438
AWUS01 KWNH 250101
FFGMPD
AZZ000-UTZ000-NVZ000-250600-

Mesoscale Precipitation Discussion 0997
NWS Weather Prediction Center College Park MD
900 PM EDT Sun Aug 24 2025

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

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

Valid 250100Z - 250600Z

SUMMARY...Additional scattered areas of flash flooding will remain
possible going through the evening hours from clusters of
monsoonal showers and thunderstorms.

DISCUSSION...The late-day GOES-W IR satellite imagery in
conjunction with radar continues to show broken clusters of
monsoonal showers and thunderstorms impacting portions of central
and northern AZ and southern UT. The activity continues to be
embedded within a moist and unstable airmass being facilitated by
the synoptic scale monsoon pattern across the Southwest.

There are still some pockets of untapped instability locally over
northwest AZ and southern UT with some MLCAPE values of 1000+ J/kg
noted. However, the region is gradually being convectively
overturned, and this should support a gradual downward trend in
the coverage and intensity of convection by later this evening.
This is also being advertised by recent runs of the experimental
WoFS and the broader hires model consensus.

Regardless, the ongoing clusters of convection will still be
capable of producing heavy rainfall rates of up to 1.5 inches/hour
over the next few hours, with some additional spotty amounts of up
to 2 inches going through late this evening.

Some additional scattered areas of flash flooding will be
possible, and this will include localized impacts potentially to
the slot canyon areas of southern UT and some of the sensitive
burn scar areas over central and especially northern AZ. Some of
the normally dry washes may also be affected by suddenly rising
flood waters.

Orrison

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

ATTN...WFO...FGZ...GJT...PSR...SLC...VEF...

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

LAT...LON   38371264 38371099 37450984 36150943 34330968
            33321093 33291241 33791347 34691396 35861411
            36771404 37991351