MESOSCALE PRECIPITATION DISCUSSION 0429
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
906 PM EDT FRI AUG 07 2015
 
AREAS AFFECTED...EXTREME SOUTHERN UT...NORTHERN TO
CENTRAL/SOUTHERN AZ... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 080106Z - 080506Z
 
SUMMARY...DEEP CONVECTION CONTINUES TO THRIVE IN A MOIST AND
STRONGLY UNSTABLE ENVIRONMENT. CLOUD TOPS HAVE WARMED IN RECENT
SCANS BUT WARM RAIN PROCESSES HAVE SUPPORTED HEFTY PRECIPITATION
RATES. THE ACTIVITY SHOULD CONTINUE TO BUILD TOWARD THE WEST WHERE
SKIES ARE A BIT MORE CLOUD-FREE.

DISCUSSION...AHEAD OF A COMPACT MID/UPPER LOW ACROSS NORTHWESTERN
NV...A STRONGLY DIFFLUENT UPPER PATTERN HAS SUPPORTED DEEP
CONVECTION ACROSS MUCH OF AZ. RECENT GPS DATA AND 00Z RAOB
INDICATE A VERY MOIST ATMOSPHERE IN PLACE WITH PWATS APPROACHING
1.90 INCHES NEAR PHOENIX AZ. SUCH VALUES ARE NEAR THE MAX MOVING
AVERAGE PER THE SPC SOUNDING CLIMATOLOGY PAGE. SOME
LOCATIONS...PARTICULARLY IN CENTRAL AZ...STILL HAVE A 20 TO 30
DEGREE DEW POINT DEPRESSION SPREAD WHICH HAS RESULTED IN SOME
RAINFALL LOSS VIA EVAPORATIVE PROCESSES. HOWEVER...MOST AREAS HAVE
EFFECTIVELY SEEN THEIR PROFILES BECOME MOIST ADIABATIC WITH
FREEZING LEVELS EXCEEDING 13 KT. THESE WARM RAIN PROCESSES HAVE
SUPPORTED HOURLY RATES IN THE 1 TO 1.50 INCH RANGE VIA DUAL-POL
ESTIMATES. EXPECT SUCH RATES TO PERSIST A FEW MORE
HOURS...PARTICULARLY IN AREAS WHERE OROGRAPHICS HAVE COME INTO
PLAY.

HIGH-RESOLUTION GUIDANCE HAS TENDED TO FAVOR SHUTTING DOWN THE
ACTIVITY ON THE NORTHERN EDGE OF THE MPD AREA. THIS APPEARS
REASONABLE GIVEN THE AIR MASS BECOME MORE STABLE VIA CONVECTIVE
OVERTURNING THIS AFTERNOON/EVENING. HOWEVER...THERE DOES SEEM TO
BE A BETTER FOCUS FARTHER SOUTH IN REGIONS WHICH HAVE BEEN MORE
CLOUD-FREE TODAY. ADDITIONALLY...SOME OF THE ACTIVITY FROM EXTREME
NORTHWESTERN MX SHOULD BE ABLE TO CROSS THE INTERNATIONAL BORDER
CAUSING ADDITIONAL HEAVY RAINFALL FOR SOUTH-CENTRAL AZ.


RUBIN-OSTER

ATTN...WFO...FGZ...PSR...TWC...

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

LAT...LON   36411036 36240982 35890945 35290946 34741014 
            33761046 31921028 31251095 31661212 33221244 
            34281224 35031236 35581231 36011196 36401118