April 1-3 Severe Threat

[ZackH]

Honestly 1 significant tornado and a handful of others would easily verify a high risk of this size... 

[pbrussell]

That cluster of cells near Baton Rouge could blow up given the environment they are moving into 

[Santa Clause]

Just now, pbrussell said:

That cluster of cells near Baton Rouge could blow up given the environment they are moving into 

I thought that too, but seems they haven't gotten going much.

[hlcater]

1 minute ago, ZackH said:

Honestly 1 significant tornado and a handful of others would easily verify a high risk of this size... 

How many have there been? Haven't been able to follow, but I've heard of the Jena one and the Alexandria one from twitter

[Upper Level LOL]

2 minutes ago, ZackH said:

Honestly 1 significant tornado and a handful of others would easily verify a high risk of this size... 

Strongly agree, and the kind of Monday morning quarterbacking *in the middle of the outbreak* about whether an event warranted a certain risk level is just annoying and asinine

[JasonOH]

Back to the storms... keep an the on the storms hugging each other just SW of Monticello, MS.  They have been picking up mid level rotation in the last few mins.

[janetjanet998]

besides the old vickburg storm I think the TOR threat is shifting more SE over southern MS and SE LA

SPC will likely go with a moderate risk perhaps a hair south of the last outlook for the overnight hours

 

 

[ZackH]

4 minutes ago, NWLinnCountyIA said:

How many have there been? Haven't been able to follow, but I've heard of the Jena one and the Alexandria one from twitter

There has likely been at least 1 sig tor based on TDS height and VROT values alone, and probably a couple others. There have been a handful of other tornadoes just based on TDS signatures. This high risk has easily verified. 

[MattPetrulli]

My post from SE weather forum for this system, though this is pretty much the main forum for discussion

Complex forecast tomorrow

Squall line will come through in the morning-very early afternoon and won't provide much of a tornado risk unless the squall line breaks up into discrete cells or has cells develop ahead of it. Looks like there will be some air mass recovery across GA/AL and it won't take much sunshine for there to be substantial instability given LLJ strength. Looks like discrete cells develop after this and provide a decent tornado risk throughout the afternoon/evening for GA/AL/SC. One thing tomorrow has that today didn't is that these cells will be more isolated and spread out over a larger area.   Still a lot of uncertainties if these cells can maintain itself and mature into tornado producing supercells. Parameters are certainly there for significant tornadoes though and will need to be watched closely. Still a possibility the squall line completely ruins the setup and turns it into horse crap and useless garbage. Potential is there for some higher-end severe though including strong tornadoes.

 

[janetjanet998]

ENHANCHED

DAY 1 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
0759 PM CDT SUN APR 02 2017  
  
VALID 030100Z - 031200Z  
  
...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR A LARGE  
PART OF SOUTHERN AND CENTRAL LOUISIANA...CENTRAL AND SOUTHERN  
MISSISSIPPI...AND FAR WEST-CENTRAL ALABAMA...  
  
...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM SOUTHWEST  
LOUISIANA NORTHEAST INTO NORTHERN MISSISSIPPI AND WESTERN ALABAMA...  
  
...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS SURROUNDING THE  
SLIGHT RISK...  
   
..SUMMARY  
  
NUMEROUS SEVERE THUNDERSTORMS ARE POSSIBLE TONIGHT OVER THE  
SOUTHEASTERN HALF OF LOUISIANA, MUCH OF MISSISSIPPI, AND WESTERN  
ALABAMA.  WIDESPREAD DAMAGING WINDS ARE POSSIBLE, INCLUDING THE RISK  
FOR A STRONG TORNADO OR TWO DURING THE OVERNIGHT ACROSS PARTS OF  
SOUTHEASTERN LOUISIANA AND SOUTH-CENTRAL MISSISSIPPI.  
   
..CENTRAL GULF COAST STATES  
  
AN EXTENSIVE SQUALL LINE FROM THE LOWER SABINE VALLEY NORTHEASTWARD  
INTO NORTHERN MISSISSIPPI WILL SERVE AS THE WESTERN DELIMITER FOR  
STRONG/SEVERE THUNDERSTORMS TONIGHT.  A VERY MOISTURE-RICH AIR MASS  
SOUTH OF A WARM FRONT OVER SOUTHERN MS WILL GRADUALLY ADVANCE  
NORTHWARD INTO CENTRAL MS TONIGHT AND SOUTHWESTERN AL.  STEEP  
700-500 MB LAPSE RATES (7 DEGREES C/KM) SAMPLED IN THE WARM SECTOR  
FROM 00Z LCH AND LIX RAOBS ARE CONTRIBUTING TO MODERATE BUOYANCY  
(2500 J/KG MLCAPE).  AS THE MID-LEVEL TROUGH OVER TX PIVOTS  
NORTHEAST TOWARDS THE OZARKS TONIGHT, THE STRONG LOW-LEVEL AND  
DEEP-LAYER SHEAR PROFILES WILL REMAIN IN PLACE ACROSS THE WARM  
SECTOR.  ISOLATED CELLS MAY CONTINUE TO DEVELOP AHEAD OF THE SQUALL  
LINE AND POSE A RISK FOR LARGE HAIL, DAMAGING GUSTS, AND A TORNADO  
(POSSIBLY STRONG/DAMAGING) GIVEN THE LARGE LOOPING HODOGRAPHS  
SAMPLED BY AREA 88D VAD WINDS.  SHORT-TERM MODELS SUGGEST AN  
ACCELERATION OF THE SOUTHERN PORTION OF THE SQUALL LINE ACROSS LA  
AND MS TONIGHT.  WIDESPREAD DAMAGING WINDS ARE POSSIBLE WITH THE  
SQUALL LINE, ESPECIALLY NEAR LARGE EMBEDDED CORES WHERE AN EMBEDDED  
SUPERCELL TORNADO AND/OR MESOVORTEX-TORNADO RISK MAY DEVELOP.    
  
FARTHER EAST, THE 00Z BMX RAOB NORTH OF THE WARM FRONT WAS  
DRY/STABLE.  YET, STRONG LOW-LEVEL FLOW WITH ACCOMPANYING MOISTURE  
WILL GRADUALLY DESTABILIZE THE EASTERN PARTS OF MS INTO AL DURING  
THE OVERNIGHT.  MODELS SUGGEST THE PRE-FRONTAL SQUALL LINE WILL MOVE  
INTO THIS AREA DURING THE 06-12Z PERIOD.  ISOLATED DAMAGING WINDS  
WILL BE THE PRIMARY THREAT BUT A TORNADO IS POSSIBLE FARTHER SOUTH  
IN CLOSER PROXIMITY TO THE RICHER MOISTURE. 

[Jim Martin]

Tornado Watch forthcoming for Southwest Louisiana and Southeast Texas per SPC.

[Jonbo]

https://www.twitter.com/ThetaShear/status/848647198275502080

Gives some perspective to the amount of debris the Jena tornado had lofted.

[Jim Martin]

3 minutes ago, Jonbo said:

https://www.twitter.com/ThetaShear/status/848647198275502080

Gives some perspective to the amount of debris the Jena tornado had lofted.

Holy cow...

[Jonbo]

51 minutes ago, ZackH said:

There has likely been at least 1 sig tor based on TDS height and VROT values alone, and probably a couple others. There have been a handful of other tornadoes just based on TDS signatures. This high risk has easily verified. 

It's basically guaranteed to have had at least 1 sig tor today, just from Jeff Piotrowski's short video on Twitter. A matter of waiting for the NWS survey team to confirm it.

 

[SouthernNJ]

Looks like a circulation is trying to get

going in the line near Sharon MS.

[Santa Clause]

Currently only two severe warnings present, flooding still a big threat though.

[SmokeEater]

Think flooding is the big threat for the rest of the night now. Especially in areas that were hit earlier. Now to see what tomorrow is gonna bring.

[Tater Tot]

5 hours ago, Derecho! said:

So Louisiana Governor just told people to shelter under overpasses in a press conference.

OMG 

One of the impressive things about today was how "crowded" all the activity was and yet most of the cells still managed to fire off.

[Derecho!]

5 hours ago, CGChaser said:

Link?

Sorry was out all evening.

It was a live press conference shown on the Wx Channel. 

[SmokeEater]

Any chance we can talk tomorrow in here? The SE thread is mostly posting about the Carolinas, lol.

[thomp2mp]

not even any Severe Thunderstorm Warnings attm. might as well post about the southeast's chances for ****ery tomorrow.

[Chinook]

1 hour ago, SmokeEater said:

Any chance we can talk tomorrow in here? The SE thread is mostly posting about the Carolinas, lol.

I think there's quite a bit of uncertainty regarding what happens after the big squall line moves through E Alabama and W Georgia and (perhaps) breaks up. The NAM has quite a bit of MUCAPE showing in E Alabama in the afternoon/evening. You would think that would increase the potential for discrete supercells later in the day. With some 3000 J/kg and 51 kt of shear at 00z (7PM central time). So there may some widely scattered severe weather on the west side of the squall line.  The WRF-ARW and WRF-NMMB show very low chances of severe weather on the west side.

Obvious chances for wind damage near the Gulf with the squall line. Shear is pretty high, so there may be an area that gets a lot of wind reports, all in a row.

On the east side of things, there's a chance that supercells could get going fairly far east (like near or west of Savannah GA, Florida coastline). I'd say the 00z 3km NAM may be a little trigger-happy with these large cells.  But then again, the 00z WRF-ARW (data just came in) has several discrete cells in the GA/SC border area.  I think the SPC will extend the slight risk to a section of the Florida peninsula. East Georgia is not normally tornado-country or hail-country. But, what the heck, 2017 is a really big tornado year so far, so maybe we will see several tornado and hail reports in eastern Georgia or western South Carolina.