Easter Weekend Severe Thread

[brianc33710]

Where is the warm front now?

[1900hurricane]

The hodo has really started to enlarge at Del Rio. Despite this, the lone cell has started to struggle some likely due to increasing CIN, and I imagine this will likely kill it off eventually. However, as the lead shrotwave ejects out just ahead of the main trough, ascent increases and convective inhibition decreases, which will give way to the main overnight round as we approach 06Z.

 

[1900hurricane]

8 minutes ago, brianc33710 said:

Where is the warm front now?

I might put it somewhere around here.

 

 

[Sydney Claridge]

15 minutes ago, 1900hurricane said:

The hodo has really started to enlarge at Del Rio. Despite this, the lone cell has started to struggle some likely due to increasing CIN, and I imagine this will likely kill it off eventually. However, as the lead shrotwave ejects out just ahead of the main trough, ascent increases and convective inhibition decreases, which will give way to the main overnight round as we approach 06Z.

That cell definitely seems to be falling apart.  It is no longer severe-warned.  
 

Question is if less convection tonight means there will be less junk convection across the southeast during the day tomorrow.  Though I guess that could depend on the forward motion of the “main round” to develop in the next few hours.

[1900hurricane]

The lead wave looks like it's pushing through Big Bend right now. Main trough is centered back just S of SE Arizona.

 

[brianc33710]

The Day 1 SPC outlook is out. They spread MOD further east, but doesn't upgrade any of the area to High. They didn't even mention potentially pulling the High Risk trigger later today. Everything looks like it's there, but they didn't include any upgrade wording.

 

[cheese007]

Radar indicated Tor warning near Fredricksbeeg TX 

[Sydney Claridge]

4 minutes ago, cheese007 said:

Radar indicated Tor warning near Fredricksbeeg TX 

Correlation coefficient suggests tornado on ground E of Eckert, TX.

[cheese007]

New warning out just north of Waco. Things getting going early...

[Sydney Claridge]

Right turn in the storm approaching Round Mountain could be a problem for the northernmost suburbs of the Austin area (especially Leander and Georgetown) if it continues on this track.

[Sydney Claridge]

Uptick in precipitation cores over Parker, Tarrant, and Hood counties could be a problem for DFW if they intensify.  All the precipitation in the area should be stabilizing things, but SPC Mesoanalysis still indicates plenty of CAPE in the region.  Not thinking too much of it though.

There may even be twin tornadoes south of Marble Falls.  Two tight couplets are showing up on radar velocity.

[Sydney Claridge]

New tornado warning includes Leander and Cedar Park.  This is very concerning now that highly-populated areas are in the path.

[cheese007]

New tor warning heading towards Fairfield, TX

[Witness Protection Program]

Tor warning for Whitehouse & Kilgore, southeast of Tippecanoe & Tyler, too.

https://forecast.weather.gov/wwamap/wwatxtget.php?cwa=fwd&wwa=tornado warning

[janetjanet998]

pretty amazing models had this convective system and mini low days ago at 12z Sunday and then moving across the south

 

MESOSCALE DISCUSSION 0348  
NWS STORM PREDICTION CENTER NORMAN OK  
0718 AM CDT SUN APR 12 2020  
  
AREAS AFFECTED...PARTS OF NORTHEAST TEXAS INTO NORTHERN LOUISIANA  
AND ADJACENT PORTIONS OF SOUTHERN ARKANSAS  
  
CONCERNING...TORNADO WATCH 105...  
  
VALID 121218Z - 121345Z  
  
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 105 CONTINUES.  
  
SUMMARY...POTENTIAL FOR SEVERE WIND GUSTS AND A FEW TORNADOES  
PROBABLY WILL  INCREASE WITH AN INCREASINGLY ORGANIZED MESOSCALE  
CONVECTIVE SYSTEM SPREADING INTO AND ACROSS THE SHREVEPORT LA AREA  
BY 9-10 AM CDT.  
  
DISCUSSION...THE EVOLUTION OF AN INCREASINGLY ORGANIZED MESOSCALE  
CONVECTIVE SYSTEM CONTINUES.  THIS STILL APPEARS TO COINCIDE WITH A  
CORRIDOR OF ENHANCED LOWER/MID TROPOSPHERIC WARM ADVECTION, TO THE  
NORTH OF WARMER AND MORE STRONGLY CAPPING ELEVATED MIXED-LAYER AIR,  
AND JUST AHEAD OF A 50-70 KT WESTERLY 500 MB SPEED MAXIMUM  
PROPAGATING TOWARD THE LOWER MISSISSIPPI VALLEY.  
  
ALTHOUGH THE BOUNDARY LAYER CURRENTLY REMAINS COOLER AND DRIER  
DOWNSTREAM, ACROSS MUCH OF LOUISIANA INTO THE ARK-LA-TEX, INCREASES  
IN SURFACE DEW POINTS ALREADY APPEAR UNDERWAY, AND MORE SUBSTANTIVE  
BOUNDARY-LAYER WARMING AND DESTABILIZATION PROBABLY WILL COMMENCE  
WITH DAYBREAK.    
  
AT LEAST A COUPLE OF SEVERE GUSTS HAVE ALREADY BEEN RECORDED BY ASOS  
AT WACO AND CORSICANA WITH THE PRIMARY ONGOING BOWING SEGMENT IN  
RADAR REFLECTIVITIES, WHICH IS ON TRACK TO REACH THE SHREVEPORT LA  
BY 14-15Z.  WITH THE LATEST RAPID REFRESH SUGGESTING SOUTHERLY 850  
MB FLOW IN THE PROCESS OF STRENGTHENING TO 40-50 KT ACROSS THE UPPER  
TEXAS COASTAL PLAIN INTO THE LOWER MISSISSIPPI VALLEY, THE POTENTIAL  
FOR SEVERE WIND GUSTS SHOULD CONTINUE TO INCREASE GIVEN  
BOUNDARY-LAYER DESTABILIZATION.  COUPLED WITH A STRENGTHENING  
CONVECTIVE COLD POOL, THE POTENTIAL FOR A FEW TORNADOES WITH  
INTENSIFYING MESOVORTICES ALONG THE GUST FRONT MAY ALSO INCREASE  
THROUGH MID TO LATE MORNING.  
  

 

 

[janetjanet998]

HRRR tries to develop discrete cells off and on just ahead of that line 

complex is pretty far south and outflows are pushing more ENE then NE as modeled

 

also cloud debris ahead of it may mess up heating

[janetjanet998]

DAY 1 CONVECTIVE OUTLOOK    
NWS STORM PREDICTION CENTER NORMAN OK  
0752 AM CDT SUN APR 12 2020  
  
VALID 121300Z - 131200Z  
  
...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS TODAY INTO  
TONIGHT FROM THE ARK-LA-MISS EASTWARD INTO AL AND WESTERN GA...  
   
..SUMMARY  
  
AN OUTBREAK OF SEVERE THUNDERSTORMS IS LIKELY TODAY INTO TONIGHT,  
WITH THE GREATEST THREAT EXPECTED FROM MISSISSIPPI ACROSS ALABAMA  
INTO WESTERN GEORGIA. STRONG TORNADOES, WIDESPREAD DAMAGING WINDS,  
AND LARGE HAIL ARE ALL POSSIBLE.  
   
..SYNOPSIS  
  
A COMPLEX FORECAST TODAY WITH MULTIPLE SCENARIOS POSSIBLE ACROSS A  
BROAD AREA FROM THE LOWER MS VALLEY INTO THE TN/OH VALLEYS AND THE  
SOUTHEAST.  A MIDLEVEL TROUGH NEAR THE TX BIG BEND THIS MORNING WILL  
ACCELERATE EAST-NORTHEASTWARD TO THE ARK-LA-MISS BY THIS EVENING AND  
THE APPALACHIANS BY THE END OF THE PERIOD, IN RESPONSE TO CONTINUED  
AMPLIFICATION OF A LARGE-SCALE TROUGH OVER THE NORTH CENTRAL CONUS.  
AT THE SURFACE, A CYCLONE WILL MOVE ACROSS OK TODAY AND DEVELOP  
EASTWARD TO AR BY THIS EVENING, FOLLOWED BY SUBSTANTIAL DEEPENING AS  
THE CYCLONE MOVES NORTHEASTWARD TO THE OH VALLEY/GREAT LAKES  
OVERNIGHT.  A MOIST/UNSTABLE WARM SECTOR WILL SURGE NORTHWARD ACROSS  
LA/MS/AL/GA TODAY, SETTING THE STAGE FOR SEVERE STORMS WITH THE  
EJECTING SHORTWAVE TROUGH AND DEEPENING CYCLONE THROUGH TONIGHT.   
SEVERAL SCENARIOS ARE POSSIBLE WITHIN THE OVERALL OUTLOOK AREA, WITH  
SUBSTANTIAL UNCERTAINTY RELATED TO EARLY/ONGOING CONVECTION NOW IN  
TX.  
   
..NORTHEAST TX TO NORTHERN MS/AL AND TN THIS AFTERNOON  
  
AN ONGOING CLUSTER OF SEVERE STORMS CONTINUES TO MOVE  
EAST-NORTHEASTWARD INTO EAST CENTRAL AND NORTHEAST TX THIS MORNING,  
IN ASSOCIATION WITH A LEAD SHORTWAVE TROUGH.  ALL HAZARDS WILL BE  
POSSIBLE WITH THIS CLUSTER WHICH WILL INCLUDE A MIXED CONVECTIVE  
MODE OF SUPERCELLS AND BOWING SEGMENTS.  LOW-LEVEL MOISTURE WILL  
SURGE NORTHWARD TODAY ACROSS LA/MS/AL IN RESPONSE TO THE DEEPENING  
CYCLONE MOVING FROM OK TO AR.  THE MAIN QUESTION THROUGH MID  
AFTERNOON WILL BE WHETHER OR NOT SURFACE DESTABILIZATION WILL KEEP  
PACE WITH THE INITIAL CLUSTER.  IF WARMING/MOISTENING CAN OCCUR  
QUICKLY ENOUGH, THE CHANCE FOR SURFACE-BASED STORMS ON THE SOUTHERN  
FLANK WILL INCREASE.  THIS MAY OCCUR COINCIDENT WITH AN ENVIRONMENT  
CHARACTERIZED BY MODERATE BUOYANCY (MLCAPE OF 1500-2500 J/KG), VERY  
STRONG LOW-LEVEL SHEAR (0-1 KM SRH OF 400-500 M2/S2) AS THE  
LOW-LEVEL JET STRENGTHENS OVER LA/MS, AND EFFECTIVE BULK SHEAR IN  
EXCESS OF 70 KT.  THIS ENVIRONMENT WILL FAVOR EMBEDDED SUPERCELLS  
CAPABLE OF PRODUCING STRONG TORNADOES AND DAMAGING WINDS.  AGAIN,  
THE MAIN QUESTIONS IN THIS CORRIDOR THROUGH THIS AFTERNOON WILL BE  
THE DEGREE OF ORGANIZATION OF THE LATE MORNING-EARLY AFTERNOON  
CONVECTION, AND ITS PHASING WITH THE SURFACE WARM FRONT.  
   
..MS/AL/GA/CAROLINAS LATE THIS AFTERNOON THROUGH TONIGHT  
  
TO THE SOUTH OF THE INITIAL STORM CLUSTER CROSSING NORTHERN  
MS/AL/TN, A SEPARATE PRE-FRONTAL BAND OF CONVECTION IS EXPECTED TO  
DEVELOP BY LATE AFTERNOON FROM SOUTHERN MS INTO WESTERN/CENTRAL AL.   
THIS CONVECTION WILL BE WELL EAST THE SYNOPTIC COLD FRONT, IN AN  
ENVIRONMENT WITH SURFACE-BASED BUOYANCY AND VERY STRONG VERTICAL  
SHEAR.  A BROKEN BAND WITH EMBEDDED SUPERCELLS APPEARS LIKELY TO  
PERSIST WELL INTO THE OVERNIGHT HOURS, WITH AN ASSOCIATED THREAT FOR  
STRONG TORNADOES AND DAMAGING WINDS.  THE PRE-FRONTAL CONVECTION  
SHOULD REACH THE WESTERN CAROLINAS BY 09-12Z.  
   
..RED RIVER VALLEY THIS AFTERNOON TO THE OH VALLEY OVERNIGHT  
  
AN ARC OF CONVECTION WILL LIKELY FORM THIS AFTERNOON NEAR THE  
SURFACE LOW IN SOUTHEAST OK, AND WITHIN THE LEFT-EXIT REGION OF THE  
MID-UPPER JET.  THIS CONVECTION WILL SUBSEQUENTLY SPREAD EASTWARD  
AND NORTHEASTWARD INTO AR THROUGH LATE AFTERNOON/EVENING.  THE  
NORTHWARD EXTENT OF DESTABILIZATION IN AR/WESTERN TN THIS  
AFTERNOON/EVENING WILL DEPEND LARGELY ON THE INTENSITY AND EXTENT OF  
THE EARLY AFTERNOON CONVECTION MOVING FROM LA INTO NORTHERN MS.   
STILL, STEEP MIDLEVEL LAPSE RATES WITH THE EJECTING MIDLEVEL WAVE  
AND STRONG DEEP-LAYER VERTICAL SHEAR WILL FAVOR FAST-MOVING  
SUPERCELLS AND LINE SEGMENTS CAPABLE OF PRODUCING LARGE HAIL AND  
DAMAGING WINDS.  SIMILAR TO AR THIS AFTERNOON, THE NORTHEAST EXTENT  
OF THE DAMAGING WIND AND TORNADO THREAT INTO TONIGHT WILL DEPEND  
LARGELY ON HOW WIDESPREAD/ORGANIZED THE CONVECTION IS ACROSS  
NORTHERN MS/AL THIS AFTERNOON/EVENING, AND THE DEGREE OF LOW-LEVEL  
RECOVERY IN THE WAKE OF THAT CONVECTION.  

[janetjanet998]

decent discussion in SE forum so lets just move there

 

 

[Indystorm]

SEVERE WEATHER STATEMENT  
NATIONAL WEATHER SERVICE SHREVEPORT LA  
937 AM CDT SUN APR 12 2020  
  
LAC031-121500-  
/O.CON.KSHV.TO.W.0019.000000T0000Z-200412T1500Z/  
DE SOTO LA-  
937 AM CDT SUN APR 12 2020  
  
...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1000 AM CDT FOR CENTRAL  
DE SOTO PARISH...  
          
AT 937 AM CDT, A CONFIRMED TORNADO WAS LOCATED 9 MILES NORTHEAST OF  
LOGANSPORT, OR 12 MILES WEST OF MANSFIELD, MOVING NORTHEAST AT 50  
MPH.  
  
HAZARD...DAMAGING TORNADO AND QUARTER SIZE HAIL.  
  
SOURCE...RADAR CONFIRMED TORNADO.  
  
IMPACT...FLYING DEBRIS WILL BE DANGEROUS TO THOSE CAUGHT WITHOUT   
         SHELTER. MOBILE HOMES WILL BE DAMAGED OR DESTROYED. DAMAGE   
         TO ROOFS, WINDOWS, AND VEHICLES WILL OCCUR.  TREE DAMAGE IS   
         LIKELY.  
  
LOCATIONS IMPACTED INCLUDE...  
MANSFIELD, KEACHI, GRAND CANE, LONGSTREET, GLOSTER, CARMEL, FRIERSON,  
KICKAPOO, KINGSTON AND REEDS STORE.  
  
PRECAUTIONARY/PREPAREDNESS ACTIONS...  

[brianc33710]

I found this regarding the SPC's delay with not going high risk, so far: 

SPC:

THERE IS
STILL ENOUGH UNCERTAINTY WITH REGARD TO CONVECTION OUTPACING
STRONGER SURFACE-BASED INSTABILITY (ESPECIALLY WITH NORTHEAST
EXTENT), AS WELL AS THE OVERALL CONVECTIVE MODE, TO PRECLUDE AN
UPGRADE TO HIGH RISK.

[cheese007]

60% chance of a severe T-storm watch including most of eastern OK and the DFW metroplex: 

https://www.spc.noaa.gov/products/md/md0354.html

[brianc33710]

145 PM CDT SUN APR 12 2020

AREAS AFFECTED...NORTHERN AND CENTRAL ALABAMA AND FAR SOUTHERN
MIDDLE TENNESSEE.

CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY

VALID 121845Z - 122015Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...THE SEVERE WEATHER THREAT CURRENTLY OVER MISSISSIPPI WILL
SHIFT EAST INTO ALABAMA LATER THIS AFTERNOON. A DOWNSTREAM TORNADO
WATCH WILL BE NEEDED SOON.

DISCUSSION...A MCS MOVED ACROSS NORTHERN LOUISIANA THIS MORNING AND
PRODUCED NUMEROUS TDS SIGNATURES. THIS SAME CLUSTER OF STORMS HAS
PRODUCED A TDS MORE RECENTLY (~1830Z) IN WEST-CENTRAL MISSISSIPPI.
THIS SAME LINE OF STORMS IS EXPECTED TO MOVE EAST NORTHEASTWARD INTO
NORTHERN ALABAMA LATER THIS AFTERNOON AND INTO THE EVENING. THE
AIRMASS ACROSS NORTHERN ALABAMA HAS DESTABILIZED ACROSS THE LAST
SEVERAL HOURS AND CONTINUED MOISTENING/WARMING IS EXPECTED AS THE
WARM FRONT LIFTS NORTH. THEREFORE, THIS ONGOING MCS IS EXPECTED TO
MAINTAIN ITS CURRENT INTENSITY AND LIKELY STRENGTHEN FURTHER AS IT
MOVES INTO ALABAMA.

A 997MB MESO-LOW HAS FORMED IN SOUTHEAST AR/WESTERN MS. THIS HAS
ACTED TO LOCALLY ENHANCE THE BACKING OF SURFACE WINDS AHEAD OF THESE
STORMS. THIS HAS LED TO VERY LARGE 0-1 SRH VALUES NEAR 700 M2/S2 PER
GWX VWP. DAMAGING WINDS AND QLCS TORNADOES WILL CONTINUE TO BE A
THREAT WITH THIS MCS AS STORMS MOVE EASTWARD. HOWEVER, THERE IS A
CONDITIONAL THREAT FOR SURFACE BASED SUPERCELLS TO DEVELOP SOUTH OF
THIS ACTIVITY IN THE WARM SECTOR. IF THIS OCCURS, A SIGNIFICANT,
THREAT WOULD BECOME MORE LIKELY.

A TORNADO WATCH WILL BE NEEDED SOON EAST OF THE CURRENT WATCH IN
MISSISSIPPI.

[cheese007]

Severe T-storm watch issued for parts of north TX near the red river and southeast Oklahoma 

[cheese007]

Storm making it way through DFW blew up quick

[aggiegeog]

12 hours ago, cheese007 said:

Storm making it way through DFW blew up quick

That storm did some damage on my family's farm north of Lindale. I'm heading there this morning to help with cleanup. This was the worst storm there since they move there in the early 1980s.

[WhiteoutWX]

On 4/10/2020 at 11:42 AM, WhiteoutWX said:

I think this setup has some potential, but the strong forcing will likely mean a lot of storms. Hodographs are decent in spots but the VBV signature is there in many of them and critical angles are not very ideal. I think you will see a lot of storms struggling to maintain discrete modes. I would bet on a ton of wind and hail reports with mostly weak/brief tornadoes. If we can get some discrete supercells with some deviant easterly motion there could be a strong tornado or two but I am just not seeing large widespread tornado outbreak out of this setup. 

Well looking back I'd say it's hard for me to claim a "correct" forecast out of this, but some of the event did play out as I expected. My biggest mistake was underestimating the strength of some of the QLCS tornadoes, as it appears we had multiple EF3 spinups from the event. However, it did appear that the strong forcing and shear profiles likely both contributed to very messy storm modes for the vast majority of storms, which may have prevented an even more widespread/higher end event. Another potential limiting factor may have been weak low-level lapse rates, especially across northern half to 2/3rds of the risk area. Still, the intense low-level shear was enough in this case to produce dozens of tornado reports. The two supercells that were able to stay discrete and attain some deviant easterly motion produced the most intense tornadic signatures, with the Bassfield, MS prelim rating coming in at EF4 and the trailing storm EF3.

I thought it was also interesting to note that if you look at the SPC reports you can see three clear "swaths" of tornado reports, one with the supercells in southern MS and another tracking through northern LA/MS/AL/GA and into SC associated with a mixed mode QLCS. A third cluster appears along the SC/NC coasts from yesterday morning, also mostly from QLCS. The vast majority of reports for the event came from these three main swaths. Fascinating event for sure and a learning experience for myself.  My heart goes out to all the communities impacted.