MESOSCALE PRECIPITATION DISCUSSION 0224
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
758 PM EDT SUN AUG 25 2013
 
AREAS AFFECTED...SOUTHWEST UT...SOUTHERN NV...NORTHWEST
AZ...SOUTHEAST CA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 252358Z - 260130Z
 
SUMMARY...AN ONGOING FLASH FLOOD EVENT IS EXPECTED TO DECREASE IN
INTENSITY BETWEEN NOW AND 0130Z.  REGIONALLY, FLASH FLOODING IS
POSSIBLE UNTIL THAT TIME.

DISCUSSION...THUNDERSTORMS WITH HOURLY RAIN RATES IN THE RANGE OF
1-2 INCHES PER HOUR HAVE BEGUN A SLOW DECLINE ACROSS THE REGION,
AS AVAILABLE CAPE IS BEING SPENT BY ONGOING STORMS -- CURRENTLY
ESTIMATED BETWEEN 500-1000 J/KG -- AND LOW-LEVEL INFLOW INTO THE
REGION FROM THE GULF OF CALIFORNIA IS EXPECTED TO DECREASE
SHORTLY.  THE 23Z NSSL QPE INDICATES THAT OVER 9" OF RAIN MAY HAVE
FALLEN BETWEEN BULLHEAD CITY AZ AND TWENTYNINE PALMS CA OVER THE
PREVIOUS SIX HOURS. DIVERGENCE REMAINS EXCELLENT ACROSS THE REGION
TO THE SOUTHEAST OF AN UPPER LEVEL LOW MOVING ACROSS WESTERN OR. 
PRECIPITABLE WATER VALUES REMAIN STEADY IN THE 1.75-2.25 INCH
RANGE, ABOVE THE 90TH PERCENTILE FOR LATE AUGUST.  THE 21Z HRRR
RUN INDICATES THAT REMAINING THUNDERSTORM ACTIVITY SHOULD DIE
BETWEEN 01Z AND 02Z DUE TO FADING CAPE VALUES AND DECREASING LOW
LEVEL INFLOW, HENCE 0130Z BEING CHOSEN FOR A VALID TIME. 
CONFIDENCE IN EVENTS UNFOLDING IN THE ABOVE MANNER IS AVERAGE.

ROTH

ATTN...WFO...FGZ...SLC...PSR...VEF...SGX...

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

LAT...LON   36601287 35331363 34441444 33311574 32741642 32601671
            33461662 34101665 34991697 35121689 35201695 36061594
            36811546 37271423 37391279 36601287