Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Sep 04 2023 04:42:28

AWUS01 KWNH 040442
FFGMPD
AZZ000-UTZ000-NVZ000-041015-

Mesoscale Precipitation Discussion 1033
NWS Weather Prediction Center College Park MD
1241 AM EDT Mon Sep 04 2023

Areas affected...southwestern into central UT

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

Valid 040439Z - 041015Z

Summary...Brief training and repeating of showers and
thunderstorms will pose an isolated flash flood threat across
portions of southwestern to central UT. Peak rainfall rates of 0.5
to 1.0 inches in an hour or less and localized totals of 1-2
inches will be possible.

Discussion...04Z GOES West water vapor imagery showed a mid-upper
level trough over central NV, tracking eastward along with
increasing upper level diffluence downstream over UT. Infrared and
regional radar imagery showed a broken axis of showers and
thunderstorms, extending from west-central UT into far
southeastern NV, located at the leading edge of the upper trough.
04Z SPC mesoanalysis data indicated a small pocket of weak
instability in this area with 250-750 J/kg MLCAPE. While there was
some relatively dry air aloft above 500 mb as seen in CIRA LPW
imagery, the low to mid-levels remained moist with total
precipitable water values representing standardized anomalies of
+1 to +2 over most of UT.

850-300 mb winds, a proxy for cell motions, were southwesterly at
a progressive 40 kt, but a zone of enhanced southwesterly 700 mb
winds between 20-30 kt were also present ahead of the trough. Some
minor increase in the 700 mb flow is forecast by the RAP with
speeds approaching 40 kt on a localized basis. Some expansion of
showers and thunderstorms is expected over southwestern UT over
the next 1-2 hours, with movement off toward the northeast. The
remaining weak instability and unidirectional southwesterly flow
may support some repeating and brief cell training with rainfall
rates of 0.5 to 1.0 inches per hour or less than an hour along
with localized totals of 1-2 inches over the next 6 hours. This
could result in isolated flash flooding into the sensitive terrain
of the Wasatch and Pavant Ranges into southern portions of the
state with potential overlap of area national parks and recent
burn scars.

Otto

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!4mlIWLIog3eKViL7FsqGZcLQgeW9h4-SnbIhlCIr4IPcaFOb4k16brD9nBtZWGdTDAbi=
d0iIw1tocafZ3N7687ITu0A$  for graphic product...

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

ATTN...RFC...CBRFC...NWC...

LAT...LON   40931131 40431103 39351125 38751151 37851176=20
            37121243 36871371 37761416 39171343 40811207=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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