Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Oct 10 2025 19:43:16

AWUS01 KWNH 101943
FFGMPD
AZZ000-UTZ000-NVZ000-CAZ000-110140-

Mesoscale Precipitation Discussion 1178
NWS Weather Prediction Center College Park MD
342 PM EDT Fri Oct 10 2025

Areas affected...southern CA, southern NV into central UT

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

Valid 101940Z - 110140Z

SUMMARY...Thunderstorms are expected to develop and expand in
coverage over portions of southern CA, southern NV into central UT
over the next 3-6 hours. Hourly rainfall of 0.5 to 1.5 inches is
expected along with isolated to widely scattered instances of
flash flooding.

DISCUSSION...GOES West visible imagery from 1930Z showed mostly
clear skies over the desert regions of southern CA into southern
NV and central UT, northwest of an extensive cloud shield to the
southeast. This region was located along the northwestern edge of
an anomalous moisture plume with standardized anomalies of PW
between 3 and 5 above the mean via the 12Z GFS. SPC mesoanalysis
data from 19Z showed 500-1000 J/kg MLCAPE across a majority of the
MPD threat area, but areas of low level inhibition remained,
especially across southern CA into NV.

Based on continued heating of the surface and advection of
moisture seen in OSPO ALPW imagery within the surface to 700 mb
layer, streaming north of Priscilla in the eastern Pacific,
further erosion of convective inhibition is expected through the
remainder of the afternoon. Convective development appears likely
within the next 1-2 hours, first over areas of higher terrain and
then spreading into the lower elevations with time. Some
augmentation of divergence aloft, within the right-entrance region
of a developing upper level jet max over southern NV will be
possible, aiding in the general forcing for ascent.

Unidirectional flow, generally from the southwest, will promote
areas of repeating and short term training within subtle low level
confluent axes. Coverage of cells may only become widely scattered
but the moisture-rich environment will promote efficient rainfall
production with 0.5 to 1.5 inches of rain in an hour expected.
These high rain rates are likely to result in at least isolated
areas of flash flooding, with a particular focus across any
population centers and burn scars, while otherwise impacting any
low lying and normally dry stream beds.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!8n0YZyRg_lRWv0PSZqz8psF9S-5A5bx8N5kI8ye1FG0rnFnmrsk281Y6QRNxwz1PmToJ=
1se-mmr7K4vc6iZuzvl_2ew$  for graphic product...

ATTN...WFO...GJT...LKN...PSR...SGX...SLC...VEF...

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

LAT...LON   39891291 39781057 39280943 38760947 38571076=20
            38211182 37571281 36281369 34951444 34281507=20
            33701587 33911680 34441741 35521712 36691669=20
            39011531=20

=3D =3D =3D
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