MESOSCALE PRECIPITATION DISCUSSION 0181
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
836 PM EDT SAT JUL 27 2013
 
AREAS AFFECTED...SOUTHEAST NV...NORTHERN AZ...SOUTHERN UT 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 280030Z - 280300Z
 
SUMMARY...ADDITIONAL SHOWERS AND THUNDERSTORMS ARE EXPECTED OVER
THE NEXT 2 TO 3 HOURS WITH LOCALLY HVY SHORT-TERM RAINFALL RATES.
ADDITIONAL FLASH FLOODING IS POSSIBLE.

DISCUSSION...LATEST IR SAT IMAGERY SHOWS NUMEROUS CLUSTERS OF
COLD-TOPPED CONVECTION OVER SOUTHERN UT INVOF THE SOUTHERN WASATCH
MTN FRONT...AND ESP OVER NORTHERN AZ INVOF THE MOGOLLON RIM. ALL
OF THE CONVECTION IS IN RESPONSE TO A RELATIVELY DEEP POOL OF
MONSOONAL MOISTURE ALONG WITH DIURNALLY ENHANCED INSTABILITY
WORKING IN TANDEM WITH OROGRAPHICS. ADDITIONALLY...LATEST WV
IMAGERY SUGGESTS A WEAK SHORTWAVE IMPULSE OVER SERN NV ADVANCING
SLOWLY EASTWARD AROUND THE NWRN PERIPHERY OF THE LARGER SCALE
SUBTROPICAL RIDGE OVER THE FOUR CORNERS REGION. THIS IS LIKELY
PROVIDING AT LEAST SOME MODEST DYNAMICAL SUPPORT TO THE CONVECTION
OVER ESP SOUTHERN UT.

DIURNAL HEATING HAS BEEN MAXED OUT NOW OVER THE THREAT AREA...BUT
LATEST RAP ANALYSIS SHOWS AN INSTABILITY AXIS ASSOCD WITH A SRLY
LOW TO MID LVL FEED OF MONSOONAL MOISTURE STRETCHING FROM SOUTHERN
AZ UP INTO EXTREME SERN NV AND SOUTHERN UT. THIS WILL COUPLE WITH
THE AFOREMENTIONED SHORTWAVE ENERGY AND OROGRAPHICS TO SUPPORT A
CONTINUATION OF SMALL-SCALE CLUSTERS OF CONVECTION OVER THE NEXT 2
TO 3 HOURS WITH THE ACTIVITY THEN EXPECTED TO WEAKEN. GIVEN
SHORT-TERM RAINFALL RATES OF LOCALLY OVER 1 INCH/HR...SOME
ADDITIONAL FLASH FLOODING IS POSSIBLE.


ORRISON

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

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

LAT...LON   38631095 38020980 37260930 36390933 35900984 35381042
            34911140 34581234 34531365 34911448 35511483 36151484
            36681445 37621422 38301322 38651190 38631095