257
FXUS65 KTWC 221621
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
921 AM MST Sat Nov 22 2025

.SYNOPSIS...An active pattern continues through this weekend as
another weather system arrives late today through Sunday bringing
rain and cooler temps. Precip chances begin in western Pima
County this afternoon expanding to cover all of southeast Arizona
this evening through the overnight hours. Sunday precipitation
chances decrease from west to east. High temps cool to below
normal Sunday and Monday, then begin a warming trend through the
end of the week.

&&

.UPDATE...Water vapor imagery this morning showed that the closed
upper low near Guadalupe Island NW of the Baja Spur has bottomed
out. Cloud cover has been slowly increasing and creeping east
across Pima and Pinal counties with any shower activity occuring
across parts of Yuma county. PWATs this morning ranged from 0.30"
near AZ/NM border to near 0.60" across wrn Pima county with
increases likely into this evening.

The closed upper low will start to lift NE toward nrn Baja later
this morning and be over nrn Baja this afternoon and lift across
southern Arizona this evening. Initial shower activity will start
across wrn Pima county between 11 am and 1 pm with showers and
possibly a thunderstorm or two developing across Pinal county,
remainder of Pima county and Santa Cruz county between 1 pm and
5 pm. Scattered to widespread showers and isolated thunderstorms
area wide between 5 pm and 11 pm. Some of the thunderstorms may
produce small hail, thanks to -20C mid-level temps, and wind gusts
up to 40 mph. In addition, with PWATs expected to be up around
0.90" or over 200% of normal later this afternoon into this
evening, a few of the showers or thunderstorms will have brief
heavy rain with potential rainfall rates over 1"/hour that may
produce some brief flooding issues. In collaboration with WPC,
portions of southeast AZ was put in marginal risk for Excessive
Rainfall. On the snow side, snow levels this morning are above the
mountain peaks put expected to lower down to 8000 feet tonight.
Convective nature of storms may briefly bring levels down to 7500
feet after 8 pm. My concern is Mt Lemmon area in the Catalina
mountains where snow rates for a brief period of time may be 1"-2"
per hour. Right now holding off on issuing Winter Weather
advisory. Will run out a quick forecast update based on latest
trends.

&&

.PREV DISCUSSION... /issued 214 AM MST Sat Nov 22 2025/
A closed low is centered off the northern coast of Baja with
moisture streaming into Arizona out ahead of it. The low will
slowly move onshore today passing through Arizona tonight into
Sunday morning. Shower activity is currently ongoing over southern
California and will spread eastward in to Arizona as the low
moves onshore. Ahead of the precip winds will be breezy with gusts
25-35 mph from Tucson eastward. Hi-res guidance shows
precipitation moving into far western Pima County between noon and
1 PM MST, reaching Tucson around 5 PM, then encompassing all of
southeast Arizona during the evening and overnight hours.
Initially the precipitation will be all rain with isolated
embedded thunderstorms possible during the evening and overnight
hours. As the core of the low moves through Arizona Saturday night
snow levels drop to around 7500-8000 feet. Isolated to scattered
activity continues Sunday morning then dissipates from west to
east in the afternoon. Rainfall totals in the valleys are expected
to be 0.15"-0.75" with the highest totals likely in Pinal County
and the northern half of Graham County, which will see the best
synoptic scale lift on the low`s current trajectory. Up to an inch
of liquid will be possible in the mountains. With the initial
warm air mass snow totals will be on the lighter side generally
1"-2" in the Catalinas and 2"-6" in the Pinaleno and White
Mountains above 7500-8000 feet. The bulk of the precip is expected
to fall this evening and during the overnight hours. Flash
flooding is not expected but area washes and drainages will be
running.

By Sunday evening rain chances will be below 10 percent as the
low moves into Colorado. Temperatures today will be around normal
cooling to 5-10 degrees below normal Sunday into Monday. Freezing
temperatures likely return for areas south and east of Tucson
each morning Monday into the middle of next week. In the wake of
the low ridging builds in which will lead to a warmup after
Monday. High temperatures warm to just below normal Tuesday then a
few degrees above normal through the end of the week. Next
weekend into early next week ensembles show another Pacific trough
potentially moving through, which could bring another round of
precipitation and cooler temperatures.

&&

.AVIATION...Valid through 23/12Z.
SCT to BKN clouds AOA 12k ft AGL after 22/14Z. After 22/21Z
clouds become BKN 4k-8k ft AGL through the end of the period.
Scattered -SHRA will be possible at KTUS and KOLS starting around
22/23Z expanding to KDUG by 23/03Z. Isolated embedded
thunderstorms will be possible during the evening and overnight
hours. SFC winds will generally be from the southeast at 5-10 kts
through 22/16Z increasing to 10-15 kts gusting 20-25 kts at KTUS,
KSAD, and KDUG and up to 30 kts at KOLS through 23/02Z. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...A weather system will be moving through today and
Sunday bringing precipitation and breezy winds. Rain chances
begin this afternoon into the overnight hours with the bulk of any
rainfall occuring this evening and overnight. Embedded
thunderstorms will be possible. Light mountain snow will also be
possible tonight above 7500 feet. Shower activity decreases from
west to east on Sunday. Late this morning into the early evening
20 foot winds will be out of the south southeast 12-18 mph with
gusts up to 30 mph mainly south and east of Tucson. The low will
usher in below normal temps Sunday and Monday, then a warming
trend takes over. Min RH will be 30-60 percent through Tuesday,
dropping to 20-30 percent thereafter.

&&

&&

.TWC WATCHES/WARNINGS/ADVISORIES...None. &&

$$

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