MESOSCALE PRECIPITATION DISCUSSION 0023
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
132 AM EDT FRI APR 03 2015
 
AREAS AFFECTED...LOWER TO MIDDLE OHIO RIVER VALLEY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 030531Z - 031130Z
 
SUMMARY...THE HEAVIEST RAINFALL OF THE NIGHT IS EXPECTED TO
DEVELOP OVER THE NEXT FEW HOURS ACROSS PORTIONS OF THE LOWER TO
MIDDLE OHIO VALLEY. TRAINING CELLS OF HEAVY RAINFALL SHOULD EXCEED
FLASH FLOOD GUIDANCE IN A FEW LOCATIONS SHOWING 1.5 TO 3 INCHES IN
3 HOURS.

DISCUSSION...RECENT RADAR TRENDS SHOWED INCREASING COVERAGE OF
CONVECTION ACROSS SRN ILLINOIS SPREADING ENEWD WITH THE MEAN WIND
OF ABOUT 40 KTS. 850-700 MB WINDS CURRENTLY MATCH OR EXCEED THE
MEAN WIND ACCORDING TO AREA WIDE VAD WIND PROFILE PLOTS AND
ELEVATED INSTABILITY OF 500 - 1500 J/KG REMAINS OVER SRN MISSOURI
INTO SRN ILLINOIS ACCORDING TO THE SPC MESOANALYSIS PAGE.

AS A SHORTWAVE CONTINUES ADVANCING EWD INTO THE CNTRL PLAINS THIS
MORNING...A STALLED FRONTAL BOUNDARY WILL REMAIN IN PLACE JUST
NORTH OF THE OHIO RIVER VALLEY INTO SRN MISSOURI...WHILE 850-700
MB FLOW CONTINUES TO PARALLEL THE MEAN WIND WITH TOTAL
PRECIPITABLE WATER VALUES OF 1.25 TO 1.5 INCHES. WHILE THESE
VALUES ARE ONLY MODESTLY ANOMALOUS...ENOUGH MOISTURE/INSTABILITY
APPEARS TO BE PRESENT TO PRODUCE HOURLY RAINFALL RATES OF 1 TO 1.5
IN/HR WITH WIND PROFILES SUPPORTIVE OF REPEATING CONVECTION. IN
ADDITION...DIFFLUENT UPPER LEVEL FLOW DIRECTLY OVER THE THREAT
AREA SHOULD HELP TO ENHANCE VERTICAL MOTIONS THROUGH ABOUT 12Z AT
WHICH POINT THE BETTER UPPER DIFFLUENCE IS PROGGED TO SHIFT EAST
WITH THE ADVANCING UPPER TROUGH OVER THE N-CNTRL CONUS. RECENT
HI-RES MODEL QPF SEEMS TO BE BROADLY HANDLING THE OVERALL
EVOLUTION OF CONVECTION PROPERLY...BUT IS FAILING TO CAPTURE THE
RECENT BURST OF NOCTURNAL CONVECTION NEAR AND NORTH OF THE
MISSOURI BOOTHEEL. THIS MAY LEAD TO A NWD BIAS IN HI-RES MODEL QPF
AS OUTFLOW IS LIKELY TO SHUNT PRECIPITATION TO THE SOUTH.

OTTO

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

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

LAT...LON   38598803 38598651 38538487 37788429 37248538 
            36918803 37118980 37609040 37959029 38338984