Archive March 18-20th, 2018 Severe Weather

[Richardjacks]

I could see this going to Mod

 

[Richardjacks]

The biggest change in the models over the last 12-24 hours is that the confluence in the east is weaker, so the vort max is not deamplifying as quickly and also in turn isn't moving as quickly compared to yesterday's runs. Also a secondary piece of vorticity is swinging around the back side which looks to be the lobe of vorticity touching off the storms by 21z tomorrow. It is that second piece that gets its act together more overnight tomorrow night and leads to the severe weather for northern Florida on Tuesday as it swings through.

that makes sense, haven't had a chance to look at the 500mb flow, maybe I can dive into that later.

 

[Austin Dawg]

I live in Austin, TX. When we have rain and then a hard enough push of dry air to have fire watch weather the next day, there is usually a big problem over in the mid-south.

There is going to definitely be a strong push of dry air coming out of Texas with this system.


Near critical fire weather conditions are still expected across parts
Area Forecast Discussion...UPDATED
National Weather Service Austin/San Antonio TX
1253 PM CDT Sun Mar 18 2018

Elevated fire weather conditions are expected to spread
into the western Hill Country and eastern portions of the Rio Grande
Plains this afternoon as relative humidity values briefly drop to
20-25 percent before the dryline retreats west early this evening.

Critical fire weather conditions over at least the western half of
South Central Texas is still expected for tomorrow, so we will most
likely upgrade the Fire Weather Watch to a Red Flag Warning for
tomorrow with the afternoon package. Eastward expansion of the Fire
Weather Watch into the I-35 corridor and possibly further east is
also expected as near critical fire weather conditions are becoming
more likely and critical conditions may be possible based some models
that are trending towards increasing wind speeds in the afternoon.

 

[Equus]

Really don't have all that many plains-style hail threats in these parts, so tomorrow will be very interesting, even tornadoes notwithstanding. I do hope someone thinks to DVR local coverage if there are tornado warnings.

 

[akt1985]

With the way the SPC has the severe weather area set up, are the super cells tomorrow expected to move east or even southeast instead of northeast?

 

[Fred Gossage]

The Euro, the least serious of all the model solutions for this threat for days, has now fallen in line with the more serious solution. The 12Z run now has much more southwesterly 850mb winds late tomorrow than the westerly winds of previous runs... and they are now approaching 50 kts. The Euro also backs the surface winds to SSE ahead of its prefrontal trough feature (although it is faster with the track of this, but it still does this from MS eastward across TN/AL from west to east). This leads to the Euro now depicting 3km SRH of 400 and greater over central Alabama and an EHI of up to 5. The least bullish model for days has now fallen in line.

 

[warneagle]

that model is showing Dec 16 2000 sounding match for BHM...that was the F4 Tuscaloosa tornado...also I think it is significant that a warm season event is triggering a cool season match

Yeah, that's not a good sign.

 

[CheeselandSkies]

Also spotted 00Z BMX sounding for the evening of 4/16/98 as an analog off one of the 3K NAM soundings...day of the Nashville tornadoes and multiple violent tornadoes in southern TN, although I don't think there was anything similarly significant in AL that day.

 

[Bamamuscle]

Also spotted 00Z BMX sounding for the evening of 4/16/98 as an analog off one of the 3K NAM soundings...day of the Nashville tornadoes and multiple violent tornadoes in southern TN, although I don't think there was anything similarly significant in AL that day.

Was that the Lawerence Co. “forgotten” EF-5 event?


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[rolltide_130]

18z run is bad for Huntsville.. it's really, really bad..

 

[tennessee storm chaser]

Was that the Lawerence Co. “forgotten” EF-5 event?


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that is correct...

 

[Richardjacks]

The biggest change in the models over the last 12-24 hours is that the confluence in the east is weaker, so the vort max is not deamplifying as quickly and also in turn isn't moving as quickly compared to yesterday's runs. Also a secondary piece of vorticity is swinging around the back side which looks to be the lobe of vorticity touching off the storms by 21z tomorrow. It is that second piece that gets its act together more overnight tomorrow night and leads to the severe weather for northern Florida on Tuesday as it swings through.

It seems the 18z nam is also showing the second vort max with the surface continuing to deepen- now 993mb!
While the spatial area is not huge, the threat seems to be upper scale...perhaps warranting high risk.

 

[tennessee storm chaser]

It seems the a8z nam is also showing the second vort max with the surface continuing to deepen- now 993mb!
While the spatial area is not huge, the threat seems to be upper scale...perhaps warranting high risk.

so you think spc may start out in morning update, moderate risk... with potentially up grade to a small area of high risk in noon update tomorrw?

 

[stebo]

It seems the a8z nam is also showing the second vort max with the surface continuing to deepen- now 993mb!
While the spatial area is not huge, the threat seems to be upper scale...perhaps warranting high risk.

I wouldn't quite go that far yet but I do think this will get upgraded to a moderate if current trends continue. If they were to compound even further, then maybe. That would be something we'd see uparaded tomorrow when the mesoscale is resolved further.

 

[Argus]

The Day 2 slight risk now extends east to Carlton, Georgia, after the new update.

 

[Richardjacks]

I wouldn't quite go that far yet but I do think this will get upgraded to a moderate if current trends continue. If they were to compound even further, then maybe. That would be something we'd see uparaded tomorrow when the mesoscale is resolved further.

Yes, there are a few mesoscale issues to resolve, such as cloud cover and how clean the warm sector and how much low level winds are backed...assuming those are worked out, an upgrade may be possible by morning...it would be a fairly small area that would be high...this is a fairly compact setup.

 

[Mike S]

 

[Weatherphreak]

18z run is bad for Huntsville.. it's really, really bad..

Amateur question: on a scale of 0-11 this is an 11 on significant tornado parameters for Huntsville tomorrow?
Also is 0.15 a sample value or is anything over that considered significant?

 

[rolltide_130]

The HRRRx panel is unbelievable..

 

[rolltide_130]

I'm just gonna be upfront here and say it...

Tomorrow is our most threatening day since 4/27/11. It could still trend down or not be as bad as it appears, but this is turning into a horrific situation. Have your action plan in place TONIGHT.