April 19th Severe Event

[Santa Clause]

So far mainly spin ups...nothing staying on ground long at all.

[cheese007]

URGENT - IMMEDIATE BROADCAST REQUESTED
   Tornado Watch Number 122
   NWS Storm Prediction Center Norman OK
   240 PM CDT Sun Apr 19 2020

   The NWS Storm Prediction Center has issued a

   * Tornado Watch for portions of 
     Much of Louisiana
     Southwest Mississippi
     Southeast Texas
     Coastal Waters

   * Effective this Sunday afternoon and evening from 240 PM until
     1000 PM CDT.

   * Primary threats include...
     A few tornadoes likely with a couple intense tornadoes possible
     Scattered large hail and isolated very large hail events to 2.5
       inches in diameter likely
     Scattered damaging wind gusts to 70 mph likely

   SUMMARY...Thunderstorms are expected to develop across east Texas
   this afternoon and spread eastward across the watch area through the
   evening.  Large hail and damaging winds are likely with the most
   intense cells.  The risk of a few tornadoes is also increasing as
   winds aloft strengthen.  Strong tornadoes are possible.

   The tornado watch area is approximately along and 150 statute miles
   east and west of a line from 40 miles west northwest of Alexandria
   LA to 65 miles southwest of Intracoastal City LA. For a complete
   depiction of the watch see the associated watch outline update
   (WOUS64 KWNS WOU2).

   PRECAUTIONARY/PREPAREDNESS ACTIONS...

   REMEMBER...A Tornado Watch means conditions are favorable for
   tornadoes and severe thunderstorms in and close to the watch
   area. Persons in these areas should be on the lookout for
   threatening weather conditions and listen for later statements
   and possible warnings.

   &&

   OTHER WATCH INFORMATION...CONTINUE...WW 120...WW 121...

   AVIATION...Tornadoes and a few severe thunderstorms with hail
   surface and aloft to 2.5 inches. Extreme turbulence and surface wind
   gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean
   storm motion vector 25035.

   ...Hart

[Radtechwxman]

Man these VWP's I'm seeing are ugly and not in good way for tornadoes. Very unidirectional. Horribly veered sfc flow

[Moderately Unstable]

Can someone take a look at the storm near Lenox GA and tell me what they think? KVAX is showing a TVS but it is far from the radar site. 

[jpeters3]

1 minute ago, Moderately Unstable said:

Can someone take a look at the storm near Lennox GA and tell me what they think? VAX is showing a TVS but it is far from the radar site. 

It appears to be north of two fairly well defined outflow boundaries, so probably sitting over stable air and unlikely to be tornadic.

[Santa Clause]

4 minutes ago, StormChaser4Life said:

Man these VWP's I'm seeing are ugly and not in good way for tornadoes. Very unidirectional. Horribly veered sfc flow

Saw that as well... looking like it could be something to keep today’s threat minimized.

[JasonOH]

2 minutes ago, Moderately Unstable said:

Can someone take a look at the storm near Lennox GA and tell me what they think? VAX is showing a TVS but it is far from the radar site. 

I don't think that's surface based so there shouldn't be a huge tornado threat from it

[WhirlingWx]

10 minutes ago, StormChaser4Life said:

Man these VWP's I'm seeing are ugly and not in good way for tornadoes. Very unidirectional. Horribly veered sfc flow

For what general area are you looking at those VWP's?

[janetjanet998]

DAY 1 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
0300 PM CDT SUN APR 19 2020  
  
VALID 192000Z - 201200Z  
  
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF  
LA INTO SOUTHERN/CENTRAL MS/AL/GA...  
   
..SUMMARY  
  
A SEVERE-WEATHER OUTBREAK IS EXPECTED ACROSS MUCH OF THE DEEP SOUTH  
THROUGH TONIGHT, WITH THE GREATEST THREAT FROM EAST TEXAS AND THE  
DELTA REGION EASTWARD ACROSS PARTS OF MISSISSIPPI, ALABAMA, AND  
GEORGIA.  MULTIPLE EPISODES OF THUNDERSTORMS WILL LIKELY RESULT IN  
SEVERAL TORNADOES (SOME STRONG), WIDESPREAD DAMAGING WINDS, AND  
LARGE HAIL.  
   
..20Z UPDATE  
  
PRIMARY CHANGE WITH THIS UPDATE WAS TO MAKE ADJUSTMENTS TO THE  
WESTERN EDGE OF HIGHER SEVERE PROBABILITIES ACROSS PARTS OF EAST TX  
INTO LA BASED ON ONGOING STORMS. THE MOST FAVORED CORRIDOR FOR ALL  
SEVERE HAZARDS THROUGH THIS AFTERNOON WILL REMAIN ALONG/SOUTH OF A  
CONVECTIVELY REINFORCED WARM FRONT EXTENDING FROM EAST TX INTO  
CENTRAL LA/MS AND PARTS OF SOUTHERN/CENTRAL AL. 18Z SOUNDINGS FROM  
LCH AND LIX SHOW STRONG LOW-LEVEL FLOW, BUT A WEAKNESS IN THE  
MID-LEVELS ROUGHLY IN THE 750-600 MB LAYER. THIS WEAKNESS IS  
FORECAST TO DIMINISH THIS AFTERNOON AS THE SHORTWAVE TROUGH OVER THE  
SOUTHERN PLAINS CONTINUES TO SHIFT EASTWARD TOWARDS THE LOWER MS  
VALLEY THIS EVENING. A FAVORABLE CORRIDOR FOR STRONG TORNADOES IS  
STILL APPARENT ALONG/SOUTH OF THE WARM FRONT ACROSS PARTS OF CENTRAL  
LA INTO SOUTHERN/CENTRAL MS/AL/GA. BOTH STRONG INSTABILITY AND SHEAR  
WILL BE PRESENT ACROSS THESE AREAS FROM THIS AFTERNOON THROUGH THE  
OVERNIGHT HOURS AS A SOUTHWESTERLY LOW-LEVEL JET AND CORRESPONDING  
LOW-LEVEL SHEAR BOTH STRENGTHEN. AN OUTFLOW BOUNDARY FROM EARLIER  
STORMS DRAPED ACROSS PARTS OF SOUTHERN MS/AL MAY ALSO BE A FOCUS FOR  
GREATER TORNADO POTENTIAL GIVEN LOCALLY BACKED LOW-LEVEL FLOW.  

[Radtechwxman]

2 minutes ago, TexMexWx said:

For what general area are you looking at those VWP's?

Southern MS

[cheese007]

Mesoscale Discussion 0408
   NWS Storm Prediction Center Norman OK
   0303 PM CDT Sun Apr 19 2020

   Areas affected...central AL

   Concerning...Severe potential...Tornado Watch likely 

   Valid 192003Z - 192200Z

   Probability of Watch Issuance...80 percent

   SUMMARY...Thunderstorms will likely intensify over the next several
   hours across central AL.  Timing of a tornado watch issuance will be
   dependent on short-term convective trends from storms currently over
   east-central MS.

   DISCUSSION...Radar imagery shows a west-east cluster of strong
   thunderstorms located from east-central MS through central AL.  The
   thunderstorm activity is located to the north of a composite
   outflow/warm front draped from the southeast corner of AL
   west-northwestward into central MS.  It appears storm development
   during the next few hours will largely cross the warm front and
   become elevated but potentially yield some risk for hail/locally
   damaging gusts.  

   Later this afternoon and especially during the evening, a mid-level
   shortwave trough will move east into the ArkLaTex.  Additional storm
   development and storms moving into the area from the west, will pose
   an increasing risk for severe.  Low-level shear is forecast to
   strengthen through the early evening.  A tornado risk will tend to
   focus with any surface-based supercells.  However, the damaging wind
   risk may concentrate with quickly moving bowing segments that may
   preferentially move eastward along and slightly north of the warm
   front.

   ..Smith/Hart.. 04/19/2020

   ...Please see www.spc.noaa.gov for graphic product...

   ATTN...WFO...TAE...BMX...MOB...JAN...

   LAT...LON   32908836 32768657 31908554 31298570 31568842 32908836 

[jojo762]

Yawn fest so far... for the exact reason as the 00z NSSL-WRF from last night. Just a grungy mess, LLVL wind profile is clearly turning nearly as much as it was on Easter. Likewise still have hours to go, so things could (will) change to some degree.

[SmokeEater]

Yawn fest so far... for the exact reason as the 00z NSSL-WRF from last night. Just a grungy mess, LLVL wind profile is clearly turning nearly as much as it was on Easter. Likewise still have hours to go, so things could (will) change to some degree.

Last event showed that too, many hours to go. Don't get me wrong, I don't think this is anywhere near the magnitude of that one. Just saying. The nocturnal threat may end up being worse than daytime too.

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[jpeters3]

1 minute ago, jojo762 said:

Yawn fest so far... for the exact reason as the 00z NSSL-WRF from last night. Just a grungy mess, LLVL wind profile is clearly turning nearly as much as it was on Easter. Likewise still have hours to go, so things could (will) change to some degree.

Funny that the weenies were going nuts this morning about the lack of a High risk call from SPC.  Seems like another good forecast on their end, given the uncertainty. 

[Radtechwxman]

2 minutes ago, jojo762 said:

Yawn fest so far... for the exact reason as the 00z NSSL-WRF from last night. Just a grungy mess, LLVL wind profile is clearly turning nearly as much as it was on Easter. Likewise still have hours to go, so things could (will) change to some degree.

Couldn't agree more. Good for their sake. But wind profiles are awful. So much veering at sfc. Bad weakness aloft. Storm mode absolute slop fest and definitely outflow dominant 

[rnj79]

The Enhanced Risk are has been expanded south to include NOLA.

[janetjanet998]

6 hours ago, janetjanet998 said:

it looks like outlfows keep the best moisture south...

some models have two warm fronts...the one with the best moisture remains south until very late

if the model radar is correct then pattern recognition is for training outflow dominated sagging storms along the warm front with flooding and wind threats

 

 

 

 

this seems to be happening with a sagging shallow SW moving outflow over GA now almost to the extreme NE FL panhandle seen on KEOX

elevated junk develops over and north it in the LLJ

winds still veered in warm sector and storm motion would take any warm sector storm north of the boundary quickly unless they turn right like a couple storms are trying to do in east MS

 

 

 

 

[StormySquares]

New watch in AL is 90/70 tor probs.

[WhirlingWx]

Does it feel like there are discrepancies between the watch outline and the summary? This new watch outline mentions several tornadoes and a couple intense tornadoes likely yet the summary only states "a few tornadoes" (albeit with the risk of stronger tornadoes).

[WestTennWX]

Decent couplet just south of Snell

[SmokeEater]

TW just NE of Houston also, decent structure.

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[Moderately Unstable]

 

13 minutes ago, TexMexWx said:

Does it feel like there are discrepancies between the watch outline and the summary? This new watch outline mentions several tornadoes and a couple intense tornadoes likely yet the summary only states "a few tornadoes" (albeit with the risk of stronger tornadoes).

Not necessarily. What that reads to me as is, we don't think there will be many tornadoes, but the tornadoes that do occur, will likely be strong. That makes sense, given what has been discussed about storm mode above, and questionable sfc conditions, but concurrently, favorable overall dynamics and elongating hodographs. Fwiw, models do show things getting more favorable late afternoon early evening. 

This whole event, while thus far a snooze fest, has been excellent educationally. It's a complex forecast over a huge area with multiple storm modes, risk types, surface and elevated convection including storms transitioning from one to the other, upscale growth, areas of veering wind vs backing wind, etc. Sometimes in the plains forecasting is almost perfunctory on a gangbusters day. This setup is making everyone have to think, I know I am. 

[Torchageddon]

4 minutes ago, SmokeEater said:

TW just NE of Houston also, decent structure.
 

I noticed that cell when first coming on looking at radar, it didn't have a severe warning on it but now TW?

[StormySquares]

Brief tornado reported west of Quitman, MS

[WhirlingWx]

2 minutes ago, Moderately Unstable said:

What that reads to me as is, we don't think there will be many tornadoes, but the tornadoes that do occur, will likely be strong

Yeah that's what I was wondering, cause that's where I would see it making the most sense.

3 minutes ago, Moderately Unstable said:

This whole event, while thus far a snooze fest, has been excellent educationally. It's a complex forecast over a huge area with multiple storm modes, risk types, surface and elevated convection including storms transitioning from one to the other, upscale growth, areas of veering wind vs backing wind, etc. Sometimes in the plains forecasting is almost perfunctory on a gangbusters day. This setup is making everyone have to think, I know I am. 

Indeed, so many things to consider and track at the same time.

[SouthernNJ]

Still small circulation over Lisman AL with the Quitman-originated storm.  No extension

of the warning from MOB at this time.

[SmokeEater]

Still small circulation over Lisman AL with the Quitman-originated storm.  No extension
of the warning from MOB at this time.

Is now, issued 4 minutes ago.

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[jojo762]

Of course the only Tornado warned cell in the MDT risk area is in a radar hole from hell.

[StormySquares]

When are we getting a radar in Meridian? It's very much needed.

[jojo762]

Imagine (hoping) that the hodographs INVOF the warm front are better than they are in the open warm-sector, because oof...

KPOE:

KLIX:

KMOB: