MESOSCALE PRECIPITATION DISCUSSION 0195
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
831 PM EDT THU MAY 24 2018

AREAS AFFECTED......SIERRA NEVADA INTO WESTERN NEVADA...

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

VALID 250030Z - 250430Z

SUMMARY...CONVECTION EXPANDING WITHIN A DIFLUENT UPPER FLOW
PATTERN ACROSS THE EASTERN SIERRA NEVADA AND WESTERN NEVADA WILL
LEAD TO HOURLY RAINFALL RATES NEAR OR ABOVE 0.75" UNDER THE
STRONGEST CORES. GIVEN THE CURRENT FLASH FLOOD GUIDANCE,
ESPECIALLY OVER BURN SCARS, THIS WILL POSE A FLASH FLOOD THREAT
THROUGH 04Z.

DISCUSSION...A FAVORABLE SYNOPTIC PATTERN EAST OF A CLOSED-UPPER
LOW OFF THE CALIFORNIA COAST, MARKED BY STRONG UPPER DIFLUENCE AND
UPSLOPE LOW-LEVEL FLOW ALONG THE EASTERN SLOPES OF THE SIERRA
NEVADA, IN COMBINATION WITH ROBUST AVAILABLE INSTABILITY (MUCAPES
AROUND 1000 J/KG) AND ABOVE NORMAL PW VALUES (BETWEEN 0.50-0.75")
WILL RESULT IN AN ENHANCED FLASH FLOOD THREAT THROUGH THIS EVENING
ALONG THE EASTERN SLOPES OF THE SIERRA INTO WESTERN NV.

IN TERMS OF THE LATEST HIGH-RES CAM GUIDANCE, THE LATEST HRRR AND
EXPERIMENTAL HRRR RUNS CONTINUE TO SUPPORT POCKETS OF HOURLY
RAINFALL RATES UP TO 0.75-1.0"/HR UNDERNEATH THE STRONGEST CORES.
GIVEN THE CURRENT FLASH FLOOD GUIDANCE, PARTICULARLY OVER BURN
SCARS, THIS WILL ENHANCE THE FLASH FLOOD THREAT THROUGH 04Z.

HURLEY

ATTN...WFO...REV...STO...

ATTN...RFC...CNRFC...

LAT...LON   40902122 40692046 40101971 39571926 38731885
            38101880 37981922 38401976 39192030 39692067
            40092098 40652158