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April 12 Severe Event


joshwx2003
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MESOSCALE DISCUSSION 0350  
NWS STORM PREDICTION CENTER NORMAN OK  
1024 AM CDT SUN APR 12 2020  
  
AREAS AFFECTED...PORTIONS OF NORTHEASTERN LA...NORTHERN/CENTRAL  
MS...AND FAR SOUTHEASTERN AR  
  
CONCERNING...SEVERE POTENTIAL...TORNADO WATCH LIKELY   
  
VALID 121524Z - 121700Z  
  
PROBABILITY OF WATCH ISSUANCE...95 PERCENT  
  
SUMMARY...THE SEVERE THREAT WILL MARKEDLY INCREASE BY THIS  
AFTERNOON, WITH STRONG TORNADOES, NUMEROUS DAMAGING WINDS, AND LARGE  
HAIL ALL LIKELY. A TORNADO WATCH WILL BE REQUIRED ACROSS  
NORTHERN/CENTRAL MS AND NORTHEASTERN LA SHORTLY.  
  
DISCUSSION...THE AIRMASS ACROSS NORTHEASTERN LA INTO CENTRAL MS  
DOWNSTREAM OF A QLCS IN NORTHERN LA IS RAPIDLY DESTABILIZING. A WARM  
ADVECTION WING OF ELEVATED CONVECTION HAS DEVELOPED ACROSS THIS AREA  
AS A MARINE WARM FRONT CONTINUES TO LIFT NORTHWARD. SURFACE  
DEWPOINTS ARE EXPECTED TO QUICKLY INCREASE INTO THE UPPER 60S TO  
LOWER 70S ALONG/SOUTH OF THE NORTHWARD-ADVANCING WARM FRONT AS A  
STRONG LOW-LEVEL MASS RESPONSE OCCURS OVER THE ARKLATEX REGION THIS  
AFTERNOON. WITH CONTINUED DIURNAL HEATING, MLCAPE SHOULD INCREASE  
INTO THE 1500-3000 J/KG RANGE BY PEAK AFTERNOON HEATING. VERY STRONG  
SHEAR IS FORECAST TO BE PRESENT FROM LOW THROUGH MID LEVELS, WHICH  
WILL SUPPORT ROBUST STORM ORGANIZATION BOTH WITH THE ONGOING QLCS  
AND WITH ANY CELLS THAT CAN FORM FARTHER SOUTH/EAST ACROSS THE OPEN  
WARM SECTOR. LATEST VWP FROM KDGX (JACKSON, MS) SHOWS SUBSTANTIAL  
LOW-LEVEL HODOGRAPH CURVATURE, WITH 0-1 KM SHEAR APPROACHING 50 KT,  
AND 0-1 SRH AROUND 500 M2/S2. STRONG TORNADOES MAY OCCUR GIVEN THE  
STRENGTH OF THE LOW-LEVEL FLOW, ALONG WITH NUMEROUS DAMAGING WINDS  
IF THE STORM MODE REMAINS MOSTLY LINEAR. THERE IS STILL SOME  
UNCERTAINTY REGARDING SUPERCELL POTENTIAL ACROSS NORTHERN/CENTRAL MS  
THIS AFTERNOON. IF ANY STORMS CAN FORM FARTHER SOUTH/EAST OF THE  
ONGOING QLCS, THEY WILL ENCOUNTER A STRONGLY UNSTABLE AND SHEARED  
ENVIRONMENT FAVORABLE FOR ALL SEVERE HAZARDS.  
  

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3 minutes ago, Cheeznado said:

I bet SPC is pondering an upgrade to high. 14Z HRRR shows an increase in the number of significant UH tracks.

Screen Shot 2020-04-12 at 11.26.55 AM.png

Though, the HRRR solution is showing a lot of this activity (aside from the huge UH tracks with the QLCS) along the tail end of the line.  So far, this region as been fairly inactive. 


Edit: after another look, I'm having trouble interpreting what the model is showing.  At one glance, I can convince myself that it shows widespread supercell coverage.  At another glance, I can convince myself that it's just showing a QLCS mess.  Either way, it seems every probable that numerous QLCS tornadoes will happen today given this morning's trend, and that some of them might be strong.  That alone, along with the more uncertain warm sector, might be enough to warrant an upgrade to HIGH.

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I think it's time to go High Risk today. The fact that a large tornado just occurred within a QLCS during the morning before diurnal heating and the deepening of the low has occurred is really something. Growing up in the Great Lakes region so many classic outbreaks and strong tornadoes I have chased featured solid instability, great dews around 70° and SRH's of 250-350. Today's numbers, especially in SRH are blowing this out of the water. To see such stark numbers suggest any strong updraft may rotate, and violently at that at times.

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7 minutes ago, Cheeznado said:

I bet SPC is pondering an upgrade to high. 14Z HRRR shows an increase in the number of significant UH tracks.

Screen Shot 2020-04-12 at 11.26.55 AM.png

moderate or high I don't think really maters at this point. it's probably more a worry now of PDS tornado Watches and normal Tornado Watches than anything else.

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Just now, Jim Marusak said:

moderate or high I don't think really maters at this point. it's probably more a worry now of PDS tornado Watches and normal Tornado Watches than anything else.

Obviously SPC outlooks have no impact on what will actually happen, but it's fun to speculate on what the SPC forecasters will do.

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RGENT - IMMEDIATE BROADCAST REQUESTED  
TORNADO WATCH NUMBER 106  
NWS STORM PREDICTION CENTER NORMAN OK  
1040 AM CDT SUN APR 12 2020  
  
THE NWS STORM PREDICTION CENTER HAS ISSUED A  
  
* TORNADO WATCH FOR PORTIONS OF   
  FAR SOUTHEAST ARKANSAS  
  NORTHEAST LOUISIANA  
  NORTHERN AND CENTRAL MISSISSIPPI  
  
* EFFECTIVE THIS SUNDAY MORNING AND EVENING FROM 1040 AM UNTIL  
  800 PM CDT.  
   
..THIS IS A PARTICULARLY DANGEROUS SITUATION  
  
* PRIMARY THREATS INCLUDE...  
  SEVERAL TORNADOES AND A FEW INTENSE TORNADOES LIKELY  
  WIDESPREAD DAMAGING WINDS LIKELY WITH ISOLATED SIGNIFICANT GUSTS  
    TO 80 MPH POSSIBLE  
  SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2  
    INCHES IN DIAMETER POSSIBLE  
  
SUMMARY...INTENSE BOWING LINE WITH A HISTORY OF SEVERAL TORNADOES IN  
NORTHWEST LOUISIANA WILL PROGRESS RAPIDLY EAST-NORTHEAST THIS  
AFTERNOON. ADDITIONAL SEMI-DISCRETE SUPRECELLS MAY DEVELOP AHEAD OF  
THE LINE AS WELL ACROSS PARTS OF NORTHERN AND CENTRAL MISSISSIPPI.  
ENVIRONMENT IS SUPPORTIVE OF SEVERAL TORNADOES, SOME OF WHICH WILL  
LIKELY BE STRONG IN ADDITION TO POTENTIAL WIDESPREAD DAMAGING WINDS. 

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Just now, janetjanet998 said:

RGENT - IMMEDIATE BROADCAST REQUESTED  
TORNADO WATCH NUMBER 106  
NWS STORM PREDICTION CENTER NORMAN OK  
1040 AM CDT SUN APR 12 2020  
  
THE NWS STORM PREDICTION CENTER HAS ISSUED A  
  
* TORNADO WATCH FOR PORTIONS OF   
  FAR SOUTHEAST ARKANSAS  
  NORTHEAST LOUISIANA  
  NORTHERN AND CENTRAL MISSISSIPPI  
  
* EFFECTIVE THIS SUNDAY MORNING AND EVENING FROM 1040 AM UNTIL  
  800 PM CDT.  
   
..THIS IS A PARTICULARLY DANGEROUS SITUATION  
  
* PRIMARY THREATS INCLUDE...  
  SEVERAL TORNADOES AND A FEW INTENSE TORNADOES LIKELY  
  WIDESPREAD DAMAGING WINDS LIKELY WITH ISOLATED SIGNIFICANT GUSTS  
    TO 80 MPH POSSIBLE  
  SCATTERED LARGE HAIL AND ISOLATED VERY LARGE HAIL EVENTS TO 2  
    INCHES IN DIAMETER POSSIBLE  
  
SUMMARY...INTENSE BOWING LINE WITH A HISTORY OF SEVERAL TORNADOES IN  
NORTHWEST LOUISIANA WILL PROGRESS RAPIDLY EAST-NORTHEAST THIS  
AFTERNOON. ADDITIONAL SEMI-DISCRETE SUPRECELLS MAY DEVELOP AHEAD OF  
THE LINE AS WELL ACROSS PARTS OF NORTHERN AND CENTRAL MISSISSIPPI.  
ENVIRONMENT IS SUPPORTIVE OF SEVERAL TORNADOES, SOME OF WHICH WILL  
LIKELY BE STRONG IN ADDITION TO POTENTIAL WIDESPREAD DAMAGING WINDS. 

That was really quick from MD to actual watch.

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EVERE WEATHER STATEMENT  
NATIONAL WEATHER SERVICE SHREVEPORT LA  
1047 AM CDT SUN APR 12 2020  
  
LAC013-027-061-121600-  
/O.CON.KSHV.TO.W.0026.000000T0000Z-200412T1600Z/  
CLAIBORNE LA-BIENVILLE LA-LINCOLN LA-  
1047 AM CDT SUN APR 12 2020  
  
...A TORNADO WARNING REMAINS IN EFFECT UNTIL 1100 AM CDT FOR  
SOUTHEASTERN CLAIBORNE...NORTH CENTRAL BIENVILLE AND NORTHWESTERN  
LINCOLN PARISHES...  
          
AT 1046 AM CDT, A CONFIRMED TORNADO WAS LOCATED OVER ARCADIA, OR 13  
MILES WEST OF GRAMBLING, MOVING NORTHEAST AT 45 MPH.  
  
HAZARD...DAMAGING TORNADO.  
  
SOURCE...RADAR CONFIRMED TORNADO.  

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Why wouldn't rotation be displayed when there's a TDS? Genuinely ignorant on this, thanks for any info!
Meaning the rotation isn't strong at all, and it has a confirmed tornado producing a TDS. Just saying it's not taking much at all with the dynamics at play today.

 

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BULLETIN - EAS ACTIVATION REQUESTED  
TORNADO WARNING  
NATIONAL WEATHER SERVICE SHREVEPORT LA  
1056 AM CDT SUN APR 12 2020  
  
THE NATIONAL WEATHER SERVICE IN SHREVEPORT HAS ISSUED A  
  
* TORNADO WARNING FOR...  
  SOUTHWESTERN UNION PARISH IN NORTH CENTRAL LOUISIANA...  
  SOUTH CENTRAL CLAIBORNE PARISH IN NORTHWESTERN LOUISIANA...  
  NORTHEASTERN BIENVILLE PARISH IN NORTHWESTERN LOUISIANA...  
  CENTRAL LINCOLN PARISH IN NORTH CENTRAL LOUISIANA...  
  
* UNTIL 1130 AM CDT.  
      
* AT 1055 AM CDT, A TORNADO PRODUCING STORM WAS LOCATED NEAR ARCADIA,  
  OR 9 MILES NORTHWEST OF GRAMBLING, MOVING NORTHEAST AT 35 MPH.  
  
  HAZARD...DAMAGING TORNADO.  
  
  SOURCE...RADAR CONFIRMED TORNADO.  

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4 minutes ago, SmokeEater said:

Meaning the rotation isn't strong at all, and it has a confirmed tornado producing a TDS. Just saying it's not taking much at all with the dynamics at play today.

 

Sent from my SM-G973U using Tapatalk

 

 

 

LCL's are so low (500-750) across most of risk area today. It is going to take nothing to drop a tornado considering parcels are condensing already within 2000 feet

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