MESOSCALE PRECIPITATION DISCUSSION 0148
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
950 PM EDT MON JUN 23 2014
 
AREAS AFFECTED...SERN MISSOURI INTO CNTRL AND SWRN ILLINOIS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 240148Z - 240648Z
 
SUMMARY...THE FLASH FLOOD THREAT IS INCREASING FROM SERN MISSOURI
TO CNTRL ILLINOIS INTO THE MIDDLE OF THE NIGHT WITH THE APPROACH
OF A LOW-MID LEVEL MESOSCALE WAVE INTO A REGION OF DEEP MOISTURE
AND TALL/SKINNY CAPES. 

DISCUSSION...WHILE THE ENTIRE REGION IS CHARACTERIZED BY WEAK
TROPOSPHERIC FLOW...LESS THAN OR EQUAL TO 30 KTS...DEEP MOISTURE
IS PRESENT FROM NRN ARKANSAS INTO SERN MISSOURI AND SRN ILLINOIS
AS SEEN BY 2+ INCH PRECIPITABLE WATER VALUES ON THE BLENDED TPW
PRODUCT. A LARGE PORTION OF THE THREAT AREA HAS NOT SEEN
CONVECTION DURING THE AFTERNOON HOURS BUT IS STARTING TO FILL IN
AS 500 TO 1500 J/KG OF UNTAPPED INSTABILITY IS UTILIZED WITH THE
APPROACH OF A MESOSCALE WAVE NOTED BETWEEN 700 AND 500 MB OVER
NWRN ARKANSAS. 

THIS WAVE IS FORECAST TO SLOWLY MOVE EAST TONIGHT...WITH ROUGHLY
30 KTS FORECAST FROM THE SSW AT 850 MB WHICH PARALLELS THE MEAN
FLOW OF THE CLOUD BEARING LAYER. A DEFORMATION AXIS ASSOCIATED
WITH THE SHORTWAVE APPEARS TO SET UP FROM SERN MISSOURI INTO SRN
ILLINOIS WITH SLOW MOVEMENT OR TRAINING OF HEAVY RAIN ECHOES
LIKELY. GIVEN EARLIER DAYTIME CONVECTION WAS REPORTED TO EXHIBIT
INSTANTANEOUS RAINFALL RATES OF 3 IN/HR...THE ENVIRONMENT
CONTINUES TO SHOW THE POTENTIAL FOR HEAVY RAINFALL WITH FLASH
FLOODING POSSIBLE GIVEN THE CURRENT FFG VALUES OF 1-2 IN/HR AND
2-3 IN/3 HR. A MAJORITY OF THE HI-RES MODELS HAVE BEEN HINTING AT
THIS SCENARIO UNFOLDING BUT HAVE DIFFERED IN LOCATION AND TIMING.
GIVEN CURRENT OBSERVATIONS...CONFIDENCE IS HIGH ENOUGH TO
HIGHLIGHT THIS REGION THROUGH AT LEAST 0600 UTC AT WHICH POINT THE
ENVIRONMENT CAN REASSESSED AND UPDATED IF NEEDED.  

OTTO

ATTN...WFO...PAH...ILX...MEG...LSX...LZK...SGF...

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

LAT...LON   36459247 37309228 38809125 39759020 40208894 39998827
            39298805 37928882 37148968 36199139 36459247 
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