Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sun Aug 18 2024 21:48:06

AWUS01 KWNH 182148
FFGMPD
COZ000-WYZ000-AZZ000-UTZ000-190259-

Mesoscale Precipitation Discussion 0900
NWS Weather Prediction Center College Park MD
547 PM EDT Sun Aug 18 2024

Areas affected...Northwest Arizona...Utah...Southwest Wyoming

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

Valid 182146Z - 190259Z

Summary...Periodic training of showers and thunderstorms with
..75-1"/hr rainfall rates will continue this afternoon. Additional
flash flooding is likely, with considerable impacts possible atop
saturated soils and slot canyons.

Discussion...Showers and thunderstorms continue to stream
northeast across the Colorado River Basin on the periphery of a
monsoon high. Over the last 30 minutes, cloud top temperatures
with these cells have cooled rapidly over south-central Utah while
GLM flash density increased.

These intensifying storms firing along the periphery of a compact
shortwave, where DCVA can overlap areas sufficiently destabilized.
While instability over the region is a bit lower compared to
yesterday, RAP and objective analysis estimates show MUCAPE spots
of 1000-2000 J/kg with 1.1-1.2" PWATS (above the 90th percentile)
available to drive additional cells with intense rainfall rates
upwards 1"/hr. Vertical shear profiles are also a  weaker compared
to yesterday (25-30 kts) but still more than enough to support
organized bands of storms while also allowing for slightly slower
storm motions.

Through 3z, the 18z HREF 40km neighborhood probabilities maintain
a very high likelihood (60-70% chance) of rainfall amounts
exceeding 1" where cell coverage and training are maximized this
afternoon. This will likely lead to additional instances of
scattered flash flooding, with considerable impacts possible atop
areas saturated from previous rainfall and over vulnerable slot
canyon areas.

Asherman

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!9U66eLqrcVlxbJfGZwxOD0xni2T-RX1nu7S-vSNuK_m9zCbnCKsIIIRQnuovIbFfhAtO=
ufFVobk1uTBQcE0dir5Xi30$  for graphic product...

ATTN...WFO...FGZ...GJT...RIW...SLC...VEF...

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

LAT...LON   41561020 40230898 37461183 35621264 35631387=20
            37251401 39991312=20

=3D =3D =3D
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