MESOSCALE PRECIPITATION DISCUSSION 0472
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
313 PM EDT WED JUL 12 2017

AREAS AFFECTED...PORTIONS OF CENTRAL IN

CONCERNING...HEAVY RAINFALL

VALID 121912Z - 122312Z

SUMMARY...THUNDERSTORMS ARE BEGINNING TO SHOW A HINT OF TRAINING
CHARACTER AS THEY HEAD INTO AN AREA WITH PARTIALLY SATURATED
SOILS.  HOURLY RAIN RATES TO 2.5" WITH LOCAL AMOUNTS TO 4" ARE
POSSIBLE.

DISCUSSION...A WEAK WAVE ALONG AN OUTFLOW BOUNDARY IS BEGINNING TO
LEAD TO CONVECTION THAT IS EXHIBITING SOME TRAINING CHARACTER. 
PRECIPITABLE WATER VALUES ARE ~2". INFLOW AT 850 HPA IS CONVERGENT
AT ~25 KTS.  EFFECTIVE BULK SHEAR OF 20-30 KTS IS HELPING TO
ORGANIZE THE ACTIVITY INTO A SHORT BAND.  A SHORTWAVE SEEN ON
WATER VAPOR IMAGERY ACROSS SOUTH-CENTRAL WI IS AIDING DIVERGENCE
ALOFT.

THE MESOSCALE GUIDANCE THAT HAD A HINT OF THIS ACTIVITY -- RECENT
HRRR AND RAP RUNS AND THE 12Z WRF NSSL -- IS TOO FAR NORTH/TOO
SLOW WITH ITS SOUTHEAST PROGRESSION THUS FAR.  RAP RUNS DO
INDICATE A LITTLE MORE SOUTHEAST MOVEMENT TO THE THUNDERSTORM AREA
BASED ON ITS BOUNDARY LAYER MOISTURE CONVERGENCE FIELD, WHICH IS
SUPPORTED BY FORWARD PROPAGATING CONVECTIVE VECTORS AND THE
1000-500 HPA THICKNESS PATTERN ACROSS THIS REGION.  HOURLY RAIN
RATES UP TO 2.5" WITH LOCAL AMOUNTS UP TO 4" ARE POSSIBLE OVER AN
AREA WITH PARTIALLY SATURATED SOILS.  DUE TO THE UNCERTAINTY HERE,
USED A FOUR HOUR HORIZON.

ROTH

ATTN...WFO...ILN...ILX...IND...IWX...LOT...

ATTN...RFC...OHRFC...

LAT...LON   40788659 40648582 39908493 39008524 39208651
            39628723 39878741 40258758 40648719