MESOSCALE PRECIPITATION DISCUSSION 0199
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
123 AM EDT MON JUL 14 2014
 
AREAS AFFECTED...SOUTHEAST MO, SOUTHERN IL, WESTERN & CENTRAL KY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 140522Z - 141122Z
 
SUMMARY...A BAND OF THUNDERSTORMS IS TRYING TO FORM AHEAD OF AN
MCV WHICH IS EXPECTED TO SLOWLY EDGE SOUTHWARD AS THE CELLS
ATTEMPT TO TRAIN.  A FEW OCCURRENCES OF FLASH FLOODING ARE
POSSIBLE.

DISCUSSION...AN MCV HAS FORMED WITH A CONVECTIVE COMPLEX IN
MISSOURI AND A WARM ADVECTION BAND HAS FORMED JUST AHEAD OF IT,
EXTENDING INTO SOUTHERN IL.  RADAR INDICATES RAINFALL RATES
APPROACHING 2" AN HOUR WITHIN THIS SHORT BAND.  THE CONVECTIVE
ACTIVITY HAS FORMED NORTH OF A WEAK THERMAL BOUNDARY DUE TO CIN IN
ITS VICINITY, ACCORDING TO THE 00Z ARW.  PRECIPITABLE WATER VALUES
OF 2" ARE IN THE REGION, AND 25-30 KTS OF INFLOW AT 850 HPA IS
IMPORTING CAPES OF 1000-3000 J/KG FROM THE WARM SECTOR SOUTH OF
THE EFFECTIVE FRONTAL ZONE, WHICH CONTINUES DROPPING SLOWLY
SOUTHWARD INTO KY.

THE RAP AND ARW GUIDANCE INDICATE THAT THE BAND SHOULD CONTINUE
DROPPING SLOWLY SOUTHWARD WITH TIME.  THE MESOSCALE QPF OUTPUT HAS
INCREASED ITS AMOUNTS IN THIS AREA FROM THEIR 12Z AND 18Z RUNS,
SHOWING LOCAL 2-4" POSSIBLE AMONGST THE MORE RELIABLE GUIDANCE. 
DRY AIR IN THE 850-700 HPA LAYER OF AREA SOUNDINGS SHOULD CONTINUE
TO ALLOW FOR AN EAST TO EAST-SOUTHEAST MOTION OVERNIGHT FARTHER
INTO KY WITH TIME AS OUTFLOW BOUNDARIES FROM THE CONVECTION EDGE
IT FARTHER TO THE SOUTH WHILE CELLS POTENTIALLY TRAIN TO ITS
NORTH.  THIS COULD INCREASE THE INFLOW PROFILE ALONG THE BOUNDARY
AND MAGNIFY RAINFALL RATES SOMEWHAT WITH TIME.  FLASH FLOOD
GUIDANCE VALUES ARE RELATIVELY HIGH, IN THE 3-4" IN THREE HOUR
RANGE.  HOURLY RAIN RATES UP TO 2.5" AN HOUR WHERE CELLS TRAIN
WITH LOCAL AMOUNTS OF 2-4" COULD CAUSE A FEW INSTANCES OF FLASH
FLOODING.

ROTH

ATTN...WFO...JKL...LMK...PAH...LSX...

ATTN...RFC...LMRFC...NCRFC...OHRFC...

LAT...LON   37598347 36808550 37319054 38308991 38228597 37598347