MESOSCALE PRECIPITATION DISCUSSION 0317
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
654 PM EDT MON JUN 12 2017

AREAS AFFECTED...SERN WY/SWRN SD/WRN NE

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

VALID 122250Z - 130450Z

SUMMARY...A LOCAL THREAT FOR TRAINING HEAVY RAIN COULD POSE A
FLASH FLOOD THREAT LATE THIS EVENING ACROSS PORTIONS OF ERN WY
INTO SWRN SD AND THE WRN NE PANHANDLE. RATES OF 1.5 TO 2.5 INCHES
IN 1-2 HOURS ARE EXPECTED IN THE STRONGEST CORES.

DISCUSSION...REGIONAL RADAR AS OF 22Z OVER SERN WY INTO FAR NRN CO
SHOWED SEVERAL SUPERCELLS TRACKING NORTH TO NORTHEAST IN AN
UPSLOPE FLOW REGIME LOCATED NORTH OF A WAVY WARM FRONT. WHILE THE
CURRENT THREAT FROM THESE STORMS IS OF A SEVERE MODE...THERE ARE
CONCERNS FOR FLASH FLOODING TOWARD SUNSET AND BEYOND.

PRECIPITABLE WATER VALUES OVER SERN WY WERE NEAR 1 INCH WITH
VALUES APPROACHING AND EXCEEDING 1.5 INCHES TOWARD THE EAST OVER
SERN SD AS SEEN ON EXPERIMENTAL GOES 16 TPW IMAGERY AND RAP
ANALYSES. AS A LARGE CLOSED LOW CENTERED OVER THE NV/ID BORDER
CONTINUES TO ADVANCE EAST EARLY TONIGHT...INCREASING UPPER LEVEL
DIFFLUENCE WILL OVERSPREAD THE HIGH PLAINS AS THE NOCTURNAL LOW
LEVEL JET STRENGTHENS OVER WRN KS AND NE TO THE EAST OF A LOW NEAR
DEN FORECAST TO TRACK NEWD OVER THE NEXT 6-9 HOURS. THIS WILL
ALLOW ELY TO SELY LOW LEVEL MOISTURE TRANSPORT TO PUMP MOISTURE
WWD INTO THE HIGH PLAINS WHICH WHEN COMBINED WITH FAVORABLE UPPER
LEVEL SUPPORT SHOULD ALLOW FOR EXPANDING COVERAGE OF CONVECTIVE
ACTIVITY.

THE FLASH FLOOD THREAT MAY COME IN THE FORM OF TRAINING FROM SSW
TO NNE...ESPECIALLY IF ANY OUTFLOW BOUNDARIES ALIGN IN SUCH A WAY
TO ALLOW REPEATING STORM MOTIONS TOWARD THE NORTHEAST. IN
ADDITION...FLASH FLOOD GUIDANCE VALUES ARE 1-2 IN/HR AREA=WIDE AND
POCKETS OF LOWER FFG EXIST ON THE 3-HR TIMESCALE AS WELL. THIS
SCENARIO IS SUPPORTED THROUGH SIMULATED REFLECTIVITY SEEN IN
RECENT RUNS OF THE HRRR AND EXPERIMENTAL HRRR.

OTTO

ATTN...WFO...BOU...CYS...LBF...UNR...

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

LAT...LON   44680262 44550206 44230168 43820153 43420189
            42540288 41480359 40910411 40860465 41200512
            41990532 42530562 43040570 43740549 44180500
            44540413 44650346