MESOSCALE PRECIPITATION DISCUSSION 0611
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
618 AM EDT SAT AUG 27 2016
 
AREAS AFFECTED...EXTREME SOUTHEAST NV...FAR SOUTHWEST
UT...CENTRAL/NORTHERN AZ 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 271015Z - 271615Z
 
SUMMARY...SOME CONCENTRATED AREAS OF HEAVY RAINFALL ARE EXPECTED
THIS MORNING...ALONG WITH SOME THUNDERSTORMS. SOME RUNOFF AND/OR
FLASH FLOODING IS POSSIBLE.

DISCUSSION...A WELL-DEFINED SHORTWAVE TROUGH IS SEEN IN WV IMAGERY
CONTINUING TO DIG SOUTHEAST ACROSS SOUTH-CENTRAL CA AND IS
FACILITATING A DYNAMICALLY FAVORABLE ENVIRONMENT FOR SOME HEAVY
RAIN AND EMBEDDED STRONGER CONVECTIVE ELEMENTS OVER PORTIONS OF
SOUTHWEST UT AND ESPECIALLY NORTHERN AZ. THE FLOW PATTERN ALOFT IS
QUITE DIVERGENT AND FORCING CONTINUES TO INCREASE AS THE SHORTWAVE
TROUGH AMPLIFIES TOWARD THE REGION. THIS INCREASED LARGE SCALE
ASCENT REMAINS JUXTAPOSED WITH A POOL OF MODEST INSTABILITY OVER
THE REGION WITH MUCAPE VALUES OF UP TO 1000 J/KG...AND EVEN
GREATER INSTABILITY IS NOTED FARTHER SOUTH OVER CENTRAL AZ.

THE 00Z ARW/NMMB AND THE LATEST NCEP HRRR GUIDANCE SUGGESTS
ADDITIONAL CONCENTRATION OF LOCALLY HEAVY RAINFALL ACROSS PORTIONS
OF SOUTHWEST UT AND ESPECIALLY NORTHERN AZ THROUGH THE MORNING
HOURS AS SOME MID LEVEL DEFORMATION/COMMA-HEAD FORCING SETS UP.
SOME LOCALLY HEAVIER CONVECTIVE ELEMENTS ARE EXPECTED ALONG THE
INSTABILITY GRADIENT FARTHER SOUTH INVOLVING CENTRAL AZ.

EXPECT AS MUCH AS 1 TO 2 INCHES OF ADDITIONAL RAIN THROUGH LATE
MORNING...ESPECIALLY OVER SOME OF THE MORE OROGRAPHICALLY FAVORED
UPSLOPE AREAS. THIS MAY RESULT IN ADDITIONAL CONCERNS FOR RUNOFF
AND SOME FLASH FLOODING.

ORRISON

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

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

LAT...LON   37471289 37141154 36750965 35930915 34690943 
            34001065 33731188 33781304 34371438 35381498 
            36171520 36721494 37161444 37291405