Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Fri Aug 11 2023 20:51:12

AWUS01 KWNH 112050
FFGMPD
NMZ000-AZZ000-UTZ000-120249-

Mesoscale Precipitation Discussion 0905
NWS Weather Prediction Center College Park MD
450 PM EDT Fri Aug 11 2023

Areas affected...southern/central Utah, eastern Arizona, western
New Mexico

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

Valid 112049Z - 120249Z

Summary...Slow moving, diurnally driven thunderstorm activity
could pose a risk of localized flash flooding in sensitive spots
this afternoon/early evening.

Discussion...Persistent insolation and weak to moderate
instability was allowing for deep convection to materialize over
southern Utah and portions of north-eastern through southern
Arizona and western New Mexico.  The storms have tended to form
along ridgelines and slowly propagate, with weak/negligible flow
aloft supporting 0-5 knot storm motions at times.  The storms are
also in an environment characterized by 0.8-1.4 inch PW values -
higher in southern Arizona - that were likely supporting heavy
rainfall at times beneath the deeper convection.  Spots of 1+
inch/hr rain rates were apparent per MRMS as well - also
suggesting localized flash flood potential.  As typical for the
region and time of year, the greatest flash flood potential is
likely tied to where spotty heavier rain rates can materialize
across sensitive terrain (i.e., low spots/slot canyons), where a
quick inch of rainfall could cause extreme, localized runoff.

The ongoing trends are expected continue in spots through the peak
of the diurnal cycle, with minimal larger-scale organization
suggestive of an eventual weakening trend 1) after dark and/or 2)
where convective overturning has resulted in broader low-level
stabilization.  Models/CAMs suggest that this downturn in
convective trends will begin in earnest between 02-04Z tonight.

Cook

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!4gtOFrkXYe00uX1DCpjLJ2aoKHX2P6hTStrnjIQuG05caaQYYJqQJiYhrAAIuKxYIZEz=
uJ2zTQdjrDdoVvt4D1A_xpU$  for graphic product...

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

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

LAT...LON   39041157 38711048 38020970 36780920 36020860=20
            35250755 34140637 33820572 33150620 31760791=20
            31340830 31291106 31681213 32661211 34551157=20
            35691211 37331336 38651361=20

=3D =3D =3D
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