MESOSCALE PRECIPITATION DISCUSSION 0632
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
701 PM EDT SAT AUG 05 2017
AREAS AFFECTED...CENTRAL/SOUTHEAST NV...SOUTHERN UT...FAR
SOUTHWEST CO
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 052300Z - 060300Z
SUMMARY...CLUSTERS OF SLOW-MOVING THUNDERSTORMS WITH HEAVY RAIN
WILL CONTINUE THROUGH THE EARLY EVENING HOURS. SOME FLASH FLOODING
IS POSSIBLE.
DISCUSSION...SATELLITE AND RADAR TRENDS HAVE BEEN SHOWING A
GRADUAL INCREASE IN CONVECTIVE COVERAGE OVER THE LAST COUPLE OF
HOURS OVER AREAS OF CENTRAL/SOUTHEAST NV AND EAST ACROSS SOUTHERN
UT AND INTO SOUTHWEST CO. THE CONVECTION HAS BEEN GENERALLY
DEVELOPING ALONG WITH A WELL-DEFINED MOISTURE GRADIENT WITH THE
AID OF STRONG DIURNAL HEATING AND LOCAL OROGRAPHIC FORCING.
PWATS OVER THE REGION ARE GREATEST FARTHER SOUTH AND CLOSE TO THE
AZ/UT BORDER AND ADJACENT AREAS OF FAR SOUTHEAST NV WHERE THEY ARE
BETWEEN 1.25 AND 1.5 INCHES. THE VALUES THOUGH ARE HIGH ENOUGH
ACROSS THE CONVECTIVE INITIATION ZONE FARTHER NORTH TO FAVOR
AMOUNTS THAT COULD REACH 1.5 INCHES IN AN HOUR WHICH IS LIKELY TO
CAUSE SOME CONCERNS FOR LOCALLY ENHANCED RUNOFF PROBLEMS.
OVER THE NEXT FEW HOURS...THE CONVECTION WILL TEND TO EXPAND A BIT
FURTHER IN COVERAGE...WITH THE HRRR GUIDANCE FAVORING SOME
ORGANIZED SMALLER SCALE CLUSTERS OF CONVECTION OVER PARTS OF
SOUTHEAST NV AND SOUTHERN UT IN PARTICULAR GOING INTO THE EARLY
EVENING HOURS AS THE CONVECTION WILL TEND TO PRODUCE CLASHING
OUTFLOW BOUNDARIES AND POSSIBLE CELL-MERGERS...AND WILL ALSO BE IN
AN ENVIRONMENT OF FAVORABLE BOUNDARY LAYER MOISTURE AND
INSTABILITY...ALONG WITH A WEAK DEFORMATION ZONE ALOFT FOR SOME
MODEST ASCENT.
EXPECT RAINFALL AMOUNTS TO PERHAPS REACH AS MUCH AS 2 TO 3 INCHES
THROUGH 03Z. SOME FLASH FLOODING IS POSSIBLE AS A RESULT.
ORRISON
ATTN...WFO...ABQ...FGZ...GJT...LKN...SLC...VEF...
ATTN...RFC...CBRFC...CNRFC...
LAT...LON 39371581 39161440 38871308 38961162 38841060
38650956 38260810 37440777 36920834 36970939
37031060 37031165 36991206 37001264 37031350
37271481 37201615 37761703 38521735 39191710
Last Updated: 701 PM EDT SAT AUG 05 2017