Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Oct 12 2025 05:38:41

AWUS01 KWNH 120538
FFGMPD
AZZ000-UTZ000-NVZ000-121037-

Mesoscale Precipitation Discussion 1184
NWS Weather Prediction Center College Park MD
137 AM EDT Sun Oct 12 2025

Areas affected...northwestern Arizona, southern Utah

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

Valid 120537Z - 121037Z

Summary...Scattered thunderstorms are quickly developing across
the discussion area and producing 0.5-1.0 inch/hr rain rates.  A
few instances of flash flooding are possible.

Discussion...Robust thunderstorm activity is being forced by the
approach of a stout mid-level disturbance over Nevada currently.=20
The storms are embedded within a warm/moist axis along the
Colorado River, with 0.7-0.9 inch PW values and a narrow axis of
1000 J/kg SBCAPE along the Nevada/Arizona border area.=20
Convergence within this axis was also supporting ongoing updrafts.
 The storms were embedded in relatively fast deep layer flow
(approaching 50 knots per objective analyses), resulting in quick
storm motions. Localized backbuilding and training were the likely
mechanisms for enhancing local rain rates.

Unfortunately, these rates were falling in/near areas prone to
flooding, with slot canyons and local burn scars noted in the
area.  Ongoing trends are expected to continue for at least a few
hours.  Fast eastward storm motions may tend to carry some of the
convection eastward toward a slightly drier airmass with weaker
buoyancy, resulting in weakening.  Meanwhile, some backbuilding
may occur within the remaining warm/moist axis in northwestern
Arizona, contributing to a localized flash flood threat there.=20
Models suggest that this convective threat should be relatively
short-lived, ending by 09-10Z as cooler/drier air filters into the
discussion area from the northwest.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!_0SwQEhlfDReAPwWpzIzQjUrALF3GxWI77foRe-9F-okottKbSMgqIipQ7bHdyOkUkPX=
-mHgrcbUliWrMtohKG6aF_A$  for graphic product...

ATTN...WFO...FGZ...SLC...VEF...

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

LAT...LON   38091207 37391099 35451202 34491323 34561438=20
            35911468 37381378=20

=3D =3D =3D
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