MESOSCALE PRECIPITATION DISCUSSION 0701
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1253 AM EDT WED AUG 16 2017

AREAS AFFECTED...NEBRASKA

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

VALID 160445Z - 161000Z

SUMMARY...HEAVY SHOWERS AND THUNDERSTORMS WILL CONTINUE ACROSS A
LARGE PORTION OF NEBRASKA OVER THE NEXT SEVERAL HOURS. ADDITIONAL
FLASH FLOODING IS LIKELY.

DISCUSSION...NON-OPERATIONAL GOES-16 10.3 MICRON/IR IMAGERY SHOWS
AN IMPRESSIVELY COLD-TOPPED AND LARGE MCS EVOLVING ACROSS
NEBRASKA...WITH THE CONVECTION GRADUALLY SHIFTING OFF TO THE EAST
WITH TIME. THE ACTIVITY IS FOCUSING WITHIN AN INCREASINGLY
DIVERGENT UPPER AIR PATTERN OUT AHEAD OF A SHORTWAVE TROUGH
CROSSING THE CENTRAL ROCKIES. MEANWHILE...LOW PRESSURE OUT OVER
THE CENTRAL HIGH PLAINS IS ALLOWING FOR A SOUTHERLY LOW LEVEL JET
OF AS MUCH AS 30 TO 40 KTS TO TRANSPORT AN ABUNDANCE MOISTURE AND
INSTABILITY NORTHWARD THROUGH THE PLAINS AND OVER A W/E ORIENTED
STATIONARY FRONT SITUATED ACROSS SOUTHERN NEBRASKA.

MUCAPE VALUES OF AS MUCH AS 1500 TO 2000 J/KG ARE IN PLACE WITH A
NOSE OF 1.6 TO 1.8 INCH PWATS SURGING NORTH ACROSS
CENTRAL/SOUTHEAST KANSAS AND TOWARD SOUTHERN NEBRASKA WHERE THE
FRONT IS SITUATED. THIS ENERGY WILL FOSTER HEAVY RAINFALL AMOUNTS
OF AS MUCH AS 2 INCHES/HR OVERNIGHT.

THE HRRR GUIDANCE HAS BEEN TOO FAR NORTH WITH ITS CONVECTIVE
AXIS...BUT ADJUSTING FOR THE LATITUDINAL DISPLACEMENT...THE
ADDITIONAL RAINFALL AMOUNTS ARE FORECAST TO BE AS MUCH AS 3 TO 5
INCHES THROUGH ABOUT 10Z. THE HEAVIEST TOTALS SHOULD GENERALLY BE
ACROSS SOUTH-CENTRAL AREAS OF NEBRASKA AND BASICALLY JUST NORTH OF
THE AFOREMENTIONED FRONT. THESE RAINFALL AMOUNTS ARE LIKELY TO
CAUSE SOME ADDITIONAL FLASH FLOODING CONCERNS THROUGH THE NIGHT.

ORRISON

ATTN...WFO...GID...GLD...LBF...OAX...

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

LAT...LON   42279920 42189743 41939638 41449597 40979581
            40509605 40199676 40079814 40069931 40040020
            40130113 40430152 41200169 42060073