Severe Thunderstorm Warning 35, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
133 PM MST Wed Jul 30 2025

.SYNOPSIS...

Thunderstorm chances continue through the work week, with highest
chances east and south of Tucson. Chances begin to decrease
Friday as dry air pushes in through the weekend. Extreme heat is
expected Friday through the weekend.

&&

.KEY MESSAGES...

-Thunderstorm chances continue through the work week. Chances
 begin to decrease Friday as dry air pushes in through the
 weekend.

-Isolated heavy rain, strong wind gust, and blowing dust threats
 possible with thunderstorms today and Thursday.

-Extreme heat is expected Friday through the weekend. Temperatures
 remain warmer than normal through next week.

&&

.DISCUSSION...

The overall weather pattern over the Southwest US is dominated by
an expansive upper level high centered over Texas, but stretching
westward toward the eastern Pacific. Water vapor satellite
imagery is picking up on an axis of midlevel moisture associated
with vorticity stretching from the Gulf of California
northeastward through central New Mexico. As of this writing,
thunderstorms are forming along this axis, and in particular along
the White and Chiricahua Mountains and portions of Graham,
Greenlee and Cochise Counties. Today is looking to play out like a
typical monsoon day, with thunderstorms initially forming over
mountains, and becoming chaotic in nature due to outflow boundary
collisions. Storms will generally have a slow NE to SW motion
today. Some of these storms may impact Tucson or areas slightly
west getting toward the late afternoon and evening hours.
Isolated heavy rain, and strong wind gusts potentially producing
blowing dust will be the main weather threats today.

Subtle changes in the overall pattern Thursday as the center of
the upper ridge drifts westward. This will have the effect of
potentially increasing coverage of thunderstorms during the day,
with most of the forecast area having a chance of storm activity.
Storm motion looks to be even lower than today, which may tilt the
risk scale slightly more toward rain threats, though wind-related
hazards will persist.

The potential for thunderstorms begins to drop off on Friday as
the upper level ridge moves over southern Arizona, increasing
subsidence over the region. We are still carrying 20-50% chances
of thunderstorms across the forecast area Friday, with those odds
diminishing further through the weekend.

Heat replaces storm activity as the primary weather risk Friday
through Sunday as heights and thicknesses increase. Saturday
currently looks to be the hottest day of this stretch, with the
National Blend of Models highlighting a 20-50% chance of
temperatures exceeding 110 degrees, depending on location. With
the heightened HeatRisk, we have issued an Extreme Heat Warning
across much of the lower elevations for the Friday to Sunday
timeframe.

The upper ridge drifts slightly eastward again for next week,
which should allow for some moisture to return to the region.
There is a high degree of uncertainty in the details this far out
though...if moisture is limited, extreme heat may end up
persisting. The Climate Prediction Center continues to highlight
odds favoring warmer and drier than normal continuing in the 6-10
and 7-14 day periods.

&&

.AVIATION...Valid through 01/00Z.

Isolated to scattered thunderstorms possible through 31/07Z, with
cloud bases generally 9k-13k and greater coverage likely near and
east of KSAD-KOLS. Gusty erratic winds possible with any
thunderstorms. Otherwise winds mainly under 12 kts, with
occasional afternoon gusts to 20 kts. Scattered thunderstorms
possible again after 31/20Z. Aviation discussion not updated for
TAF amendments.

&&

.FIRE WEATHER...

Minimum relative humidities mainly above 25 percent east of
Tucson-Nogales, and 10-20 percent to the west. Winds mainly light
and under 12 mph, with occasional afternoon gusts. Thunderstorm
chances continue through Thursday, then a drying trend is expected
through this weekend. Forecast high temperatures remain above
normal through the weekend.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning from 10 AM Friday to 8 PM MST Sunday for
AZZ501>507-509-515.

&&

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