MESOSCALE PRECIPITATION DISCUSSION 0408
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
450 PM EDT SUN AUG 02 2015
 
AREAS AFFECTED...NORTHERN AZ...SOUTHERN AND CENTRAL UT 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 022045Z - 030245Z
 
SUMMARY...FLASH FLOODING IS LIKELY FROM INTENSE SHOWERS AND
THUNDERSTORMS EXPANDING OVER THE HIGHER TERRAIN.

DISCUSSION...CONVECTIVE CLOUD TOPS CONTINUE TO COOL OVER PORTIONS
OF NORTHERN AZ...CENTRAL AND SOUTHERN UT AS DIFFLUENT FLOW ALOFT
AHEAD OF A MID LEVEL SHORTWAVE TROUGH OVER THE SOUTHWEST COUPLES
WITH ANOMALOUS MOISTURE AND DIURNAL HEATING OVER THE REGION.

THE CIRA LAYERED PWAT PRODUCT SUGGEST A POOL OF ENHANCE MID AND
HIGH LEVEL MOISTURE OVER THE REGION WHICH WILL BE ENHANCING
RAINFALL EFFICIENCY AND RATES WITH THE INTENSE CONVECTIVE CORES
THAT DEVELOP THROUGH THE AFTERNOON AND EVENING HOURS. IN
FACT...THE PWATS AS PER THE 12Z GFS ARE PROGGED LATE TODAY TO BE
LOCALLY 2 TO 3 STANDARD DEVIATIONS ABOVE NORMAL OVER THE
REGION...AND THUS THE RAINFALL POTENTIAL WILL LOCALLY BE VERY HIGH.

CONSECUTIVE RUNS OF THE HRRR SUGGEST SOME OF THE MAIN FOCUS FOR
CONVECTIVE EXPANSION AND ORGANIZATION OCCURRING OVER NORTHERN AZ
AND UP ACROSS SOUTHERN/CENTRAL UT...WHERE THE LATEST EXPERIMENTAL
GLD LIGHTNING DENSITY PRODUCT INDICATES AN INCREASE IN STRIKE
INTENSITY. THE 12Z NAM-CONEST FAVORS RAINFALL AMOUNTS OF 2 TO 3
INCHES WITH LOCALLY HEAVIER TOTALS PERHAPS EXCEEDING 4 INCHES.
THIS APPEARS REASONABLE GIVEN THE DEEPER MOISTURE PROFILES OVER
THE REGION AND ESPECIALLY WITH OROGRAPHIC FOCUSING.

GIVEN THE SET-UP...FLASH FLOODING APPEARS LIKELY...AT LEAST
LOCALLY THROUGH THE EVENING HOURS.

ORRISON

ATTN...WFO...FGZ...GJT...SLC...VEF...

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

LAT...LON   40421043 39780996 38310973 36440992 35631021 
            34961073 34671159 34761245 35371291 36431296 
            38091271 39781214 40361156