Severe Thunderstorm Warning 50, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
133 PM MST Thu Aug 21 2025

.SYNOPSIS...Daily chances for thunderstorms and rain showers for
Southeast Arizona with day to day variability on coverage and
intensity. Above normal temperatures through the weekend and then
trending down to near normal by the start of the new week. An Extreme
Heat Warning in effect today through Friday and a Blowing Dust
Advisory is in effect today from 4 PM to 9 PM this evening.

&&

.DISCUSSION...A field of cumulus clouds have developed across the
region some beginning to tower. Due to the location of high
pressure, storms and showers will initiate along the higher
terrain and move west to southwest across the region. Cochise
County will have drier air, leading to lower chances for rain
showers and thunderstorms. The 12Z HREF shows there is a 10%
chance for 50kt winds this afternoon and with the 18Z sounding
launched at TUS showing 1200 J/kg DCAPE, the main concern with
thunderstorms this afternoon is strong outflow winds and blowing
dust. There is a Blowing Dust Advisory for the area between
Tucson and Phoenix along I-10 from 4 PM to 9 PM this evening.
Expect visibilities to drop between 1/4 to 1 mile in blowing
dust. The Extreme Heat Warning is still in effect today through
tomorrow evening for the lower elevations of most of southern
Arizona. Remember to stay hydrated and spend time indoors with
A/C. If you need to spend time outside, wear light weight, light
colored clothing and take frequent breaks. Take time to learn the
signs of heat exhaustion and heat stroke, keeping in mind that
heat stroke is an emergency.

The Four Corners high will continue to influence the region. The
high now oval shaped, is bring northeasterly flow across
Southeastern Arizona. Heat is still a concern through tomorrow as
low elevations will be above 100 degrees to 110 degrees with
little overnight reprieve. Those areas will experience Major
HeatRisk to isolated areas of Extreme HeatRisk through Friday. We
will be trending down slightly in temperatures this weekend but
areas will be on the cusp on Major HeatRisk per climatology.
Overnight temperatures will continue to be high with widespread
Major HeatRisk overnight.

By the weekend, dryer air will push more into the region, but
there will be enough instability and moisture to give daily
chances. Higher terrain will naturally be the better areas for
those rain chances. The Four Corners High will transform itself to
ridge through the Great Basin by the start of the new week. Plus,
troughiness will develop near the Pacific coast. This will open
up southeasterly to southerly flow of deep monsoon moisture back
into the region. Ensemble models show our PAWTs shooting up to
1.4-1.6 inches at Tucson with higher values towards Yuma. This
tongue of moisture will provide better chances and coverage for
rain showers and thunderstorms. As of this forecast, Tuesday
through Wednesday appear to be the wettest days in the forecast
period. Increase moisture will lower our temperatures and leaning
below normal through the new week.

&&

.AVIATION...Valid through 23/00Z.

FEW to SCT clouds AOA 7k to 10k ft AGL with across the region. By
Isolated to scattered -SHRA/-TSRA forming along the higher
terrain and moving westward from 21/22 through 22/06Z. Lingering
-SHRA is possible through 22/10z. SFC winds will generally be
easterly- southeasterly less than 12 kts through the forecast
period. Expect gusty and erratic winds with any -TSRA. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Expect daily chances for rain showers and
thunderstorms into the new week. Dryer air will be moving into the
region to create day to day variability of intensity and
coverage. Temperatures will be running above normal through the
weekend with an Extreme Heat Warning in effect through Friday in
the lower elevations. Winds will generally remain less than 15 mph
with the afternoon gustiness into the new week. Min RHs will be
15-20 percent in the low elevations and 20-30 in the mountains
through the weekend. Deep monsoon moisture will return early next
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 Friday for AZZ501>507-509.

Blowing Dust Advisory from 4 PM this afternoon to 9 PM MST this
evening for AZZ502-504>506.

&&

Malarkey/ Strongman

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