MESOSCALE PRECIPITATION DISCUSSION 0115
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1030 PM EDT MON APR 30 2018

AREAS AFFECTED...CNTRL/NERN NE INTO EXTREME SERN SD

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

VALID 010226Z - 010700Z

SUMMARY...LOCALIZED FLASH FLOODING WILL BE POSSIBLE OVER THE NEXT
FEW HOURS OVER PARTS OF CNTRL TO NERN NE AND EXTREME SERN SD.
RAINFALL RATES OF 1-2 IN/HR WITH TRAINING CAN BE EXPECTED.

DISCUSSION...KLNX RADAR REFLECTIVITY SHOWED TRAINING/REGENERATION
OF HEAVY RAIN ALONG THE SOUTHERN FLANK OF A SW TO NE ORIENTED AXIS
OF CONVECTION LOCATED OVER NERN NE. THE PORTION OF THIS AXIS ALONG
THE SD/NE BORDER WAS SLOWLY MOVING EAST BUT THE SRN FLANK WAS
STALLED BETWEEN BBW AND ODX AS OF 02Z. EARLIER RAINFALL RATES FROM
BROKEN BOW SHOWED 0.5 INCHES OF RAIN IN 20 MINUTES ENDING AT
0113Z...AND DESPITE SOME POSSIBLE EMBEDDED HAIL...HEAVY RAINFALL
WITH RATES OF 1-2 IN/HR IS LIKELY OCCURRING OVER EASTERN
CUSTER/WESTERN VALLEY COUNTY.

SHORT TERM FORECASTS FROM THE RAP SHOW LITTLE MOVEMENT OF THE COLD
FRONT OVER NEBRASKA THROUGH 09Z AND THIS WILL KEEP AN ONGOING
50-60 KT LOW LEVEL JET FOCUSED INTO A LOCAL OUTFLOW BOUNDARY
LOCATED JUST SOUTH OF THE ONGOING CONVECTION. DIVERGENCE ALOFT IS
ALSO EXPECTED WITHIN THE RIGHT ENTRANCE REGION OF A 70-90 KT
LOCATED AT 250 MB OVER THE DAKOTAS. LOW LEVEL INFLOW WILL BE
ALIGNED WITH MEAN STORM MOTIONS OFF TO THE NORTHEAST AT 30-40
KT...ALLOWING TRAINING OF CELLS. VEERING OF THE LOW LEVEL FLOW IS
EXPECTED BEYOND 06Z WHICH SHOULD END THE FLASH FLOOD THREAT. WHILE
THE NRN END OF THE CONVECTIVE CLUSTER IS EXPECTED TO MOVE OFF
TOWARD THE EAST...CONTINUED OVERRUNNING FROM THE SOUTH MAY EXTEND
THE FLASH FLOOD RISK OVER NERN NE IN THE NEXT FEW HOURS. SOME OF
THE EXPECTED FLASH FLOOD ISSUES WILL FALL JUST OUTSIDE OF THE
HIGHER FLASH FLOOD GUIDANCE COINCIDENT WITH THE SAND HILLS OF
CNTRL NE.

OTTO

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

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

LAT...LON   43249636 43019611 42499647 41739778 41279893
            41399959 41809962 42309910 42849766 43189679