MESOSCALE PRECIPITATION DISCUSSION 0556
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
941 PM EDT MON JUL 24 2017

AREAS AFFECTED...SW UTAH...NW ARIZONA...S NEVADA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 250141Z - 250541Z

SUMMARY...CLUSTERS OF SLOW MOVING THUNDERSTORMS ARE EXPECTED LATE
THIS EVENING OVER PARTS OF SOUTHERN NEVADA, SOUTHWEST UTAH, AND
NORTHWEST ARIZONA.  HOURLY RAINFALL RATES ON THE ORDER OF 1 TO 1.5
INCHES PER HOUR MAY LEAD TO SOME LOCALIZED FLOODING PROBLEMS.

DISCUSSION...THE LATEST GOES-16 INFRARED IMAGERY IS DEPICTING
SUSTAINED CONVECTION AND WIDESPREAD COLD CLOUD TOPS ACROSS WESTERN
UTAH AND EAST CENTRAL NEVADA.  SLOW MOVING STORMS CURRENTLY
ONGOING ARE SLOWLY BACKBUILDING TOWARDS THE SOUTH.  UPPER LEVEL
PARAMETERS, INCLUDING RIGHT ENTRANCE JET DYNAMICS AND A WELL
DEFINED MID-LEVEL TROUGH OVER NORTHERN CALIFORNIA, ARE PROVIDING
AN ENVIRONMENT FAVORABLE FOR LARGE SCALE ASCENT OVER THIS REGION
AND WILL SUPPORT AND MAINTAIN UPDRAFT STRENGTH. PW VALUES
AVERAGING NEAR 1.5 INCHES ARE LIKELY THROUGH THE EVENING HOURS
BASED ON THE LATEST RAP ANALYSIS, ALONG WITH MLCAPE ON THE ORDER
OF 1500 TO 2500 J/KG.  

THE LATEST HI-RES MODEL GUIDANCE, INCLUDING THE HRRR, IS
SUGGESTING THE POSSIBILITY OF 1 TO LOCALLY 3 INCHES OF RAINFALL,
WITH THE BEST POTENTIAL FOR THIS NEAR THE NEVADA/UTAH BORDER. 
GIVEN RECENT DOPPLER RADAR TRENDS, THE POTENTIAL EXISTS FOR
ISOLATED 2 INCH AMOUNTS THROUGH 5Z.  THE THREAT OF FLASH FLOODING
IS GREATEST FOR ARROYOS AND CANYON AREAS.

HAMRICK

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

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

LAT...LON   38681221 38221089 37351063 36541081 35911166
            35731322 35801503 36761612 37781626 38451540
            38671386