MESOSCALE PRECIPITATION DISCUSSION 0450
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
339 PM EDT SAT JUL 14 2018

AREAS AFFECTED...EASTERN CA...CENTRAL/SOUTHERN NV...FAR SOUTHWEST
UT...FAR NORTHWEST AZ

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

VALID 141935Z - 150130Z

SUMMARY...SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY RAINFALL
WILL PROMOTE SOME FLASH FLOODING POTENTIAL.

DISCUSSION...THE LATEST GOES-16 CLEAN IR SATELLITE IMAGERY IS
SHOWING COOLING CONVECTIVE TOPS OVER AREAS OF THE CENTRAL
SIERRA-NEVADA AND EAST OVER A LARGE AREA OF CENTRAL/SOUTHERN NV.
PLENTY OF MONSOONAL MOISTURE REMAINS IN PLACE ACROSS THIS REGION
WITH PWATS AS MUCH AS 2 TO 3 STANDARD DEVIATIONS ABOVE NORMAL.
THIS MOISTURE IN CONJUNCTION WITH STRONG DIURNAL HEATING IS
RESULTING IN MLCAPE VALUES OF AS MUCH AS 1500 TO 2000+ J/KG...WITH
MUCH OF THE INSTABILITY NOTED OVER SOUTHERN NV.

SHOWERS AND THUNDERSTORMS WILL CONTINUE TO DEVELOP AND EXPAND IN
COVERAGE THIS AFTERNOON GIVEN THE MODERATE TO STRONGLY UNSTABLE
BOUNDARY LAYER...AND WITH A GENERAL TENDENCY TO BE OROGRAPHICALLY
FOCUSED. THERE IS ALSO PROXIMITY OF A WEAK MID LEVEL SHORTWAVE
TROUGH OVER CENTRAL AND EASTERN NV THAT IS DRIFTING TOWARD WESTERN
UT...AND THIS WILL PROMOTE SOME VERY MODEST FORCING ALOFT ALONG
WITH RELATIVELY STEEPER MID LEVEL LAPSE RATES FOR CONVECTIVE
GROWTH.

EXPECT RAINFALL RATES OF AS MUCH AS 1 TO 1.5 INCHES/HR WITH THE
STRONGER CONVECTIVE CORES AND THIS IS CONSISTENT WITH THE LATEST
HIRES CAM GUIDANCE. SOME FLASH FLOODING WILL BE POSSIBLE AS A
RESULT.

ORRISON

ATTN...WFO...HNX...LKN...REV...SLC...STO...VEF...

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

LAT...LON   39351773 39221663 39081536 39111400 38351345
            37381370 36581388 35601379 34961356 34541401
            34411460 34631520 35671595 36061666 36111736
            36211771 36151812 36521841 37101868 37581923
            38061967 38251975 38871966 39301854