MESOSCALE PRECIPITATION DISCUSSION 354
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
552 PM EDT SUN JUN 24 2018

AREAS AFFECTED...EASTERN NE...SOUTHEAST SD...SOUTHERN MN...WESTERN
IA

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

VALID 242152Z - 250252Z

SUMMARY...SLOW MOVING THUNDERSTORMS ARE INCREASING IN COVERAGE
LATE THIS AFTERNOON AND WILL CONTINUE INTO THE EVENING HOURS. 
FLASH FLOODING IS POSSIBLE IN THOSE AREAS THAT HAVE REPEATED
ROUNDS OF CONVECTION.

DISCUSSION...THE LATEST RADAR IMAGERY SHOWS THUNDERSTORMS RAPIDLY
DEVELOPING FROM NORTHEAST NEBRASKA TO CENTRAL IOWA AND SOUTHERN
MINNESOTA.  GOES 16 SATELLITE IMAGERY IS INDICATING COOLING CLOUD
TOPS WITH GOOD UPPER LEVEL DIVERGENCE, SUPPORTIVE OF STRONG
UPDRAFTS AND VERY HEAVY RAINFALL RATES POSSIBLY EXCEEDING TWO
INCHES PER HOUR AT TIMES.

A SLOW MOVING OCCLUDED LOW PRESSURE SYSTEM WITH A STATIONARY FRONT
STRETCHED ACROSS MUCH OF IOWA IS SERVING AS A FOCUSING MECHANISM,
ALONG WITH OUTFLOW BOUNDARIES FROM EARLIER CONVECTION ACROSS
KANSAS AND MISSOURI.  PWATS REMAIN HIGH WITH VALUES NEAR 1.75
INCHES ALONG WITH SURFACE BASED CAPE APPROACHING 3000 J/KG IN THE
WARM SECTOR. 

THE LATEST SUITE OF HIGH RES GUIDANCE IS INDICATING SCATTERED
AREAS OF 2 TO 4 INCH RAINFALL AMOUNTS BY 3Z WITH ISOLATED HIGHER
TOTALS POSSIBLE, WITH THE GREATEST PROSPECTS FOR THIS OVER
SOUTHWEST MINNESOTA AND NORTHWEST IOWA BASED ON THE MODEL
CONSENSUS.  THE GUIDANCE MAY BE UNDER FORECASTING THE AMOUNTS OVER
CENTRAL IOWA WHERE NEARLY STATIONARY STORMS HAVE FORMED ALONG THE
FRONT.  WITH FFG VALUES OF 1.5IN/3HR HAVING THE POTENTIAL TO BE
EXCEEDED, FLASH FLOODING IS POSSIBLE WITH THE HEAVIEST CONVECTION.

D. HAMRICK

ATTN...WFO...ABR...DMX...FSD...MPX...OAX...

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

LAT...LON   45249642 44989461 43999372 42499332 41459338
            40779386 40659491 40739610 41339691 42499743
            44239757