MESOSCALE PRECIPITATION DISCUSSION 0027
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
602 PM EDT SUN APR 27 2014
 
AREAS AFFECTED...FAR SOUTHEAST OK...CENTRAL AND WESTERN
AR...CENTRAL AND SOUTHERN MO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 272155Z - 280300Z
 
SUMMARY...TRAINING AND BACK-BUILDING THUNDERSTORMS ALONG WITH A
FAVORABLE ENVIRONMENT FOR CELL MERGERS WILL ELEVATE THE RISK OF
FLASH FLOODING THROUGH THE EVENING HOURS. 

DISCUSSION...THE LATEST IR/VIS IMAGERY IS SHOWING THE EXPANSION
AND INCREASED ORGANIZATION OF SEVERE COLD-TOPPED THUNDERSTORMS
OVER SERN OK...FAR NERN TX AND THROUGH WRN/CNTRL AR. VIS IMAGERY
ALONE IS CONFIRMING THE ELIMINATION OF EARLY LOW TO MID LVL CIN AS
SEVERAL CLOUD STREETS ARE BECOMING APPARENT WHICH IS INDICATIVE OF
AN INCREASINGLY UNSTABLE BOUNDARY LAYER. THE CONVECTION IS
OCCURRING WITHIN A VERY UNSTABLE AIRMASS WITH MUCAPE VALUES
LOCALLY BETWEEN 3000 J/KG TO 4000 J/KG AS PER LATEST RAP ANALYSIS.
ALL THE WHILE THE MOISTURE AND INSTABILITY TRANSPORT IS BEING
AIDED BY A 50 KT SWLY LOW LVL JET.

OVER THE NEXT SEVERAL HOURS...THE CONVECTION WILL BE OF A HIGHLY
SEVERE MODE...HOWEVER...THE ENVIRONMENT IS BECOMING INCREASINGLY
FAVORABLE FOR CELL MERGERS AND WITH CONVECTION BECOMING ORIENTED
SW/NE AND MORE PARALLEL TO THE DEEPER LYR SWLY FLOW...THERE WILL
BE AN INCREASED THREAT FOR BACK-BUILDING AND TRAINING CONVECTION.
THIS SCENARIO IS HIGHLY SUGGESTED BY THE 12Z WRF-ARW/12Z WRF-NMM
AND THE 12Z NSSL WRF WITH SEVERAL SW/NE ORIENTED STRIPES OF HEAVY
TO EXCESSIVE RAINFALL INDICATED BY 00Z AND CONTINUING THROUGH THE
LATE EVENING HOURS.

GIVEN THAT SOME AREAS HAVE ALREADY SEEN LOCALLY HEAVY RAIN
TODAY...AND WITH THE RISK OF REPEATING AND TRAINING
CONVECTION...THERE WILL BE AN INCREASING THREAT FOR FLASH FLOODING
THROUGH THE EVENING HOURS. WILL CONTINUE TO MONITOR.

ORRISON

ATTN...WFO...PAH...MEG...LSX...LZK...SGF...SHV...EAX...TSA...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...

LAT...LON   36079147 35359184 34719237 34169304 33809386 33859482
            34049521 34549508 35209442 36049408 36879392 38219389
            38659280 38189148 37229113 36079147