MESOSCALE PRECIPITATION DISCUSSION 0543
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1247 PM EDT SUN JUL 23 2017

AREAS AFFECTED...PORTIONS OF AZ & SOUTHWEST NM

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

VALID 231646Z - 232246Z

SUMMARY...A PROGRESSIVE EASTERLY WAVE AT 700 HPA SHOULD LEAD TO
ENHANCED MONSOON CONDITIONS TODAY.  HOURLY RAIN RATES UP TO 2"
WITH LOCAL AMOUNTS TO 4" ARE EXPECTED.

DISCUSSION...EXPERIMENTAL GOES-16 0.86 MICRON/"VEGGIE BAND"
IMAGERY SHOWS CLOUDINESS ASSOCIATED WITH SATURDAY'S BATCH OF
THUNDERSTORM ACTIVITY BREAKING UP AND NEW CUMULIFORM CLOUDS ACROSS
SOUTHEAST AND CENTRAL AZ.  POSSIBLE MCVs LURK ACROSS SOUTHEAST AZ
AND NORTHWEST AZ.  PRECIPITABLE WATER VALUES ARE 1-2" PER RECENT
GPS DATA.  AN INVERTED TROUGH AT 700 HPA HAS OCCASIONALLY SHOWN UP
IN THE VAD WIND PROFILES WEST OF THE KEWX RADAR IN SOUTHEAST AZ. 
INFLOW AT 700 HPA IS 10-15 KTS AND CYCLONIC, ABOVE THE VALUE OF
THE MEAN 850-400 HPA WIND.  ML CAPE VALUES OF 500-1000 J/KG EXIST
ACROSS SOUTHERN AZ, WITH CIN ERODED ACROSS SOUTHEAST AZ BEHIND THE
INVERTED TROUGH PER SPC MESOANALYSES.

RAP FORECAST SUGGEST THAT THE EASTERLY WAVE AT 700 HPA MIGRATES
WESTWARD THROUGH AZ WITH TIME.  THE 06Z SSEO NEIGHBORHOOD
PROBABILITIES SUGGEST CONVECTIVE DEVELOPMENT SHOULD OCCUR
PRIMARILY AFTER 18Z, THOUGH RECENT VISIBLE IMAGERY IMPLIES THE
PROCESS APPEARS TO BE UNDERWAY.  THE PROBABILITIES SHOW >50%
EXCEEDANCE OF AREA FLASH FLOOD GUIDANCE VALUES ACROSS SOUTHEAST AZ
AFTER 21Z.  WITH ML CAPES EXPECTED TO BUILD ANOTHER 1000-1500
J/KG, WOULD EXPECT CONVECTION TO BUILD WITH INCREASING VIGOR WITH
TIME AND MOVE WESTWARD.  HOURLY RAIN RATES UP TO 2" WITH LOCAL
AMOUNTS UP TO 4" ARE POSSIBLE, PARTICULARLY OVER THE TOPOGRAPHY OF
SOUTHEAST AND NORTH-CENTRAL AZ.  THIS DEGREE OF RAINFALL WOULD BE
PROBLEMATIC IN URBAN AREAS, NEAR BURN SCARS, AND WITHIN AREA
WASHES/ ARROYOS/ GULCHES.

ROTH

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

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

LAT...LON   36991374 36991216 36681199 35441141 34621022
            34290891 34460801 34090749 33720748 33180767
            32660790 31910812 31300816 31300815 31280931
            31341168 33271193 34391339 34801429 35531470
            35921433 36441385 36521426 36621425