877
AWUS01 KWNH 122053
FFGMPD
AZZ000-UTZ000-NVZ000-CAZ000-130245-
MESOSCALE PRECIPITATION DISCUSSION 1027
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
452 PM EDT WED AUG 12 2026
AREAS AFFECTED...NORTHERN AZ...WESTERN NM...CENTRAL & SOUTHERN
UT...SOUTHERN NV...ADJ. CALIFORNIA...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 122100Z - 130245Z
SUMMARY...BROAD AREA OF LARGE SCALE ASCENT TO LOCALLY ENHANCED
MONSOON CONVECTIVE ACTIVITY TODAY. LOCALIZED RATES OF 1-1.25"
WITH POTENTIAL OF SOME CELL MERGERS/REPEATING FROM SW TO NE FOR
LOCALIZED 2"+ TOTALS. FLASH FLOODING REMAINS POSSIBLE.
DISCUSSION...GOES-E WV SUITE SHOWS LARGE SCALE CLOSED LOW AND
ASSOCIATED LONG WAVE TROUGH APPROACHING CENTRAL CALIFORNIA, WHICH
HAS RESULTED IN A DOWNSTREAM CHANGE IN OVERALL PATTERN AND FLOW
REGIME. COMPACT SHORTAVE THAT WAS OVER THE SOUTHWEST DESERTS OF
ARIZONA YESTERDAY WAS REINFORCED/ENHANCED BY LATENT HEAT RELEASE
FROM ACTIVITY OVERNIGHT INTO THIS MORNING, BUT THE SHIFT IN
PATTERN HAS STARTED TO LIFT IT NORTH-NORTHEAST,
ELONGATING/SHEARING IT ACROSS NW AZ. THE OLDER OUTFLOW CHANNEL
ALOFT REMAINS WELL DEFINED WITH ANTICYCLONIC CURVATURE INDICATIVE
OF RIGHT ENTANCE BROAD SCALE ASCENT PATTERN ACROSS UT INTO WY. AS
SUCH, DPVA FROM THE SHORTWAVE AND DIVERGENCE ALOFT DOWNSTREAM HAS
RESULTED IN BROAD ASCENT WITH INCREASE OF CONVECTIVE ACTIVITY
THROUGHOUT THE EARLY AFTERNOON AND THIS TREND CONTINUES BASED ON
VISIBLE/10.3UM EIR LOOP ACROSS THE AREA.
AS THE WAVE EXITS, LOW LEVEL FLOW IS INCREASING ACROSS THE LOWER
COLORADO RIVER VALLEY PROVIDING INCREASED MOISTURE FLUX UP AND
THROUGH THE MCV INTO S UT. PWATS OF 1.5-1.75" AREA STARTING TO BE
OBSERVED THROUGH THE LOWER VALLEYS EVEN AS FAR AS INTO SW UT
THOUGH, HIGHER VALUES ARE STARTING TO INCRASE TO OVER 1.25"
THROUGH THE LOWER SLOPES OF UTAH'S CENTRAL MOUNTAINS. FURTHER
INSOLATION INTO THE HIGHER THETA-E AIR MOVING IN, WILL STEADILY
INCREASE INSTABILITY FROM 1500-2000+ J/KG TO SUPPORT STRONGER
UPDRAFTS. AS SUCH, CELLS WILL BE CAPABLE OF 1-1.5"/HR DEPENDING
ON ELEVATION AND LOCALIZED ISALLOBARIC INFLOW. ADDITIONALLY, DEEP
LAYER FLOW IS SSW TO NNE AND MAY PROMOTE A FEW REPEATING CELLS
WITH TIME; THOUGH SOUTH OF THE SHORTWAVE, STRONGER UPSLOPE FLOW
MAY BE EQUAL TO DEEPER LAYER STEERING RESULTING IN EITHER
STATIONARY MOTION OR EVEN SLOW SOUTHWARD BACK-BUILDING INTO SW AZ.
IN THOSE CASES, LOCALIZED ENHANCED TOTALS OF 2-2.5" ARE POSSIBLE
GIVEN LONGER RESIDENCY, BUT MOST STORMS WILL RESULT IN FOCUSED
1-2" TOTALS. AS NORMAL WITH MONSOON CONVECTION, WHERE THE RAIN
FALLS RELATIVE TO TERRAIN/STEEP SLOPES AND OR ROCKY/BARREN GROUNDS
WILL ENHANCE RISK OF LOCALIZED FLASH FLOODING.
GALLINA
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...FGZ...GJT...PSR...SLC...VEF...
ATTN...RFC...RSA...STR...NWC...
LAT...LON 40471083 40080977 38270936 36420979 34641087
33441261 33301454 34491629 36331576 37771476
40071237
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