MESOSCALE PRECIPITATION DISCUSSION 0428
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
452 PM EDT FRI AUG 07 2015
 
AREAS AFFECTED...SOUTHERN UT/NORTHERN AND EASTERN AZ... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 072051Z - 080106Z
 
SUMMARY...CONVECTION CONTINUES TO REMAIN WELL ORGANIZED ACROSS
NORTHERN AZ GIVEN THE STRONGER MID/UPPER LEVEL DYNAMICAL SUPPORT.
TO THE SOUTH...SLOW CELL MOTIONS ALONG THE HIGHER TERRAIN HAVE
ALREADY LED TO LOCALIZED HEAVY RAINFALL. EXPECT BOTH REGIONS TO BE
ACTIVE INTO THE EVENING HOURS WITH FLASH FLOODING POSSIBLE.

DISCUSSION...A MID/UPPER CLOSED LOW CURRENTLY SPINNING IN THE
VICINITY OF RENO NV IS SLOWLY MOVING TOWARD THE NORTH AND EAST.
BROAD UPPER DIFFLUENCE IS EVIDENT IN THE 300-MB WIND VECTORS WITH
A PRONOUNCED JET STREAK IN EXCESS OF 80 TO 90 KNOTS OVERSPREADING
THE REGION. REGARDING MOISTURE ACCESS...A MULTI-DAY LOOP OF THE
EXPERIMENTAL LAYERED PRECIPITABLE WATER PRODUCT SHOWS A PAIR OF
MOISTURE CHANNELS BETWEEN 500-300 MB STREAMING THROUGH THE DESERT
SOUTHWEST...ONE OF WHICH IS EXTENDING AWAY FROM THE POST-TROPICAL
REMAINS OF GUILLERMO. SURFACE MOISTURE ACROSS NORTHERN AZ IS MUCH
BETTER TODAY AFTER A BOUT WITH HIGH DEW POINT DEPRESSIONS THE
PREVIOUS DAY. SUFFICIENT MOISTENING OF THE COLUMN HAS LED TO
HIGHER PRECIPITATION EFFICIENCY WITH LOCALLY HEAVY RAINFALL
CONTINUING TO AFFECT THE NORTHERN EXTENT OF AZ. CELL MOTIONS HAVE
GENERALLY BEEN TOWARD THE NORTHEAST ALTHOUGH REGENERATION
CONTINUES TO OCCUR TO THE SOUTH WHERE MODEST CAPE AND DIFFULENT
FLOW ALOFT OVERLAP.

LOOKING TO THE SOUTH...CONVECTION CONTINUES TO BREAK OUT ACROSS
EASTERN AZ WHERE HIGHER INSTABILITY EXISTS. THIS REGION HAD SEEN
BETTER SOLAR INSOLATION ALTHOUGH CIRRUS DEBRIS HAS CLOUDED UP
SECTIONS OF THE STATE IN THE PAST COUPLE OF HOURS.
REGARDLESS...SLOW CELL MOTIONS COMBINED WITH THE COMPLEX TERRAIN
SUGGESTS THE THREAT FOR FLASH FLOODING SHOULD REMAIN INTO THE
EARLY EVENING.

RECENT CAMS SUGGEST THE THREAT FOR HEAVY RAINFALL SHOULD GRADUALLY
WIND DOWN ACROSS EASTERN AZ AS THE HIGHER CAPE AIR IS EXHAUSTED.
HOWEVER...BETTER FORCING AND DYNAMICS TO THE NORTH SUGGEST THE
THREAT WILL CONTINUE TO MOVE TOWARD THE NORTH/EAST. LOCAL HEAVY
DOWNPOURS ACCOMPANIED BY CELL MERGERS WILL ENHANCE THE RISK FOR
FLASH FLOODING. 


RUBIN-OSTER

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

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

LAT...LON   38331275 38191046 36981000 35950935 35090910 
            33450927 32400966 32171073 32621140 33461141 
            34591100 35251119 35591188 35401350 36021407 
            37491385