MESOSCALE PRECIPITATION DISCUSSION 0697
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
251 PM EDT TUE AUG 15 2017
AREAS AFFECTED...NE NEBRASKA...SE SOUTH DAKOTA...NW IOWA
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 151847Z - 152247Z
SUMMARY...SLOW MOVING THUNDERSTORMS WITH VERY HEAVY RAINFALL HAVE
DEVELOPED OVER PARTS OF CENTRAL AND EASTERN NEBRASKA EARLY THIS
AFTERNOON, AND WILL LIKELY EXPAND IN COVERAGE OVER THE NEXT FEW
HOURS.
DISCUSSION...RADAR IMAGERY IS SHOWING A CONGEALING CLUSTER OF
INTENSE STORMS WITH RAINFALL RATES IN EXCESS OF 2 INCHES PER HOUR.
THIS IS IN ASSOCIATION WITH AN INCREASING WARM AIR ADVECTION
PATTERN FOCUSING OVER THE CENTRAL PLAINS AHEAD OF AN UPSTREAM
TROUGH OVER THE CENTRAL ROCKIES. THE LATEST EXPERIMENTAL GOES 16
IR IMAGERY IS INDICATING EXPANDING COLD CLOUD TOPS WITH THIS
CONVECTION, WITH RADAR ECHO TOPS OF 50KFT.
PWS ACROSS THE REGION ARE IN THE 1.5 TO 1.75 INCH RANGE. COMBINED
WITH MLCAPE OF 1500 TO 2500 J/KG JUST NORTH OF THE SURFACE FRONT,
THIS IS SUPPORTING THE VERY STRONG UPDRAFTS AND COLD TOPS AS SEEN
ON SATELLITE. THE CONVECTION SHOULD CONTINUE TO GENERALLY ADVANCE
SLOWLY TOWARDS THE NORTHEAST OVER THE NEXT FEW HOURS AND WILL
AFFECT PARTS OF SOUTHEAST SOUTH DAKOTA AND NORTHWEST IOWA.
EXPECT ADDITIONAL RAINFALL AMOUNTS OF AS MUCH AS 2 TO 4 INCHES
WITH ISOLATED HEAVIER TOTALS. THE LATEST HI-RES GUIDANCE IS
UNDERDONE WITH THE COVERAGE AND INTENSITY OF THE ONGOING
CONVECTION. WITH THIS AMOUNT OF RAINFALL FALLING ON SATURATED
GROUND FROM EARLIER RAIN, SOME RUNOFF AND/OR FLASH FLOODING
CONCERNS ARE POSSIBLE, WITH THE BIGGEST THREAT MAINLY OVER ANY
LOCAL URBAN CENTERS.
HAMRICK
ATTN...WFO...DMX...FSD...GID...LBF...OAX...
ATTN...RFC...MBRFC...NCRFC...
LAT...LON 43669635 43419530 42939492 42179510 41639568
41359650 41139709 40439812 40449911 40809976
41459979 42009973 42849919 43389820 43609723
Last Updated: 251 PM EDT TUE AUG 15 2017