MESOSCALE PRECIPITATION DISCUSSION 0085
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
313 PM EDT TUE APR 03 2018

AREAS AFFECTED...ERN IL INTO IN...WRN AND NRN OHIO/WRN PA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 031912Z - 040110Z

SUMMARY...FLASH FLOODING IS EXPECTED FROM ERN IN...INTO MUCH OF
OHIO AND PERHAPS NWRN PA THROUGH 00Z WITH AN ADDITIONAL 1-3 INCHES
POSSIBLE ON TOP OF LOW FLASH FLOOD GUIDANCE. A SECONDARY CONCERN
FOR FLASH FLOODING EXISTS ACROSS ERN IL INTO WRN IN WHERE FLASH
FLOOD GUIDANCE IS ALSO LOW...ALTHOUGH STORMS SHOULD BE MORE
PROGRESSIVE TOWARD THE WEST.

DISCUSSION...ADDITIONAL TRAINING OF CONVECTION APPEARS LIKELY FROM
PORTIONS OF ERN IN INTO WRN AND NRN OHIO OVER THE NEXT 3 TO 6
HOURS. AS A WARM FRONT CONTINUES TO SLOWLY LIFT NORTH ACROSS THE
OHIO VALLEY AS OF 18Z...THINNING OF CLOUDS HAS ALLOWED FOR GREATER
SOLAR INSOLATION AND INCREASED MLCAPE NEAR THE SRN IN/OH BORDER.
INCREASES IN MUCAPE ARE ALSO ESTIMATED TO HAVE OCCURRED OVER NRN
OH...NORTH OF THE WARM FRONT WITH SUFFICIENT
INSTABILITY...500-1000+ J/KG...PRESENT ACROSS MUCH OF THE MPD
THREAT AREA...WITH THE EXCEPTION OF NWRN PA WHERE MUCAPE REMAINS
BELOW 100 J/KG. THIS DATA COMES FROM THE SPC MESOANALYSIS PAGE.

RADAR IMAGERY AS OF 1845Z SHOWED A SOUTHWEST TO NORTHEAST ORIENTED
AXIS OF CONVECTION MOVING THROUGH IN...LIKELY FOCUSED JUST AHEAD
OF A SUBTLE SHORTWAVE VISIBLE ON GOES-16 MID-LEVEL WATER VAPOR
IMAGERY. THIS REGION OF CONVECTION IS EXPECTED TO CONTINUE
EXPANDING BENEATH AN INCREASINGLY DIFFLUENT FLOW PATTERN
ALOFT...OUT AHEAD OF AN APPROACHING UPPER LEVEL TROUGH AXIS
CURRENTLY MOVING THROUGH THE NORTHERN PLAINS. THE ORIENTATION OF
THE WARM FRONT WILL ROUGHLY ALIGN WITH MEAN STORM MOTIONS OFF TO
THE EAST-NORTHEAST WITH UNIDIRECTIONAL FLOW ALOFT ALLOWING FOR THE
LIKELIHOOD OF TRAINING CONVECTION. AS THE CURRENT ROUND OF
CONVECTION MOVES FROM SRN IN INTO OH...ADDITIONAL CONVECTION WILL
BE POSSIBLE WITHIN AN UNSTABLE AIRMASS OVER SRN IN...IN ADVANCE OF
A COLD FRONT.

AHEAD OF THE COLD FRONT...CURRENTLY EXTENDING SOUTHWEST FROM A LOW
IN CNTRL IL...CONVECTION IS ANTICIPATED TO EXPAND THROUGH THE
EVENING WITH RAINFALL RATES OF 0.5 TO 1.0+ IN/HR. WHILE THESE
STORMS ARE EXPECTED TO STEADILY PROGRESS TO THE EAST WITH THE
MOVEMENT OF THE COLD FRONT...FLASH FLOOD GUIDANCE ACROSS PORTIONS
OF THIS REGION IS LESS THAN AN INCH IN 1 AND 3 HOURS...PROMPTING A
SHORT TERM CONCERN FOR FLASH FLOODING/RUNOFF.

GIVEN SATURATED SOILS AND EXPECTED TRAINING TO THE EAST...FLASH
FLOODING IS CONSIDERED LIKELY ACROSS BOTH REGIONS OF THE OHIO
VALLEY DESCRIBED ABOVE.

OTTO

ATTN...WFO...CLE...CTP...ILN...ILX...IND...IWX...LMK...LSX...
PBZ...RLX...

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

LAT...LON   41828008 41667940 41057954 40518135 39358299
            38708502 38558636 38778696 38668810 38778873
            39108907 39588879 39928808 40328683 40878548
            41338444 41618338 41608215 41798113