Severe Thunderstorm Warning 77, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
1236 PM MST Wed Jul 29 2026

.SYNOPSIS...
Expect daily afternoon and evening showers and
thunderstorms through the weekend with day to day variability
in coverage and strength. High temperatures will warm to 7-12
degrees above normal Thursday into the weekend with an Extreme
Heat Warning through Sunday.

&&

.DISCUSSION...
GOES sounder profile and SPC mesoanalysis shows the atmosphere
eroding the last remaining CIN values across the area. There
has been ample sunshine to continue eroding CIN and there are a
few towering cumulus clouds forming over the eastern Sky
Islands. All indications for an active afternoon for areas south
and east of Tucson. These areas have the best ingredients to
support thunderstorms due to shear values of 10-20 kts and CAPE
greater than 1500 j/kg. A few storms will reach Tucson metro to
bring gusty winds and light to moderate rain showers. 12Z HREF
model has 70% chances for wind gusts greater than 35 mph in
Cochise County and into eastern Santa Cruz County this
afternoon. There can be a few storms capable producing a severe
level wind in the afternoon. Storm's will be capable producing
up to 0.75-1 inch total with Santa Cruz County having at least
50% of receiving an inch or more through the late evening.
There will be a risk for flash flooding along the International
Border between Nogales and Naco.

The ridge of high pressure will start to build west starting
tomorrow. Temperatures will be increasing 10-15 degrees above
seasonal normals. This will push the region into Major and
Extreme HeatRisk tomorrow through Sunday. The hottest days will
be Friday and Saturday with temperatures reaching up to 113F.
Tucson has 112F on Saturday. Extreme Heat Warning is in effect
Thursday through Sunday evening.

Thunderstorm chances will be generally low tomorrow and Friday
due the lack of upper level support. There will be plenty of
instability to get vertical growth. The best areas for any
thunderstorm growth will be south and east of Tucson. Chances
will increase for Saturday and Sunday.

Next week, right after this heat, the upper level flow will
return from the east to southeast with the high pressure center
close to the Four Corners. This set up will provide better daily
chances for thunderstorms and rain showers.

&&

.AVIATION...valid through 31/00Z.
SCT clouds AOA 15k ft AGL this morning becoming SCT-BKN 8k-12k
ft AGL this afternoon and evening south and east of KTUS.
Isolated to scattered TSRA will be possible 29/20Z-30/03Z with
KOLS and KDUG terminals having the best chances to be impacted
by TSRA. KTUS has a 10 percent chance for TSRA. Near
thunderstorms wind gusts 30-40 kts will be possible. Surface
winds NWLY 6-10 kts with occasional gusts this afternoon and
evening and again after 30/18Z. In the overnight hours, winds
will be less than 10 kts and variable. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...
High temperatures will remain well above normal
this week with an Extreme Heat Warning in place Thursday
through Saturday. Expect daily chances of afternoon and evening
showers and thunderstorms mainly south and east of Tucson
through the weekend with some day to day variability in
coverage. Early next week storm coverage and chances are
expected to increase. Any thunderstorm will bring a threat of
severe, erratic wind gusts as well as brief heavy rainfall and
an isolated threat of flash flooding. Min RH values will
be 10-20 percent tomorrow into the weekend. Winds will be
terrain driven 5 to 10 mph.

&&

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

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