641
FXUS65 KTWC 301526
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
826 AM MST Thu Jul 30 2026

.SYNOPSIS...Expect a downturn in thunderstorm activity today and
Friday with just isolated storms south and east of Tucson. Storm
coverage and chances increase this weekend into next week. High
temperatures will be 10-15 degrees above normal today into the
weekend with an Extreme Heat Warning in effect through Sunday.

&&

.UPDATE...Some residual cloudiness moving northward across our
forecast area this morning. Latest visible satellite imagery trends
show clouds are gradually diminishing. Main story for today will
continue to be the extreme heat, with overall storm coverage below
normal for late July. Main areas to watch for the afternoon and
evening will be south and east of Tucson, especially Cochise County
as that area is most favorable and there will also be a potential
MCS in Sonora this evening that could extend northward into Cochise
County as well. Gusty winds and locally heavy rain will occur with
any storms that occur. HRRR is by far the most aggressive of the
CAMS in trying to show scattered storms further north and west into
the Tucson area and even onto the T.O. Nation later this afternoon.
The rest of the HREF members and UofA WRF generally limits storm
activity to locales south and east of Tucson. Made a few minor
tweaks to the PoPs for Cochise County this afternoon but overall the
forecast is in good shape. See previous discussion below for
additional information.



&&

.DISCUSSION...IR Satellite shows a decaying MCS over Sonora
with clouds along its northern edge reaching the international
border. Aloft, high pressure is centered over New Mexico and
will build westward while strengthening today into Friday. This
will lead to the hottest temperatures of the year so far for
southeast Arizona. NAEFS mean 500 mb heights will be 3-4
standard deviations above normal during this time period with
Saturday likely being the hottest days. High temperatures from
Tucson westward will range from 108-113 Saturday afternoon. NBM
probabilities for Tucson International to reach 110 degrees or
higher are 15 percent today, 50 percent Friday, 75 percent
Saturday, and 40 percent Sunday. These temperatures will lead to
areas of Major to Extreme HeatRisk, which means anyone without
adequate means of cooling will be affected by the heat. An
Extreme Heat Warning is in effect today through Sunday.

The placement of the ridge the next couple of days along with a
small loss in moisture will be less than ideal for thunderstorm
development. Storm coverage and chances will be reduced today
and Friday with just isolated storms along the international
border, AZ/NM border, and the White Mountains. Although the MCS
to the south may send an outflow northward that could help
storms along the international border. This weekend storm
coverage and chances increase to cover more of Cochise and
Graham Counties with PoPs generally 20-50 percent south and east
of Tucson.

After Sunday the ridge weakens, but will still have positive
height anomalies, and becomes centered over the Four Corners or
AZ/UT border. This will be more favorable for thunderstorm
activity and will lead to an uptick in monsoon activity Monday
into next week. Expect daily afternoon and evening thunderstorms
from central Pima County eastward Monday into at least the
middle of next week. Ensembles also hint at enhanced mid-level
flow with mean 500 mb winds ranging from 20-30 kts Monday and
Tuesday, which could lend upper level support to storms. Also,
with the heights decreasing slightly temperatures also begin to
"cool", but will still be 2-7 degrees above normal next week.

&&

.AVIATION...Valid through 31/12Z.
BKN clouds AOA 18k ft AGL this morning from KTUS south becoming
SCT-BKN 8k-12k ft AGL this afternoon and evening south and east
of KTUS. Isolated TSRA will be possible 30/21Z-31/03Z with KDUG
terminal having the best chance to be impacted by TSRA. KOLS
could see TSRA as well, but confidence is lower. Near
thunderstorms wind gusts up to 35 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 through Sunday with an Extreme Heat Warning in place
today through Sunday. 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 through Saturday then 15-30 percent Sunday into
next week. Winds will be terrain driven 5 to 10 mph.

&&

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

&&

$$

Update...GL
Discussion...Hardin

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