Severe Thunderstorm Warning 48, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
152 PM MST Wed Aug 20 2025

.SYNOPSIS...Isolated to scattered thunderstorms this week across
Southeast Arizona, with day to day variability in intensity and
chances. The big story for Southeast Arizona will be the extreme
heat returning the second half of the week. An Extreme Heat
Warning is in effect this morning through Friday evening.

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.DISCUSSION...Mostly cloudy skies this afternoon with a field of
cumulus clouds forming across the whole area. Isolated storms and
showers have begun forming areas south and east of Tucson and
will expand to be Sells eastward as the afternoon progresses. This
is where there is substantial moisture and instability. The 18Z
upper air sounding launched at TUS shows there is 1.52 inches of
PWAT and ~1200 J/kg of DCAPE and ~1000 J/kg of MU CAPE. Storms
will be moving generally to the west- southwest at a quicker speed
indicating the main concern with storms today will be gusty
outflow winds with a secondary concern for brief, locally
moderate to heavy rainfall. Another, but equally if not more
important, weather concern for the day is extreme heat.

An Extreme Heat Warning is in effect for much of the lower
elevations in southern Arizona now through Friday evening.
Temperatures today will be around 103 to 109 degrees with Major
Heat Risk increasing tomorrow to localized Extreme Heat Risk.
Remember to stay hydrated and spend time indoors with A/C. If you
need to spend time outside, wear light weight, light colored
clothing and take frequent breaks. Take time to learn the signs of
heat exhaustion and heat stroke, keeping in mind that heat stroke
is an emergency. High pressure will keep temperatures above
normal for the rest of the week, including both overnight lows and
daytime highs. Very little reprieve for next three days. There is
a wrinkle to the heat: any storm that produces a shower or a gust
of wind will will tamp down the heat briefly or longer. It all
depends when the storm rolls through and what remains in the
heating hours of the day. Be prepared for temperatures to bounce
back up when sun pokes through the clouds after a rain shower or
thick low cloud layer.

By the weekend, the Four Corners High will shift and morph into a
ridge up through the Great Basin. This will reduce chances for
precipitation, but there will be residual moisture to provide
chances through the weekend. Temperatures will come down to near
normal by start of the new week. Troughing will start to develop
out west to shift flow into a favorable position early next week.
A southeasterly to southerly flow will be taping into tropical
moisture (or deep monsoon moisture), providing widespread chances
for wetting rain for the middle to second half of the week.
Something to look forward to after this not-so-great monsoon.

&&

.AVIATION...Valid through 22/00Z.

FEW to SCT clouds AOA 7k to 10k ft AGL across much of southeastern
Arizona. Isolated storms have begun developing near KOLS and KDUG
and will expand to become isolated to scattered from KAVQ
southward until 21/02Z. AOA 21/01Z storms and showers will develop
near KSAD moving to the southwest towards KAVQ dissipating by
21/07Z. Winds with storms will be gusty and erratic with gusts up
to 40 kts possible with any thunderstorm today. Otherwise, SFC
winds will be from the southeast at 5 to 10 kts becoming light and
variable overnight. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Expect daily chances for thunderstorms and
wetting rain showers into next week. Min RHs will generally be
15-20 percent in the lower elevations and 20-30 in the mountains.
Winds will generally be less than 15 mph with typical afternoon
gusts up to 20 mph into next week. Temperatures will be above
normal this week, with an Extreme Heat Warning in the lower
elevations of Southeast Arizona today through Friday.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning until 8 PM MST Friday for AZZ501>507-509.

&&

Malarkey/ Strongman

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