729
AWUS01 KWNH 170723
FFGMPD
AZZ000-CAZ000-171220-
MESOSCALE PRECIPITATION DISCUSSION 0750
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
322 AM EDT FRI JUL 17 2026
AREAS AFFECTED...PORTIONS OF ARIZONA
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 170720Z - 171220Z
SUMMARY...ISOLATED FLASH FLOOD POTENTIAL CONTINUES PRIMARILY
ACROSS CENTRAL ARIZONA.
DISCUSSION...SCATTERED TO NUMEROUS CONVECTIVE CELLS INITIALLY
CONCENTRATED ACROSS THE EASTERN HALF OF ARIZONA HAVE CONGEALED
INTO A SLOW-MOVING, FORWARD PROPAGATING COMPLEX ACROSS CENTRAL
PORTIONS OF THE STATE. THE LEADING EDGE OF THIS COMPLEX IS
LOCATED ALONG A LINE EXTENDING FROM NEAR BUCKEYE THROUGH PHOENIX
TO NEAR TUCSON. WEAK SOUTHERLY LOW-LEVEL FLOW (AROUND 5-10 KNOTS
AT 850MB) ORIENTED PERPENDICULAR TO THE LEADING EDGE OF THIS
COMPLEX IS PROVIDING ENOUGH ASCENT FOR MAINTENANCE OF UPDRAFTS
JUST NORTH OF THE AFOREMENTIONED BOUNDARY/LEADING EDGE. UPDRAFTS
WERE BEING MAINTAINED AMID ELEVATED INSTABILITY (ESTIMATED TO BE
AROUND 500 J/KG MLCAPE) AND VERY HIGH PW VALUES (APPROACHING 2
INCHES), SUPPORTING LOCALLY HEAVY RAINFALL. MRMS ESTIMATES OF 1
INCH/HR PERSIST NORTH OF PHOENIX, WHICH MAKES SENSE GIVEN THE
ENVIRONMENT.
WEAK STEERING FLOW WILL ALLOW FOR A SLOW WESTWARD PROPAGATION OF
THIS COMPLEX INTO PORTIONS OF WESTERN ARIZONA OVER THE NEXT 3-5
HOURS (THROUGH 12Z). A SLIGHT WEAKENING TREND TO THIS ACTIVITY
MAY ALSO BE OBSERVED, AS IS HINTED AT BY CAMS/HREF. LOCAL 1
INCH/HR RAIN RATES WILL LEAD TO SPOTS OF FFG EXCEEDANCE, WITH
EXCESSIVE RUNOFF/FLASH FLOOD CONCERNS EXISTING ESPECIALLY IN
TERRAIN-FAVORED LOW-LYING AREAS.
COOK
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...FGZ...PSR...TWC...VEF...
ATTN...RFC...STR...NWC...
LAT...LON 36131352 35521240 34601155 33651046 32791009
31861109 32461365 33001441 33901431 34621439
35781462
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