541
AWUS01 KWNH 122032
FFGMPD
COZ000-NMZ000-AZZ000-UTZ000-130130-

Mesoscale Precipitation Discussion 1264
NWS Weather Prediction Center College Park MD
431 PM EDT Sat Sep 12 2026

Areas affected...Central and Southern UT...Northern AZ...Western
NM

Concerning...Heavy rainfall...Flash flooding possible

Valid 122031Z - 130130Z

SUMMARY...Scattered areas of monsoonal shower and thunderstorm
activity will continue into the evening hours. Isolated areas of
flash flooding will be possible for the more sensitive slot
canyon, burn scar and dry wash locations.

DISCUSSION...The latest GOES-W visible satellite imagery along
with LightningCast data and regional radar shows a gradual
increase in the coverage of scattered monsoonal shower and
thunderstorm activity.

The airmass over the region continues to destabilize with SBCAPE
values as high as 1000 to 2000 J/kg given strong solar insolation,
and this coupled with orographics should promote the additional
expansion of generally scattered areas of convection that will be
capable of producing high rainfall rates. This will be aided by
PWs running as high as 1 to 2 standard deviations above normal.

Hires model CAMs suggest some rainfall rates as high as 1 to 1.5
inches/hour, and some spotty 2+ inch rainfall potential where some
of these slow-moving areas of thunderstorm activity set up and
potentially even become nearly anchored to some of the higher
terrain.

Given the rather high rainfall rates and slow cell-motions in
general with the storms that do evolve going into the evening
hours, some isolated areas of flash flooding will be possible. The
normally dry washes, burn scar areas and slot canyon regions will
be at greatest risk as normal with this kind setup.

Orrison

...Please see www.wpc.ncep.noaa.gov for graphic product...

ATTN...WFO...ABQ...EPZ...FGZ...GJT...SLC...VEF...

ATTN...RFC...FWR...STR...NWC...

LAT...LON   39680942 39330886 38080886 36500891 35200775
            33750722 33220747 32960815 33140877 33850905
            34600959 34830987 35111025 35351090 35401148
            35331221 36091269 36771290 37451289 38181264
            38751232 39321167 39651061