MESOSCALE PRECIPITATION DISCUSSION 0514
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
755 PM EDT WED JUL 19 2017

AREAS AFFECTED...NORTHERN NE

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

VALID 192355Z - 200400Z

SUMMARY...SLOW-MOVING THUNDERSTORMS TENDING TO BACKBUILD OVER THE
SAME AREA WILL FOSTER SOME FLASH FLOODING THREAT OVER THE NEXT
COUPLE OF HOURS.

DISCUSSION...AN AXIS OF SLOW-MOVING AND BACKBUILDING THUNDERSTORMS
HAS DEVELOPED OVER MAINLY PARTS OF NORTHERN NE ALONG A
QUASI-STATIONARY FRONTAL ZONE. THE AIRMASS SOUTH OF THE FRONT IS
EXTREMELY UNSTABLE WITH OVER 4000 J/KG OF MLCAPE.
MEANWHILE...PWATS ARE RUNNING OVER 1.75 INCHES AND THIS COUPLED
WITH THE VIGOROUS UPDRAFT ACTIVITY INCLUDING MULTIPLE OVERSHOOTING
TOPS WILL FAVOR EXTREMELY HEAVY RAINFALL RATES OF UP TO OVER 2.5
INCHES/HR.

THE ACTIVITY SHOULD CONTINUE TO INTERACT WITH THE STRONG POOL OF
INSTABILITY OUT OVER THE CENTRAL PLAINS AND WITH THE AID OF A S/SW
LOW LEVEL JET OF 35 TO 40 KTS. SOME MODEST RIGHT-ENTRANCE REGION
JET DYNAMICS ALOFT WILL ALSO TEND TO ALLOW CONVECTION TO PERSIST
THROUGH THE EVENING HOURS WITH A DECENT LEVEL OF CONVECTIVE
ORGANIZATION AND A FAVORABLE SET-UP FOR BACKBUILDING CELLS.

THE HIRES MODEL GUIDANCE IS WAY UNDERDONE WITH THE RAINFALL
POTENTIAL ACROSS PARTS OF NORTHERN NEB BASED ON THE LATEST
SAT/RADAR TRENDS. EXPECT AS MUCH AS 3 TO 5 INCHES OF RAIN WITH
LOCALLY HEAVIER AMOUNTS THROUGH LATE EVENING. SOME FLASH FLOODING
WILL BE POSSIBLE AS A RESULT.

ORRISON

ATTN...WFO...FSD...LBF...OAX...

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

LAT...LON   42999905 42979785 42759713 42459695 41999722
            41889843 41919921 41960001 42100087 42340119
            42680112 42930030