Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Jul 18 2025 18:04:28

AWUS01 KWNH 181804
FFGMPD
AZZ000-UTZ000-NVZ000-CAZ000-190002-

Mesoscale Precipitation Discussion 0745
NWS Weather Prediction Center College Park MD
204 PM EDT Fri Jul 18 2025

Areas affected...portions of eastern California and
southern/eastern Nevada

Concerning...Heavy rainfall...Flash flooding likely

Valid 181802Z - 190002Z

Summary...Heavy downpours are concentrated around a mid-level low
center near the California/Nevada border region just west of Las
Vegas.  Rain rates with these downpours are sufficient for a flash
flood threat, and convection/flash flood potential should expand
in coverage through the afternoon hours.

Discussion...Deep convection has concentrated near a remnant MCV
centered about 50 E NID.  Abundant insolation near the MCV has
resulted in an expansion of convective coverage in this vicinity
and near adjacent ridgelines across the southern Sierra,
east-central Nevada, southwestern Utah, and northwestern Arizona.
The storms nearest the MCV are located in an axis of moisture and
instability (1.3 inch PW values and 1000 J/kg MLCAPE), which has
prompted areas of rain rates exceeding 1 inch/hr.  Flash flooding
is likely across sensitive terrain/low-lying areas nearest the MCV
in the short term.

Over time, both models and observations depict an expansion of
convective coverage across much of the discussion area in tandem
with peak heating hours.  The heaviest rain rates should be
concentrated in southern Nevada and eastern California, although
weak wind fields aloft and PW values exceeding 0.7 inch should
support areas of at least 0.5 inch/hr rain rates farther away from
the aforementioned moist axis.  These rates should pose a flash
flood risk - especially in terrain-favored areas/dry washes and
slot canyons.  This primarily diurnally driven risk should persist
beyond 00Z this afternoon given the abundance of sunshine and
relatively slow movement of meso-to-synoptic scale features
supporting convection.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!65gM5XiCz7evUlWBLDVXWAvUPNe1XnJmlxtzkS0vL_Wn8GfMolTlO_NVUABruf1_3t1V=
AT4r6dMSg3IOUjbnhGir3vw$  for graphic product...

ATTN...WFO...FGZ...HNX...LKN...PSR...REV...SGX...SLC...VEF...

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

LAT...LON   40071412 39911224 38831101 37781124 36771151=20
            35791222 34711175 34121169 34261241 34711378=20
            35111489 34411555 33801679 34641743 35491836=20
            36661875 38031788 39621604=20

=3D =3D =3D
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