MESOSCALE PRECIPITATION DISCUSSION 0300
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
742 AM EDT THU JUN 14 2018

AREAS AFFECTED...NORTHWEST IOWA TO CENTRAL IA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 141141Z - 141356Z

SUMMARY...CELLS PRODUCING HEAVY RAINFALL WERE BECOMING MORE
NUMEROUS OVER PORTIONS OF NORTHWESTERN IA AND CENTRAL IA. 
RAINFALL RATES APPROACHING 1.5 INCHES PER HOUR HAVE BEEN INDICATED
ON AREA RADARS...WHICH WAS APPROACHING 1 HOURLY FLASH FLOOD
GUIDANCE. THIS WAS SETTING UP THE POSSIBILITY OF FLASH FLOODING.

DISCUSSION...SATELLITE IMAGERY WAS SHOWING AN AREA OF COOLING
CLOUD TOPS OVER IA IN A REGION WHERE A POOL OF PRECIPITABLE WATER
VALUES WERE IN EXCESS OF 1.5 INCHES AND WHERE H85 FLOW ON THE
ORDER OF 40 KTS WAS ABLE TO TAP MIXED LAYER CAPES OF AROUND 1500 J
PER KG.  THE RESULT WAS THAT SHOWERS AND THUNDERSTORMS CAPABLE
WERE DEVELOPING ACROSS PARTS OF NORTHWESTERN IA SOUTHEASTWARD
TOWARDS THE CENTRAL PART OF THE STATE. IN PARTICULAR...RECENT
GOES-16 IR IMAGERY HAS SHOWN A BACKBUILDING SIGNATURE JUST EAST OF
THE KFSD RADAR. THIS IS OCCURRING VERY NEAR AN MCV WHICH HAS
REMAINED NEARLY STATIONARY. AS SUCH...THIS MAY PROVIDE A FOCUS FOR
LOCALIZED FLASH FLOODING ISSUES. WEATHER UNDERGROUND SITES HAVE
SHOWN 2 TO 2.50 INCHES OF RAINFALL SINCE MIDNIGHT ACROSS
NORTHWESTERN IA WITH PRECIPITATION CONTINUING TO FALL.

FLASH FLOOD GUIDANCE IN THIS AREA WAS GENERALLY 1.50 TO 1.75
INCHES.  THUS FLASH FLOODING IS POSSIBLE...ESPECIALLY IN AREAS
WHICH RECEIVE MULTIPLE ROUNDS OF CONVECTION. 

THE RAP AND HRRR SEEM TO BE HANDLING THE CONVECTION WELL.  THESE
MODELS LIFT THE ENTIRE AREA NORTHEAST THROUGH 14Z BEFORE RAINFALL
RATES TAPER OFF IN RESPONSE TO THE INFLOW OF MOISTURE AND
INSTABILITY IS DISRUPTED.

BANN/RUBIN-OSTER

ATTN...WFO...DMX...FSD...

ATTN...RFC...MBRFC...NCRFC...

LAT...LON   43729599 43619568 43459544 43329511 43049464
            42849379 42389358 42199377 42209425 42499501
            42649528 42959575 43229628 43449643 43669634