911
FXUS65 KTWC 241623
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
924 AM MST Sun Aug 24 2025

.SYNOPSIS...Shower and thunderstorm chances continue west of
Tucson today, then expand to the remainder of southeast Arizona
starting Monday. Expect daily chances for showers and
thunderstorms with day to day variability on coverage and
intensity this week. Above normal temperatures through Monday
then trending down to slightly below normal Tuesday through
Thursday. An Extreme Heat Warning in effect until this evening
for the greater Tucson area to southeastern Pinal county.

&&

.UPDATE...Mostly sunny skies this morning across southeast Arizona.
The situation is similar to yesterday with much drier conditions
from Tucson south and eastward east of Tucson (PWAT 0.6 inch to 1
inch) with wetter conditions across central and western Pima County
(PWAT 1.25 to 1.5 inches). Latest CAMs/HREF are in good agreement on
developing convection this afternoon from Sells westward. Can`t rule
out a severe thunderstorm especially across western Pima County
where the HREF highlights 40-km neighborhood probabilities of 10-30%
of wind gusts greater than 50 mph. Some locally heavy rain is also
expected with stronger storms for the western deserts. As additional
moistures moves to the north and east tonight and overspreads more
of our forecast area, some storms have the potential to linger into
the overnight and early morning hours as well, especially across the
western deserts. Current forecast in good shape this morning. No
updates.

&&

.DISCUSSION...Clear to partly cloudy skies prevailed this morning
with upper high near the 4 corners. The area continues to be split
in half with PWATs in the 0.50" to 0.75" range east of Tucson and
moister atmosphere with values up 1.50" west of Tucson. Surface
dewpoints this morning were in the 40s east of Tucson, near 60 in
and around Tucson, and from the mid 60s to mid 70s across western
Pima county. As was the case yesterday, the main focus for widely
scattered thunderstorms this afternoon/evening will be across W-SW
of Tucson. Once again the main threats in this area will be
strong gusty winds and brief heavy rain. Can`t rule out a severe
thunderstorm or two later today west of Sells with 24/00z HREF
showing 10%-30% neighborhood probabilities of winds greater than
50 kts. On temperature side, an Extreme Heat Warning remains in
effect for portions of eastern Pima and SE Pinal Counties.

Monday is trending to be a very active day across most of Pima
county and Santa Cruz county as an approaching 300 mb trough from
the SW brings increasing divergent flow out ahead of it while the
deeper moisture that is residing west of Tucson today spreads
east during the day. Latest model guidance is showing scattered
strong, isolated severe, thunderstorms some of which will be
producing very heavy rain with possible 1"+ rainfall rates/hr
increasing the flash flooding threat. Area of concern would be
south of a Ajo to Nogales line. Current WPC ERO has marginal risk
(5%) of rainfall exceeding flash flood guidance.

Tuesday: South-southwest flow aloft with an upper trof to our
west and the upper high over Texas. Areal coverage of storms may
shift to across the eastern half of the forecast area as the
western part may be worked over from Mondays action.

Plenty of uncertainty after Tuesday as deeper southwest flow aloft
may push drier air across the area. The pattern we`ve seen as the
area has been unable to hold and maintain deep monsoonal moisture
across the area for an extended period of time. Confidence low
after Tuesday.

Temperatures will cool down to below normal levels starting
Tuesday through Thursday then warmup a bit next weekend.

&&

.AVIATION...Valid through 25/12Z.
SCT lcly BKN 9k-12k ft AGL. WDLY SCTD -SHRA/-TSRA west of KTUS
btwn 24/19z and 25/03z. Expect gusty and erratic winds with any
-TSRA otrw SFC winds will generally be E-SE less than 12 kts
through the fcst pd. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Expect daily chances for rain showers and
thunderstorms this week with day to day variability of intensity
and coverage of storms. Temperatures will be running above normal
again today with an Extreme Heat Warning in effect for the lower
elevations. Winds will generally remain less than 15 mph with the
afternoon gustiness into next week. Min RHs will be 15-20 percent
in the low elevations and 20-30 percent in the mountains through
the weekend. Deep monsoon moisture will early this week to provide
higher wetting rain chances and coverage as well as better min
RHs and below normal temperatures.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
 Extreme Heat Warning until 8 PM MST this evening for AZZ504>506.

&&

$$

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