131
FXUS65 KTWC 291605
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
905 AM MST Wed Jul 29 2026

.UPDATE...
Generally clear skies across Southeastern Arizona with a thin
scattered mid-to-high layer based on the latest visible
satellite imagery. There are remnants of convection south of
Bootheel which will continue to dissipate and clear in the next
few hours. This will set up for afternoon thunderstorms. 12Z
hi- res guidance shows isolated to scattered thunderstorms
forming by the early afternoon. The best locations will be in
east and south of Tucson...starting on the higher terrain...
because CAPE values will be 1000 to up to 2000 J/kg with shear
values 10-20 kts and PWATs around 1.4 inches. A few storms will
be capable to produce severe level winds and rain totals up to
an inch. Santa Cruz county has 50 percent chance for an inch or
higher, raising the risk for flash flooding. Storms will move
westerly through the afternoon and dissipating in the evening. A
few hi-res models show storms moving into the Tucson metro, but
they will be on the dissipating end of its lifecycle. See
previous discussion for other forecast details.



&&

.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...issued at 2:05 AM.
Much quieter tonight than 24 hours ago with just some mid to
high level clouds over southeast Arizona. High pressure is still
centered over northern New Mexico but will move further west
and strengthen Thursday into Friday. PWAT values are right
around normal for this time of year and will remain that way
through the weekend.

Today looks to be a bit more active than Tuesday with hi-res
guidance showing scattered convection south and east of Tucson
this afternoon and evening. A couple HREF members show isolated
activity over Tucson, but the metro and central Pima County will
likely be on the western periphery of storm chances. CAPE values
will be around 1000 J/kg with modest 0-6 km shear of 15-25 kts
from Tucson eastward. Expect normal monsoon hazards with some
storms capable of severe wind gusts thanks to the wind shear.
Locally heavy rainfall will also be a threat with HREF and REFS
showing the southern half of Cochise County seeing the best
chances for heavy rain.

Thursday into Friday the ridge begins to move westward into
Arizona and may suppress storm activity. Surface moisture also
decreases slightly both days with dewpoints dropping into the
low 50s. Expect isolated activity both days mainly along the
AZ/NM border and the White Mountains. The main story will be the
very hot temperatures. Highs will run 7-12 degrees above normal
Thursday through Sunday with Tucson seeing a good chance to hit
110 degrees for the first time this year. NBM probabilities for
110 degrees or higher at Tucson international are 15 percent
Thursday, 55 percent Friday, 70 percent Saturday, and 40 percent
Sunday. These temperatures will lead to Major and Extreme
HeatRisk and an Extreme Heat Warning is in effect Thursday
through Sunday.

This weekend storm chances slowly increase in coverage, but the
best chances will still be to the south and east of Tucson. This
trend continues into early next week with the potential for an
uptick in thunderstorm activity as the ridge decreases sightly
in strength and becomes centered closer to the Four Corners.

&&

.AVIATION... Valid though 30/12Z.
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. Near thunderstorms wind gusts 30-40 kts will be
possible. Surface winds variable less than 8 kts this morning
becoming NWLY 6-10 kts with occasional gusts this afternoon and
evening. 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
20-35 percent in the lower deserts today dropping to 15-25
percent Thursday 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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