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andyhb

April 26th-30th, 2014 Major Tornado Outbreak

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That's what happens when you don't have a well-established cold pool.  The unstable atmosphere rapidly readvects in, and you're back to square one.

Yes indeed, DP up to 63 here now, air temp 71

 

Any thoughts on when the dryline refires?

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On a different note, DP's 75 mins ago at my house were down to 52, now according to mesonet back up to 61. Ambient temps back up 10 degrees from 57 to 67....

Makes me concerned for areas that will have more time to rebound before the DL passes their area.

any return of the southerly srf winds? I assume yes... Will be interesting to see if storms redevelop along the boundary in OK and perhaps S Kansas with all this clearing/ sun to work with... No CU field developing attm either...

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Yup.. what's with all that junky looking convection down by you? Looks like it's right over you now? Just rain?

 

EDIT: Just warned for Hail.

Storm really just east of me... no hail here, but heavy rain. 

 

TSA has adjusted their timing... slowing down the timing of storms. 

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Rich Thompson is probably one of the most skilled and experienced forecasters at SPC. It is ok to disagree, but try and add some value to the discussion. Let us not turn this into a SPC vs "my forecast" thread.

 

The reduction of the MOD risk to the N is justified given the latest convective trends. And also understand that the risk categories are probability based. 

 

Continue on.

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That temperature differential setting up across central/southern AR due to the cloud cover and morning convection looks rather ominous for tornadic supercells later.  It should increase the vorticity.  

 

Explosion of elevated convection in northern AR should reinforce that boundary too.

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Rich Thompson is probably one of the most skilled and experienced forecasters at SPC. It is ok to disagree, but try and add some value to the discussion. Let us not turn this into a SPC vs "my forecast" thread.

 

The reduction of the MOD risk to the N is justified given the latest convective trends. And also understand that the risk categories are probability based. 

 

Continue on.

 

Strongly agree. If you are going to critique the outlook, do it with substance. And keep in mind the definition of a high risk based on tornado probabilities. Does the current situation warrant the upgrade of an area from 15% to 30% tor? And why? A high risk denotes the ultimate level of certainty in a tornado (or damaging wind) outbreak. And there is plenty of uncertainty instilled in the forecast today.

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For anyone interested, I am trying to get a discussion going of the fundamentals of this situation in THE ROLE OF EMLS IN SEVERE ... .  I would love some wise comment on the Shreveport skewT posted there.  Won't say more here in fear of cross posting.  N

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MCD for a watch just issued for the highest threat areas.

 

EFwXxe9.gif

MESOSCALE DISCUSSION 0420
NWS STORM PREDICTION CENTER NORMAN OK
1225 PM CDT SUN APR 27 2014

AREAS AFFECTED...ERN OK...NERN TX THROUGH WRN AND CNTRL ARKANSAS

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 271725Z - 271930Z

PROBABILITY OF WATCH ISSUANCE...95 PERCENT

SUMMARY...THE ATMOSPHERE IS EXPECTED TO BECOME INCREASINGLY
FAVORABLE FOR LONG TRACK SUPERCELLS CAPABLE OF TORNADOES...A FEW OF
WHICH COULD BE STRONG BY MID-LATE AFTERNOON. LARGE HAIL AND DAMAGING
WIND WILL ALSO BECOME LIKELY WITH THE STRONGER STORMS. MESOSCALE AND
CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED...AND A TORNADO
WATCH WILL LIKELY BE NEEDED BY 19Z-20Z.

DISCUSSION...EARLY THIS AFTERNOON A PACIFIC COLD FRONT EXTENDS FROM
ERN KS SWD THROUGH CNTRL OK INTO NCNTRL TX. A WARM FRONT WAS LOCATED
FROM NRN MS THROUGH CNTRL ARKANSAS. THE WARM SECTOR BETWEEN THESE
BOUNDARIES CONTINUES TO DESTABILIZE AS A STRONG LLJ ADVECTS UPPER
60S DEWPOINTS NWD BENEATH STEEP LAPSE RATES. HOWEVER...THE RATE OF
BOUNDARY LAYER DESTABILIZATION HAS BEEN SLOWED BY MULTILAYER CLOUDS
INCLUDING STRATUS AND CONVECTIVE DEBRIS. LATEST VISIBLE IMAGERY DOES
SHOW NUMEROUS CLOUD BREAKS...AND THE STRATUS DECK OVER CENTRAL
ARKANSAS MAY EVENTUALLY ERODE FROM THE SOUTH. AN AXIS OF 1500-2500
J/KG MLCAPE WILL DEVELOP ACROSS THIS REGION THIS AFTERNOON.

A PRE-FRONTAL BELT OF ASCENT WITH WHAT APPEARS TO BE AN EWD
PROPAGATING GRAVITY WAVE CONTINUES FROM WRN ARKANSAS THROUGH NWRN
TX. MEANWHILE AN UPPER JET STREAK ROTATING THROUGH BASE OF THE UPPER
TROUGH WILL SHIFT EWD THROUGH NRN TX INTO THE LOWER MS VALLEY.
FORCING FOR ASCENT ASSOCIATED WITH THESE FEATURES AS WELL AS
BOUNDARY LAYER WARMING SHOULD EVENTUALLY WEAKEN THE CAP SUFFICIENTLY
FOR SURFACE BASED THUNDERSTORM DEVELOPMENT WITHIN AXIS OF
PRE-FRONTAL CONFLUENCE IN WARM SECTOR...AS WELL AS ALONG THE PACIFIC
FRONT. STRENGTHENING WIND PROFILES ASSOCIATED WITH THE APPROACHING
UPPER JET AND FAVORABLE LOW-LEVEL HODOGRAPHS WILL SUPPORT SUPERCELLS
WITH LOW-LEVEL MESOCYCLONES CAPABLE OF PRODUCING TORNADOES AND LARGE
HAIL. THE 0-1 KM HODOGRAPHS APPEAR MAXIMIZED ACROSS CNTRL AR WHERE
LOW-LEVEL WINDS REMAIN BACKED IN VICINITY OF THE WARM FRONT THAT IS
CURRENTLY BEING REINFORCED BY ELEVATED CONVECTION.

..DIAL/THOMPSON.. 04/27/2014

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Anybody think there could be any kind of substantial redevelopment along the dryline in central OK through SC Kansas? Given the possible return of low/mid sixties dp's, rising temps and instability? Crapvection really only temporally appears to have turned over the atmosphere, and dryline surprisingly hasnt begun to surge eastward yet. No CU development to speak of right now though.

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Will be interesting to see if any of the watches this afternoon get a PDS label on them.

I think you'll see the Ark watch get PDS.  Based on the meso analysis that I'm seeing and the hires model prediction.

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Hardly any changes to the Day 2 outlook. Slight risk was expanded into central NC, the Illinois/Iowa area got a hatched contour. No change to the Moderate risk itself, though the significant severe weather contour was expanded farther east.

 

 

 

DAY 2 CONVECTIVE OUTLOOK 
   NWS STORM PREDICTION CENTER NORMAN OK
   1230 PM CDT SUN APR 27 2014

   VALID 281200Z - 291200Z

   ...THERE IS A MDT RISK OF SVR TSTMS ACROSS MUCH OF MS...NRN
   AL...TN...NERN LA...

   ...THERE IS A SLGT RISK OF SVR TSTMS FROM IA AND IL SWD ACROSS THE
   OH...TN...THE MID/LOWER MS VALLEY EWD TO THE WRN CAROLINAS...

   ...SUMMARY...
   WIDESPREAD SEVERE STORMS INCLUDING STRONG TORNADOES...DAMAGING WINDS
   AND VERY LARGE HAIL APPEAR LIKELY MONDAY AND MONDAY NIGHT ACROSS
   MUCH OF MISSISSIPPI...NORTHERN ALABAMA...TENNESSEE...SOUTHERN
   KENTUCKY...AND NORTHEASTERN LOUISIANA.

   ...SYNOPSIS...
   LOW-PRESSURE WILL BECOME VERTICALLY STACKED OVER ERN NEB AND IA
   DURING THE DAY WITH LEADING JET MAX DEVELOPING NEWD FROM THE
   ARKLATEX INTO THE LOWER OH VALLEY. AN OCCLUDED FRONT WILL EXTEND EWD
   FROM THE LOW ACROSS IA AND NRN IL...WITH WARM FRONT LIFTING NWD
   ACROSS INDIANA AND OHIO. A COLD FRONT WILL EXTEND SWD FROM THE
   LOW...ARCING RAPIDLY NEWD ACROSS THE MID MO RIVER VALLEY DURING THE
   DAY AND BECOMING STATIONARY ACROSS THE LOWER MS RIVER VALLEY BY LATE
   AFTERNOON. AN UNSTABLE AND MOIST ENVIRONMENT WILL EXIST AHEAD OF THE
   COLD FRONT WITH SHEAR PROFILES FAVORABLE FOR SEVERE THUNDERSTORMS
   ACROSS A LARGE AREA FROM IA TO THE CNTRL GULF COAST.

   TO THE E...A FRONT WILL GRADUALLY RETREAT NWD ACROSS NC...ALLOWING
   FOR DESTABILIZATION AND A THREAT OF ISOLATED SEVERE STORMS THERE.

   ...LOWER MS VALLEY EWD INTO NRN AL AND MIDDLE TN...
   WHILE THE PREVIOUS DAYS CONVECTION WILL LIKELY PLAY A ROLE IN
   DELINEATING THE PRECISE THREAT CORRIDOR...A SW-NE ORIENTED ZONE OF
   TRAINING SEVERE THUNDERSTORMS IS LIKELY FROM NERN LA ACROSS MS AND
   INTO NRN AL AND MIDDLE TN. THE STORMS WILL EITHER BE TIED TO THE
   COLD FRONT...OR AN OUTFLOW BOUNDARY WHICH COULD SPREAD OUT AHEAD OF
   THE MAIN SLOW MOVING FRONT. REGARDLESS...A VERY MOIST AND UNSTABLE
   AIR MASS WILL RESIDE AHEAD OF THE COLD FRONT...WITH SHEAR PROFILES
   QUITE FAVORABLE FOR SUPERCELLS AND TORNADOES. A LONG UPDRAFT
   RESIDENCE TIME IN THE UNSTABLE AND HIGHLY SHEARED ENVIRONMENT...AS
   WELL AS RELATIVELY STEEP MIDLEVEL LAPSE RATES SUGGEST STRONG
   TORNADOES WILL BE POSSIBLE. VERY LARGE HAIL WILL ALSO OCCUR AS WELL
   AS POTENTIAL FLOODING. THE MOST SIGNIFICANT TORNADO THREAT IS
   EXPECTED ACROSS MS.

   ...CNTRL AND NRN IL...FAR ERN IA AND NWRN IND...
   STRONG HEIGHT FALLS AND COOLING ALOFT WITH THE LEFT-EXIT REGION OF
   THE MIDLEVEL JET WILL OVERSPREAD THE WARM SECTOR...RESULTING IN
   RAPID DESTABILIZATION. WITH LITTLE CAPPING...A BROKEN ARC OF STORMS
   IS EXPECTED TO FORM BY EARLY AFTERNOON ALONG THE COLD FRONT. LARGE
   HAIL WILL BE LIKELY ALONG WITH A FEW TORNADOES.

   ...NRN SC INTO WRN AND CNTRL NC...
   AN E-W ORIENTED BOUNDARY WILL GRADUALLY MOVE NWD ACROSS NC...WITH
   MID 60S DEWPOINTS TO THE S. DAYTIME HEATING WILL ALLOW FOR
   DESTABILIZATION WITH AROUND 1000-1500 MLCAPE DEVELOPING BY
   AFTERNOON. WHILE SHORTWAVE RIDGING WILL EXIST MUCH OF THE
   DAY...COOLING ALOFT AND INCREASING SHEAR PROFILES WILL SPREAD INTO
   FAR WRN NC AND SC LATE IN THE DAY...RESULTING IN A FAVORABLE
   SUPERCELL ENVIRONMENT. HAIL WILL BE A DISTINCT THREAT WITH THE
   STRONGER CORES...BUT A TORNADO OR TWO WILL BE POSSIBLE AS LOW-LEVEL
   SHEAR INCREASES LATE IN THE DAY.

   ..JEWELL.. 04/27/2014

 

mBr4jxL.gif

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Sitting a little north of Joplin.  Waited for the outflow dominant storms to blow by and left a subtle outflow boundary just to the south.  Watching the new storms quickly popping in far northeast OK that should head this way.  They'll have clean air to work with and also some interaction with the outflow boundary.

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Man there is a lot of ongonig crapvection from eastern OK through much of Arkansas.  Stuff firing up again in NE OK and pushing up towards the Joplin area.

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Man there is a lot of ongonig crapvection from eastern OK through much of Arkansas.  Stuff firing up again in NE OK and pushing up towards the Joplin area.

 

Noticed this too, it really just does not want to clear out. Maybe behind SPC reasoning for staying at MDT.

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BULLETIN - EAS ACTIVATION REQUESTED  
TORNADO WARNING  
NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO  
1251 PM CDT SUN APR 27 2014  
 
THE NATIONAL WEATHER SERVICE IN PLEASANT HILL HAS ISSUED A  
 
* TORNADO WARNING FOR...  
SOUTHWESTERN CARROLL COUNTY IN NORTH CENTRAL MISSOURI...  
WESTERN LAFAYETTE COUNTY IN WEST CENTRAL MISSOURI...  
SOUTHEASTERN RAY COUNTY IN WEST CENTRAL MISSOURI...  
 
* UNTIL 115 PM CDT  
 
* AT 1248 PM CDT...A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A  
TORNADO WAS LOCATED NEAR ODESSA...AND MOVING NORTH AT 45 MPH.  
 
HAZARD...TORNADO AND GOLF BALL SIZE HAIL.  
 

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