Subj : MESO: Nws Weather Prediction Center College Park Md
To   : wx-storm@lists.illinois.edu
From : COD Weather Processor
Date : Sat Sep 27 2025 00:32:30

AWUS01 KWNH 270032
FFGMPD
NMZ000-AZZ000-270630-

Mesoscale Precipitation Discussion 1143
NWS Weather Prediction Center College Park MD
830 PM EDT Fri Sep 26 2025

Areas affected...Central to Southeast AZ

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

Valid 270030Z - 270630Z

SUMMARY...Clusters of heavy showers and thunderstorms will persist
into the evening hours across central to southeast AZ. Additional
areas of flash flooding will be likely with locally considerable
and life-threatening impacts still possible.

DISCUSSION...The latest GOES-W IR satellite imagery shows clusters
of cold-topped convection continuing to develop and locally
persist across areas of central to southeast AZ. Some of the
strongest convection and heaviest rainfall rates are currently
over portions of Pinal and Gila Counties. This is also where some
of the strongest low-level moisture convergence and pooling of
instability remains in place.

MLCAPE values of 1000 to 1500 J/kg are noted in general across
south-central AZ, and this coupled with larger scale
ascent/forcing associated with the slow approach of an upstream
closed low over eastern CA should continue to favor convection
with high rainfall rates at least for the next few hours.

Gradually there will be an increase in boundary layer CIN as the
evening progresses which will allow for the convective footprint
to begin to wane, but with elevated effective bulk shear of 30 to
40 kts across central to southeast AZ, there may be some
persistence of loosely organized convection through much of the
evening time frame.

Rainfall rates will still be capable of reaching 1 to 2
inches/hour based on the latest cloud top cooling trends over
Pinal and Gila Counties, and the experimental WoFS guidance
supports this for at least a couple more hours.

Some additional spotty totals may reach 2 to 3 inches where any of
the stronger cells continue to backbuild or train over the same
area. This will likely foster some additional areas of flash
flooding for the evening hours. Once again, there will be concerns
for enhanced dry wash/arroyo flash flooding along with potential
for localized burn scar impacts and urban flash flooding where
these heavier rains evolve. Thus, locally considerable and
life-threatening impacts will still be possible for at least a few
more hours.

Orrison

....Please see https://urldefense.com/v3/__http://www.wpc.ncep.noaa.gov__;!!=
DZ3fjg!4m7wuMKk98wpo0VQFaL3CKxKu7EsAOZQy19fm31h8dXEqp9ERppsD0smd1BP5N1ZoMJx=
wIiW4mM7n7aDKTloTVIR0_4$  for graphic product...

ATTN...WFO...EPZ...FGZ...PSR...TWC...

ATTN...RFC...STR...NWC...

LAT...LON   34561110 34441041 33840945 32840904 31770912=20
            31230956 31181081 31571162 32221201 32991225=20
            33671232 34401195=20

=3D =3D =3D
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