Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Sep 06 2025 09:32:27

AWUS01 KWNH 060932
FFGMPD
AZZ000-NVZ000-CAZ000-061330-

Mesoscale Precipitation Discussion 1053
NWS Weather Prediction Center College Park MD
531 AM EDT Sat Sep 06 2025

Areas affected...southeastern Nevada, western Arizona, far
southeastern California

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

Valid 060930Z - 061330Z

Summary...A long-lived thunderstorm complex should persist for a
few more hours and possibly prompt instances of flash flooding.

Discussion...A long-lived MCS currently extends from near Las
Vegas east to near the Grand Canyon.  The complex remains
organized and well positioned within a moist/unstable axis along
the Colorado River Valley (1+ inch PW, 1000 J/kg SBCAPE). Weak
southerly low-level flow was enhancing convergence along the
leading edge of the complex, while mid-level vort maxima were
likely aiding in ascent to help maintain the intensity of the
complex.  Areas of 1-2 inch/hr rain rates continue to be estimated
per MRMS beneath the strongest, most persistent activity, which
has likely led to excessive runoff in a few locales (based on MRMS
Flash responses).

Current trends suggest that the complex will continue to drift
southward along the Colorado River into western Arizona along the
aforementioned moist/unstable axis.  Boundary layer cooling has
been slow to take hold in this area, and point forecast soundings
suggest continued potential for sustained updrafts.  Weak
southerly flow at 850mb should also help maintain the MCS for a
few more hours.  Gradually weaker mid-level lapse rates exist with
southern extent though, suggesting that the complex may weaken
eventually.  The specific timing of the onset of this weakening
trend is uncertain.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!6Vxrhu5q0nQa3eQBDPUhUuJEMCj6hdoA8MKvEEVZtWX_9D_CP_NdVO5kcXjks7DjaZlX=
wJWou7iVP2uuMVjlFUegws8$  for graphic product...

ATTN...WFO...FGZ...PSR...VEF...

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

LAT...LON   36901451 36401339 35161254 33761289 33711463=20
            35891527=20

=3D =3D =3D
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