MESOSCALE PRECIPITATION DISCUSSION 0513
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
534 PM EDT WED JUL 19 2017

AREAS AFFECTED...FAR EASTERN CA...FAR SOUTHEAST NV...AZ

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 192130Z - 200330Z

SUMMARY...MONSOONAL SHOWERS AND THUNDERSTORMS WILL CONTINUE WELL
INTO THE EVENING HOURS. SOME FLASH FLOODING IS EXPECTED.

DISCUSSION...CLUSTERS OF THUNDERSTORMS CONTINUE TO DEVELOP AND
EXPAND IN COVERAGE OVER MUCH OF CENTRAL AND WESTERN AZ IN RESPONSE
TO STRONG DIURNAL HEATING AND PLENTY OF DEEPER LAYER MOISTURE.
PWATS CONTINUE RUN GENERALLY IN THE 1.7 TO 1.9 INCH RANGE...WITH A
BIT MORE DRY AIR NOW SEEN FARTHER EAST ATTEMPTING TO ADVECT WEST.

EXPECT NUMEROUS SHOWERS AND THUNDERSTORMS THROUGH THE REMAINDER OF
THE AFTERNOON AND INTO THE EVENING HOURS AS STRONG DIURNAL
HEATING/SURFACE-BASED INSTABILITY...DEEPER MOISTURE AND
OROGRAPHICS ALL WORK IN TANDEM TO PROMOTE FAIRLY WIDESPREAD
CONVECTIVE COVERAGE. RAINFALL RATES OF UP TO 2.5 INCHES/HR ARE
GOING TO BE POSSIBLE THROUGH THE PERIOD GIVEN THE LEVEL OF DEEPER
MOISTURE WHICH THE LATEST CIRA-LPW PRODUCT AS OF 18Z CONFIRMS. THE
NOTABLE CONCENTRATION OF MOISTURE IN THE 500/300 MB LAYER WILL
PROMOTE HIGHLY EFFICIENT RAINFALL PROCESSES FOR ENHANCED RAINFALL
RATES.

EXPECT ADDITIONAL RAINFALL AMOUNTS THIS PERIOD OF AS MUCH AS 3 TO
4 INCHES...AND THIS IS LIKELY GOING TO CAUSE MORE FLASH FLOODING
AT LEAST LOCALLY AND ESPECIALLY IN VICINITY OF AREA DRY
WASHES/ARROYOS AND WHERE STEEPER TERRAIN WILL ENHANCE RUNOFF
THROUGH DOWNSTREAM CANYON AREAS.

ORRISON

ATTN...WFO...FGZ...PSR...SLC...TWC...VEF...

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

LAT...LON   37071267 36881168 36241131 35301113 34021008
            32880924 31660954 31381101 32061320 32651416
            33501495 34661531 35491541 36261517 36911403