MESOSCALE PRECIPITATION DISCUSSION 0593
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
240 PM EDT SAT JUL 29 2017

AREAS AFFECTED...AZ...WESTERN NM

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

VALID 291845Z - 300045Z

SUMMARY...SCATTERED CONVECTION...INITIALLY TIED TO THE
TERRAIN...IS EXPECTED TO PRODUCE HOURLY RAINFALL RATES BETWEEN
1.00 AND 1.50 INCHES...WHICH COULD RESULT IN A FLASH FLOOD THREAT
THROUGH THE AFTERNOON.

DISCUSSION...THE EXPERIMENTAL GOES-16 CLEAN IR IMAGES SHOWED AN
EXPANSION OF CELLS WITH RAPIDLY COOLING TOPS...PARTICULARLY OVER
THE TERRAIN OF WESTERN NM...WHERE A LOW  LEVEL EAST SOUTHEAST FLOW
IS FOCUSING MOISTURE AND INSTABILITY IN AN UPSLOPE FLOW. THE
CONVECTION IS FORMING IN AN AXIS OF 500-1000 J/KG OF MLCAPE
STRADDLING THE AZ/NM BORDER...WHERE THE CIN HAS BEEN ERODED. 

THE BEST MOISTURE ASSOCIATED WITH THE MONSOONAL FLOW IS FOCUSED
OVER SOUTHWEST AZ...WHERE PRECIPITABLE WATER VALUES ARE CLOSER TO
2.00 INCHES. HOWEVER...THE UPSLOPE FLOW IS TRANSPORTING 1.00/1.25
INCH PRECIPITABLE WATER ONTO THE WESTERN NM TERRAIN. THE
CONVECTION HAS SHOWN LITTLE MOVEMENT ON THE KHDX RADAR...AS IT IS
INITIALLY TIED TO THE TERRAIN.

THE 850-300 MB FLOW IS FAIRLY WEAK OVER EASTERN AZ/WESTERN
NM...WHICH SUGGESTS THAT CONVECTION THAT DEVELOPS MOVES SLOWLY...
INCREASING THE POTENTIAL FOR CELL MERGERS AND SHORT TERM TRAINING.
THE MOST RECENT HRRR INDICATED THE POTENTIAL FOR LOCAL 1.00/1.50
INCH HOURLY RAINFALL RATES...AND BASED ON THE MOISTURE PROFILES
AND THE SLOW CELL MOTIONS...THESE AMOUNTS SEEM PLAUSIBLE. THE MOST
RECENT HRRR PERCENT OF SOIL MOISTURE PRODUCT SHOWED AREAS WITH
NEARLY SATURATED SOILS OVER PORTIONS OF EASTERN AZ...MAKING THEM
MORE SUSCEPTIBLE FOR FLASH FLOODING.

FURTHER SOUTHWEST ACROSS SOUTH CENTRAL AZ...AN OLD MCV COULD
PROVIDE A FOCUS FOR THE DEEP MOISTURE AND MARGINAL INSTABILITY
(WHICH IS BATTING CIN AT THAT MOMENT) FOR ADDITIONAL CONVECTIVE
DEVELOPMENT. IN THIS AREA...THERE IS SLIGHTLY MORE PRONOUNCED MID
LEVEL FLOW THAN FURTHER EAST...WHICH COULD MITIGATE AN ENHANCED
FLASH FOOD THREAT TO SOME DEGREE.

THE THREAT COULD PERSIST PAST 00Z...AND THE THREAT WILL BE
REEVALUATED AT THAT TIME.

HAYES

ATTN...WFO...ABQ...EPZ...FGZ...PSR...TWC...

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

LAT...LON   36540730 36200635 35770646 34130728 33390741
            31660757 31230835 31221032 31591205 32201252
            34051182 34541193 35411223 35651213 35731183
            35611156 34931106 34381067 34180992 35060942
            36110924