Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Aug 03 2024 18:41:32

AWUS01 KWNH 031841
FFGMPD
NMZ000-AZZ000-UTZ000-040040-

Mesoscale Precipitation Discussion 0793
NWS Weather Prediction Center College Park MD
240 PM EDT Sat Aug 03 2024

Areas affected...Much of AZ into Central and Southern UT

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

Valid 031840Z - 040040Z

SUMMARY...Scattered areas of monsoonal shower and thunderstorm
activity can be expected today across much of AZ and up across
central and southern UT today. Isolated to widely scattered
instances of flash flooding will be likely given concerns of
intense rainfall rates and slow cell-motions. The area burn scar
locations, dry washes and slot canyons will be most susceptible to
impacts.

DISCUSSION...The latest GOES-E Day Cloud Phase RGB satellite
imagery shows CI underway across some of the high terrain of the
Mogollon Rim in AZ and also some of the higher terrain of southern
UT. Strong diurnal heating has led to SBCAPE values reaching
locally 1000 to 2000+ J/kg already, and a further destabilization
of the boundary layer is expected over the next several hours as
strong surface-based heating continues. The airmass is quite
moist, with PWs locally 1 to 2 standard deviations above normal.
The greater PW anomalies are noted up across central and southern
UT where the latest CIRA-ALPW data shows a fair amount of moisture
extending up through the 500/300 mb layer.

Over the next several hours, there will be a further expansion of
at least scattered areas of showers and thunderstorms given the
increasing instability and evolution of differential heating
boundaries and orographic forcing. And while the storms will be
most prevalent over the higher terrain, the convection will expand
out away from the terrain in time into some of the open desert
locations.

The presence of relatively anomalous moisture across these areas
and already rather elevated instability parameters suggests
rainfall rates will be locally quite intense, and capable of
approaching 2"/hour. Cell-motions will be rather slow too, and
with some localized concerns for the convection to be anchored
close to some of the higher terrain, there may be some storm
totals amounts by later this afternoon that reach 2 to 4 inches.

Isolated to widely scattered instances of flash flooding are
likely to materialize given the high rainfall rates, and the area
burn scar locations, dry washes and slot canyons will be most
susceptible to impacts.

Orrison

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!5DPU0bWmxqZEIrAp91kvYUlisJiQ9k_XYFGiCzIPqrPCIHwYJHWH_lXxLveqRk2oRbQw=
YqIiJxnb3tsTfTqnIIx9rsw$  for graphic product...

ATTN...WFO...ABQ...EPZ...FGZ...GJT...PSR...SLC...TWC...VEF...

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

LAT...LON   38981256 38951138 37841055 36991019 36080971=20
            34980914 34120888 33200883 31870943 31491014=20
            31731189 33201263 34611343 36171385 38081347=20
=20=20=20=20=20=20=20=20=20=20=20=20

=3D =3D =3D
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