MESOSCALE PRECIPITATION DISCUSSION 0493
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
503 PM EDT FRI JUL 20 2018

AREAS AFFECTED...SOUTHERN UT...AZ...WESTERN NM

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

VALID 202100Z - 210300Z

SUMMARY...SHOWERS AND THUNDERSTORMS WILL GRADUALLY DEVELOP AND
EXPAND IN COVERAGE OVER THE NEXT FEW HOURS. SOME FLASH FLOODING
WILL BE POSSIBLE.

DISCUSSION...SCATTERED AREAS OF SHOWERS AND THUNDERSTORMS ARE
DEVELOPING OVER THE MORE OROGRAPHICALLY FAVORED AREAS OF NORTHWEST
TO SOUTHEAST AZ AND ALSO WESTERN NM AS STRONG DIURNAL HEATING
CONTINUES AND RESULTS IN SUFFICIENT INSTABILITY FOR CONVECTIVE
DEVELOPMENT. IN FACT...THE LATEST RAP ANALYSIS DEPICTS AS MUCH AS
2000 TO 3000 J/KG OF MLCAPE OVER SOUTH-CENTRAL AZ.
MEANWHILE...MOISTURE PROFILES IN CONCERT WITH THE MONSOON PATTERN
ARE AGAIN RATHER ANOMALOUS WITH PWATS OVER PORTIONS OF SOUTHERN AZ
EXCEEDING 1.75 INCHES WHICH IS A SOLID 2 TO 3 STANDARD DEVIATIONS
ABOVE NORMAL.

GIVEN THE MOISTURE PROFILES...THE CONVECTION WILL AGAIN BE QUITE
EFFICIENT IN DRIVING HEAVY RAINFALL WITH RATES THAT COULD APPROACH
2 INCHES/HR. THE ACTIVITY WILL LIKELY REMAIN OROGRAPHICALLY
FOCUSED GOING THROUGH THE REMAINDER OF THE AFTERNOON...WITH THE
CONVECTION PERHAPS MOST CONCENTRATED OVER THE MOGOLLON RIM. SOME
ADDITIONAL LOCALIZED AREAS OF HEAVY RAINFALL MAY ALSO OCCUR AGAIN
OVER SOUTHERN UT.

THE LATEST HIRES CAM CONSENSUS SUPPORTS RAINFALL AMOUNTS OF AS
MUCH AS 2 TO 3 INCHES GOING THROUGH ABOUT 03Z. CONSIDERING THAT A
SIZABLE PORTION OF THIS COULD FALL IN AS LITTLE AS 1 TO 2
HOURS...FLASH FLOODING WILL BE POSSIBLE. THE AREAS MOST
SUSCEPTIBLE AGAIN WILL TEND TO BE SLOT-CANYONS...WASHES AND ANY
AREAS INVOLVING BURN SCARS WHERE RUNOFF WILL BE GREATLY ENHANCED.

ORRISON

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

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

LAT...LON   39051162 38841090 37681107 36221123 35201084
            35140996 36160934 36480886 36170801 35190752
            34170745 32980787 32530899 31610983 31321056
            31401139 31691193 32251223 33041209 33921231
            34301271 34841383 35811409 36801376 37801316
            38701238