Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Mon Jul 31 2023 18:33:43

AWUS01 KWNH 311833
FFGMPD
AZZ000-UTZ000-NVZ000-010030-

Mesoscale Precipitation Discussion 0820
NWS Weather Prediction Center College Park MD
232 PM EDT Mon Jul 31 2023

Areas affected...Southern UT...Southern NV...Northern AZ

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

Valid 311830Z - 010030Z

SUMMARY...Thunderstorms blossoming over parts of the region this
afternoon could contain excessive rainfall rates >1"/hr and may
lead to areas of flash flooding.

DISCUSSION...A shortwave trough in the Lower Colorado River Valley
is revolving around the southwest periphery of the upper level
ridge axis positioned over the southern High Plains. The
atmosphere has steadily destabilized as evident by the RTMA 3-hr
MLCAPE rising as much as 200-600 J/kg. PWs are highest in southern
NV and northern AZ where values look to hover around 1.25". PWs by
level will be lower in southern UT, but the 1" PWs there are near
the 90th climatological percentile. MLCAPE values will continue to
rise to values >1,000 J/kg in western AZ and southern NV, while
they range between 500-1,000 J/kg in southern UT.

Mid-level RH values in the region will rise above 80%, but low
level RH values remain quite dry. This should help to cap the
potential on warm rain processes within developing thunderstorms
and limit the area extent of possible instances of flash flooding.
That said, mean cloud layer winds will be <10 knots and both the
available moisture and instability would support >1"/hr rainfall
rates. The 12Z HREF shows 30-40% probabilities for >1"/hr rainfall
amounts this afternoon with the potential for >1.5"/hr rates
within the most intense cells. Pockets of the highlighted region
have picked up >300% of normal rainfall over the past 7 days,
making these areas most susceptible to possible flash flooding.
Any residual burn scars and dry washes are also prone to flash
flooding this afternoon.

Mullinax

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!5FpoCvMHtEtqXOVGp-rL7o4RlJclzQpg_P2kM3znQJvL0oIipCuOLHqwftnFYQqTenjx=
Je1LnHsz2cdHazqbQGQHX8Y$  for graphic product...

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

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

LAT...LON   39001212 38701066 37711072 36661106 34551175=20
            34331295 34881419 35971470 37401470 38471386=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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