MESOSCALE PRECIPITATION DISCUSSION 0507
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
725 PM EDT SAT JUL 30 2016
 
AREAS AFFECTED...SRN NV INTO SRN UT/NRN AZ 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 302322Z - 310330Z
 
SUMMARY...EXPECTED INCREASING COVERAGE OF CONVECTION OVER THE NEXT
FEW HOURS FROM SRN NV...NRN AZ INTO SRN UT MAY LEAD TO A FLASH
FLOOD THREAT. RAINFALL RATES OF 1-2 IN/HR ALONG WITH LOCALIZED
TRAINING CAN BE EXPECTED THROUGH 03Z.

DISCUSSION...SCATTERED THUNDERSTORMS WERE ONGOING AS OF 23Z ACROSS
PORTIONS OF SWRN UT...NRN AZ AND SRN NV. OBSERVED STORM MOTIONS
HAVE BEEN RATHER SLOW...10 KTS OR LESS...JUST NORTH OF A 850-400
MB MEAN LAYER RIDGE CENTERED IN CNTRL ARIZONA. THE COVERAGE OF
CONVECTION HAS BEEN 
RATHER SCATTERED UP TO THIS POINT...WITHIN AN INSTABILITY AXIS OF
500-1500 J/KG AS SEEN ON THE SPC MESOANALYSIS PAGE AS OF 23Z.
PRECIPITABLE WATER VALUES ARE ESTIMATED TO BE 1.0 TO 1.3 INCHES
WHICH WOULD PLACE STANDARDIZED ANOMALIES IN THE +1 TO +2 RANGE. 

AN SLIGHT INCREASE IN THUNDERSTORM COVERAGE IS EXPECTED AS CELL
AND OUTFLOW MERGERS SPARK NEW DEVELOPMENT WITHIN THE INSTABILITY
AXIS...ESPECIALLY WITH ACTIVITY APPROACHING FROM ERN NEVADA. A
CORRIDOR OF 15-20 KTS OF 850-700 MB MEAN FLOW IS FORECAST BY THE
RAP TO DEVELOP ALONG THE UT/AZ BORDER IN THE 00-03Z TIME
FRAME...WHICH WOULD EXCEED MEAN-STORM MOTIONS. GIVEN THE
UNIDIRECTIONAL FLOW IN PLACE...THIS MAY CAUSE SOME LOCATIONS TO
EXPERIENCE TRAINING OF HEAVY RAINFALL RATES...MAXING OUT IN THE
1-2 IN/HR RANGE. 

OTTO

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

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

LAT...LON   39011378 38961271 38741166 38501141 37481037 
            36481022 35601074 35131217 35741329 35761503 
            36421563 37231597 38331571 38751478