Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Sep 05 2025 21:52:48

AWUS01 KWNH 052152
FFGMPD
UTZ000-NVZ000-CAZ000-060345-

Mesoscale Precipitation Discussion 1050
NWS Weather Prediction Center College Park MD
551 PM EDT Fri Sep 05 2025

Areas affected...Great Basin & Southwest UT

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

Valid 052150Z - 060345Z

SUMMARY...Numerous thunderstorms capable of producing rainfall
rates around 1"/hr in some cases may lead to additional areas of
flash flooding.

DISCUSSION...A negatively titled 250mb trough over central
California is providing modest upper-level ascent over the
southern Sierra Nevada and Great Basin this afternoon. GOES-19
satellite imagery shows cooling cloud tops aloft as storms tap
into as much as 500 J/kg of MLCAPE per RAP mesoanalysis. In
addition, PWATs are unusually high across the region, topping
0.75" for most areas and thus placing these PWAT values above the
90th climatological percentile. PWATs are closer to 1" in southern
NV and southwest UT. Given the initially strong surface based
heating and synoptic-scale support from the approaching 250mb
trough axis, look for storms to continue into this evening as
emanating outflow boundaries kick-start new storms within the
highlighted region. The available PWATs and MLCAPE should support
maximum hourly rainfall rates around 1"/hr in the most intense
storms. NASA SPoRT-LIS does show some parts of western Nevada and
the eastern slopes of the Sierra Nevada featuring >90th percentile
soil moisture values, so some soils may be rather sensitive to
these heavier rainfall rates. Additional flash flooding is
possible, especially in dry washes and areas with poor drainage.

Mullinax

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!5c7JB5z5XzZgrfBr-3Resna_Nd1fz-OY-bnCUpGC6iQjuQUM_OkWmeOqi3-KL2mXQ7ZO=
FZneN8XdNPBQSSwIn3hpZos$  for graphic product...

ATTN...WFO...LKN...REV...SLC...VEF...

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

LAT...LON   41241863 40851733 40321599 39231446 38931324=20
            38691228 38231182 37351191 37231318 37261432=20
            36851583 37051700 37151812 37891890 38531925=20
            39721955 40901951=20

=3D =3D =3D
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