MESOSCALE PRECIPITATION DISCUSSION 0028
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
144 PM EDT TUE APR 07 2015
 
AREAS AFFECTED...EASTERN MO...SOUTHERN IL...SOUTHERN IN...FAR
NORTHWEST KY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 071740Z - 072200Z
 
SUMMARY...A SLOW-MOVING MCS WILL CONTINUE TO FAVOR FLASH FLOODING
OVER THE NEXT SEVERAL HOURS AS IT APPROACHES THE LOWER OH VALLEY.

DISCUSSION...THE LATEST IR SAT IMAGERY SHOWS VERY COLD-TOPPED
CONVECTION ASSOCIATED WITH AN MCS ALONG WITH OCCASIONAL
OVERSHOOTING TOPS CONTINUING TO IMPACT PORTIONS OF SOUTHEASTERN MO
AND SOUTHERN IL. THE ACTIVITY IS ATTEMPTING TO BUILD EASTWARD INTO
SOUTHERN IN AT THIS TIME ALONG THE EASTERN END OF WHAT IS
ESSENTIALLY A DIFFERENTIAL HEATING BOUNDARY. 

THE CONVECTION CONTINUES TO FOCUS A LOW LEVEL COLD POOL WHICH IS
BEING INTERCEPTED BY A WELL-DEFINED AND BROAD LOW LEVEL WARM AIR
ADVECTION REGIME THAT IS CHARACTERIZED BY PWATS OF 1.4 TO 1.5
INCHES AND MUCAPE VALUES NEAR 2000 J/KG. AN UPTICK IN DIURNAL
HEATING SHOULD FOCUS STRONGER SURFACE-BASED INSTABILITY THROUGH
THE AFTERNOON HOURS NEAR THE SOUTHERN FLANK OF THE MCS INVOLVING
SOUTHEAST MO...SOUTHERN IL AND SOUTHERN IN. THIS COUPLED WITH SOME
LARGER SCALE DIVERGENT FLOW ALOFT SHOULD HELP SUSTAIN AND EVEN
LOCALLY ENHANCE THE ONGOING CONVECTIVE ACTIVITY AS IT PUSHES
GRADUALLY EAST. GOES-RGB SAT IMAGERY ALSO SHOWS A RIBBON OF DRIER
MID LEVEL AIR ASSOCIATED WITH SOME WEAK VORT ENERGY AND THIS WILL
PROVIDE FOR ADDITIONAL CONVECTIVE SUPPORT.

THE GLOBAL MODELS ARE NOT HANDLING THE ONGOING ACTIVITY WELL AT
ALL...WITH THE BEST GUIDANCE GENERALLY BEING THE LATEST HRRR. THIS
COUPLED WITH THE 12Z GEM-REGIONAL AND 12Z WRF-ARW/NMMB SOLUTIONS
FAVOR AN ADDITIONAL 1 TO 3 INCHES OF RAIN ALONG THE PATH OF THE
MCS...BUT THE REPEAT AND BACK-BUILDING NATURE OF THE CONVECTION
WILL SUPPORT LOCALLY HEAVIER AMOUNTS THAN THIS THAT COULD APPROACH
5 INCHES. FLASH FLOODING WILL BE LIKELY OVER THE NEXT FEW HOURS
NEAR THE PATH OF THE MCS.

ORRISON

ATTN...WFO...ILN...ILX...IND...LMK...LSX...PAH...SGF...

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

LAT...LON   39308647 38978517 38338534 37748659 37468783 
            37368848 37338994 37529123 37969180 38609144 
            38738928 38998792