Severe Thunderstorm Warning 40, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
221 PM MST Sat Aug 9 2025

.SYNOPSIS...

Thunderstorm chances are forecast each afternoon and evening
through the coming week across southeastern Arizona, though there
will be day to day variability in these chances. Isolated to
scattered thunderstorms are expected to develop through this
evening, especially from Santa Cruz through Cochise County. An
isolated threat for wind gusts and heavy rain will exist with
these thunderstorms. High temperatures will generally remain
above normal through the coming week.

&&

.KEY MESSAGES...

- Isolated to scattered thunderstorms forecast today, with highest
  coverage across Santa Cruz through Cochise County. An isolated
  threat for damaging wind gusts and flash flooding will accompany
  these thunderstorms.

- Daily chances for thunderstorms will continue through the coming
  week with day to day variability in chances.

- High temperatures will likely remain a few degrees above average
  through the coming week.

&&

.DISCUSSION...

With the center of an upper level high from eastern Arizona into
New Mexico, southeasterly flow in the mid-levels has ushered
1-1.4 inches of precipitable water into southeastern Arizona
today. The 18Z upper air observation out of Tucson still depicts
a pocket of dry air around 700mb, with a subsidence cap between
850-700mb. This capping will likely be less of an issue further
south where moisture content is greater and terrain provides a
stronger point of initiation. Across far southeastern Arizona,
especially Santa Cruz to southern Cochise county, 1500-2000 J/kg
of MUCAPE and similar DCAPE were depicted on the SPC mesoanalysis
page this afternoon. This combination of instability parameters
highlights a threat for severe wind gusts with any stronger
thunderstorms that form, which is highlighted on SPC's Day 1
outlook. Additionally this level of precipitable water will likely
cause brief periods of heavy rain, however the flash flooding
risk is uncertain as outflows pushing out from thunderstorms will
likely cause shorter durations of heavy rainfall events. That
said, an isolated flash flood risk will be messaged. Going further
north towards the Tucson metro, coverage becomes less certain and
the aforementioned capping inversion will play a role in Tucson's
thunderstorm chances. The conditional instability depicted on the
18Z upper air observation lead to a modest bump in Tucson's
chances with this forecast package, but remains in the 30 percent
range. Thunderstorms will additionally develop off the White
Mountains and should move into Graham and southern Greenlee
counties, which may also produce a strong wind threat.

Over the coming days moisture in some sense should stick around
southeastern Arizona, leading to daily thunderstorm chances. By
tomorrow night, mean wind makes an attempt to swing around to the
north to northeast, which may cause thunderstorm chances to linger
late in the night over the next few nights as this pattern often
favors thunderstorm longevity. Otherwise day to day variability
with probabilities depending on moisture quality and previous
activity will be the reasonable expectation through the remainder
of the week.

&&

.AVIATION...Valid through 11/00Z

Isolated to scattered thunderstorms this afternoon and evening,
mainly south and east of KTUS. Gusty winds to around 45 kts
possible near thunderstorms, with an isolated chance of exceeding
50 kts. Otherwise northwesterly winds of 10-15 kts through early
evening, and 12-17 kts at KSAD with gusts up to 30 kts. Additional
thunderstorm chances possible Sunday afternoon and evening. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...

High temperatures will remain several degrees above normal through
the coming week. Daily chances for thunderstorms and wetting rains
through the week with daily variability in coverage and intensity. Min
RHs will generally be around 14-22 percent in the lower
elevations and 20-30 percent in the mountains. Winds will
generally be less than 15 mph with typical afternoon gusts up to
20 mph into the new week, though stronger northwesterly winds
possible in the Gila River Valley through early this coming week
with afternoon gusts up to 35 mph.

&&

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

Public...Edwards
Aviation...Edwards
Fire Weather....Edwards

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