MESOSCALE PRECIPITATION DISCUSSION 0028
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
648 PM EDT SUN APR 27 2014
 
AREAS AFFECTED...CENTRAL AND EASTERN AR...CENTRAL AND SOUTHEAST
MO...WESTERN KY...WESTERN TN...NORTHERN MS...NORTHWEST AL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 272230Z - 280430Z
 
SUMMARY...SIGNIFICANT CONCERN FOR BACK-BUILDING AND TRAINING
CONVECTION THIS EVENING WHICH WILL DRIVE A SERIOUS RISK OF FLASH
FLOODING. ONGOING FLASH FLOODING CONCERNS WILL BE EXACERBATED BY
THIS.

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 ATTM.  THE
CONVECTION IS AGAIN 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. LATEST WV/GOES-RGB
IMAGERY ALSO SHOWS A STRONG UPPER LOW MOVING THROUGH WRN
KS...WHICH WILL BE PROVIDING STRONG DEEP LAYER ASCENT WITH VERY
DIFFLUENT FLOW OVER THE THREAT AREA THROUGH THE LATE EVENING...AND
AS A RESULT CONVECTION SHOULD CONTINUE TO ORGANIZE AND GRADUALLY
MERGE INTO WHAT WILL LIKELY BE MULTIPLE LINEARLY ORIENTED MCS
STRUCTURES.

OVER THE NEXT SEVERAL HOURS...WHILE THE CONVECTION WILL BE OF A
HIGHLY SEVERE MODE...THE ENVIRONMENT IS EXPECTED TO BECOME
INCREASINGLY FAVORABLE FOR CELL MERGERS AND WITH A LIKELIHOOD OF
BACK-BUILDING AND TRAINING CONVECTIVE LINE SEGMENTS. THIS SCENARIO
IS HIGHLY SUGGESTED BY THE 12Z WRF-ARW/12Z WRF-NMM AND THE 12Z
NSSL WRF WITH SEVERAL SW/NE ORIENTED BANDS OF TRAINING CONVECTION
PROGGED BY EACH OF THESE MODELS. MODEL OUTPUT SUPPORTS ADDITIONAL
RAINFALL AMTS IN THE 00Z TO 06Z TIME FRAME OF 3 TO 6 INCHES.
HOWEVER...GIVEN EXPECTED RAINFALL RATES OF 2 TO 3
INCHES/HR...ISOLATED HEAVIER AMTS OVER 6 INCHES WILL BE POSSIBLE.

THESE AMTS COULD CAUSE LIFE-THREATENING FLASH FLOODING GIVEN VERY
HEAVY RAINS EARLY AND NEARLY SATURATED SOIL. WILL CONTINUE TO
MONITOR.

ORRISON

ATTN...WFO...OHX...BMX...HUN...PAH...MEG...JAN...LSX...LZK...
SGF...

ATTN...RFC...ABRFC...LMRFC...MBRFC...NCRFC...OHRFC...SERFC...

LAT...LON   36838748 36258689 35368639 34658666 34298735 34038814
            34048910 34018970 33899077 33599231 33919292 34539249
            34859213 35469170 36269131 37209106 37749115 38359150
            38089024 37578887 37188802 36838748