804
FXUS65 KTWC 282145
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
245 PM MST Fri Aug 28 2026

.SYNOPSIS... Expect daily afternoon and evening thunderstorms
through at least Monday. After Monday storm chances begin to
decrease. High temperatures will remain well above normal through
Saturday with an Extreme Heat Warning in effect for much of
southeast Arizona. Temperatures are forecast to fall to near normal
Sunday through early next week.

&&

.DISCUSSION...
Cloud remnants are continuing to dissipate across Western Pima
and Southeast Pinal counties early this afternoon. Areas that
were able to clear out early this morning and warm up (Santa
Cruz, Cochise, Graham, and Greenlee Counties) are beginning to
have towering cumulus and storm development in the mountains.
Storms this afternoon and evening continue to look more limited
in intensity and coverage than yesterday, with strong wind gusts
40-50 mph and isolated flash flooding.

Looking toward the weekend, the uptick in thunderstorm activity
is still on track. The current high pressure will begin to move
eastward as an area of low pressure digs down and passes through
the Great Basin. With this pattern, a broad area of ascent
ahead of the trough in combination with some embedded
shortwaves will allow for thunderstorms beginning late Saturday
afternoon and continuing on and off through Sunday night. The SW
flow will draw in additional moisture with PWs increasing to
1.3 to 1.7 inches across Southeast Arizona. The 29/12Z HREF run
is showing the potential for storms to be capable of producing
rainfall rates of 1-3 inches per hour. Additionally, many CAMs
like the U of A WRF, HRRR, NAM, and RAP are showing thunderstorm
activity continuing overnight. With the combination of the
increase in moisture, overnight thunderstorm potential, and
generally faster response times, a Flash Flood Watch has been
issued for Saturday and Sunday. Excessive rainfall may result in
flooding of rivers, creeks, streams, and other low-lying and
flood-prone locations. Low-water crossings may be flooded.
Flooding may occur in poor drainage and urban areas.

After Monday troughing stays in place to the west and over the
Pacific Northwest keeping Arizona under southerly to
southwesterly flow. Moisture values stay slightly above normal,
but storm chances decrease as a more transitional monsoon
pattern sets up. Still expect daily afternoon and evening
thunderstorm chances but coverage will likely be reduced with
the best chances along the international border. Temperatures
also decrease to around normal Sunday into the middle of next
week.

&&

.AVIATION...Valid through 30/00Z.
Isolated to scattered SHRA/TSRA 28/20Z through 29/03Z. Thunderstorms
will have the potential for strong wind gusts, otherwise surface
winds will be southwest to south 5 to 10 kts through the afternoon,
then light and terrain driven overnight. Ceilings becoming SCT-BKN
8k-12k through the afternoon then diminishing in coverage overnight.
More widely scattered showers and thunderstorms expected Saturday
afternoon and evening, especially through KOLS-KTUS. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...
Isolated to scattered thunderstorms this afternoon, with an active
period expected through Monday (30 to 70 percent daily thunderstorm
chances). Temperatures will remain well above normal today with a
cooling trend this weekend into early next week. Minimum relative
humidity values mainly 10 to 20 percent in the valleys and 20 to 30
percent in the mountains today. Minimum RH values increase to 20 to
40 percent starting Saturday in valleys and 30 to 50 percent in the
mountains. Winds will generally remain less than 15 mph and terrain
driven through the week.
&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning until 8 PM MST Saturday for AZZ501>509.
Flood Watch from Saturday morning through late Sunday night
for AZZ502>507-513>515.

&&

$$

DISCUSSION...JT
AVIATION...Edwards
FIRE WEATHER...JT

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