmokeEater]

That's a fair point. Just afraid we may have a large number of people who aren't paying attention.

All local stations in the affected areas are hammering this threat, and hard. Honestly? At that point there's gotta be some personal responsibility to actually get your head out of the sand and protect your own life.

 

[Evan]

Quasi decent cloud cover here today. My forecasted high was 79. We hit 84 a little while ago. Interested to see if we actually get near the forecasted low tonight. 18z HRRR doesn't have me getting much over 70 tomorrow whereas the NWS is forecasting 77. I say all that to say...I wonder if temps might be a little bit underdone on the HRRR for some areas. If they are, perhaps instability will actually be a bit higher than the healthy amount already being modeled.

We've talked a lot about failure modes. What about factors that could enhance the chances of a higher ceiling type of outcome? Worth discussion, IMO.

 

[Clancy]

Usually I like to comment on how beautiful big storm systems like this are. But today, it just makes me feel a bit sick to look at it.

 

[CheeselandSkies]

IIRC, a High Risk update was done around 22Z for 5/22/2004 (the date of the massive Hallam, NE, tornado).

It was done on the 01Z 5/23 (8 PM CDT 5/22), or the final outlook update for the day, as the Hallam tornado was about to develop. So there is precedent, although of course it was our friend Broyles.

 

[MMWX]

Brandon Copic has some good footage of a wildfire in Missouri.

 

[NorthGaWeather]

This post is principally aimed at Georgian board members: 18Z HRRR is nasty, and in particular, a seriously concerning solution for Atlanta and West Georgia. Deep, moisture-fueled convection in the presence of alarmingly high instability and the already well-discussed extreme helicity will support a threat for multiple highly-dangerous, intense supercells across much of Western Georgia, including Atlanta. With STP values of 3-5 expected across much of the western 1/3rd of the state, I just want to re-emphasize for us Georgia folks to think about the kinds of measures you might need to take as we face a threat for strong tornadoes of a magnitude and areal expanse that we're not particularly used to.

This is going to be bad.

 

[KCweatherboy]

There are several reports of 50-70 MPH winds around the Kansas City vicinity.

Can confirm its been quite windy this afternoon and when storms moved through. At one point I had 35 mph sustained winds and gusts likely to the upper 40s/low 50s mph when the storms were moving through.

 

[TheSuckZone]

 

[Kolle]

My workplace -- the state's largest tourist attraction -- is closing to the public tomorrow. The executive staff sometimes drags their feet on such things, but thankfully the NWS webinar I invited everyone to helped persuade them to the correct decision. Obviously, I would much rather be responsible for 200ish people than 2000.

 

[tornado examiner]

The dust storms are causing major multi car crashes. That’s awful.

 

[Tennie]

There's a duststorm near the DFW area that looks quite unreal:

 

[UpperLevelLOL]

First tornado watch is incoming. Meanwhile, Camargo OK is under direct threat from wildfire per News9

 

[tornado examiner]

This event has already claimed 3 lives. Big pile up on I25. Horrible

 

[Shakespeare 2016]

The house I am renting is cheaply made. It is not that hard to tell. The walls are cheaply made and are creaking because of the winds. A low-end EF3 tornado would blow this house away.

 

[Tennie]

The dust storms are causing major multi car crashes. That’s awful.

Reportedly there are already three fatalities from some of those crashes. In addition, at least one on I-27 is a major pileup (currently no known casualty estimates from that one, but it doesn't sound good...).