306
FXUS65 KTWC 160844
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
144 AM MST Sun Aug 16 2026

.SYNOPSIS...The combination of drier-air and a more stable
atmosphere aloft will limit thunderstorm activity across
Southeast Arizona to areas mainly along and near the Arizona
and New Mexico state line, especially along over the higher
terrain. Hot conditions will return this week with an Extreme
Heat Warning in effect for portions of Southeast Arizona Monday
though Friday. Otherwise, a more active thunderstorm pattern
will return the second half of the upcoming week.

&&

.DISCUSSION...The upper pattern this morning is defined by a
ridge of high pressure centered over far ERN Texas, a distinct
inverted trough centered near the Big Bend of SW Texas and a
developing high center developing over Sonora Mexico. The inverted
trough looks impressive on WV imagery this morning with a
movement taking it toward SRN New Mexico today. As this shift
happens, it will promote the upper-high over Sonora Mexico to
strengthen with a weak col in the upper-flow developing along
the Arizona/New Mexico border. The latest GOES precipitable
water imagery indicated a dry-ish airmass across Southeast
Arizona, with PWATs 0.90-1.10 inches across Cochise/Graham and
Greenlee, 1.10-1.30 inches across SE Pinal/ERN Pima and Santa
Cruz and 1.30-1.75 inches across central and western Pima.

The best larger scale lift will occur along the AZ/NM border
today near this upper-level col. Even though the airmass is
currently dry, there is a pocket of higher PWATs 1.25-1.50
inches over northern Chihuahua Mexico and south-central New
Mexico that will advect into far SE AZ late late this afternoon
and into the evening. With this, I would expect more isolated
coverage of showers and thunderstorms, especially over the
higher terrain along the AZ/NM border. With the drier mid-
levels, I would expect these storms to only be able to produce
brief moderate-heavy rain but more capable of producing gusty
outflows to 40-45 mph. In fact, the 16/00Z HREF shows a 30-50
percent neighborhood probability of storm outflows 35+ kts in
the aforementioned area.

Otherwise, The inverted trough stalls out across the bootheel of
NM Monday but does force the upper-high center in Sonora Mexico
to lift NW into the northern Baja. As this happens, a more
favorable area of deformation aloft develops across the eastern
half of the forecast area. The airmass is still rather dry-ish
on Monday, but it should be enough to increase the coverage of
storms from isolated to widely scattered while expanding west
into ERN Pima and Santa Cruz. Heavy rainfall still is not a
major threat with these storms, but the impact of gusty winds
increases Monday. This is supported by the 16/00Z HREF
neighborhood probability of storm outflows of 35+ to 50-70
percent from Tucson northeast into Graham county.

The big weather story this week will be the return of the heat
with major HeatRisk returning to the majority of Southeast
Arizona. A Extreme Heat Warning is in effect Monday through
Friday of the upcoming week for portions of Southeast Arizona.

The upper-high center will strengthen as it slowly drifts north
during the week, eventually making its way to near Las Vegas by
21/00Z Thursday afternoon. This position will open Southeast
Arizona up to a more favorable easterly flow for thunderstorm
activity late this week into next weekend. The Monsoon season
rolls-on despite the heat.

&&

.AVIATION... Valid through 17/12Z. FEW-SCT 12-15k through 16/20Z
this afternoon, then FEW-SCT 8-12k ft AGL SCT-BKN 12-15k ft AGL
into the early evening. Isolated -SHRA/-TSRA mainly over the
higher terrain along the Arizona and New Mexico state line
between 16/22Z and 17/02Z. Gusty and erratic winds possible near
TSRA with gusts to 35-40 kts. Otherwise SFC winds light and
terrain driven through 16/20Z, then west to northwest 7-12 kts
with occasional gusts to 20 kts. Aviation discussion not updated
for TAF amendments.

&&

.FIRE WEATHER...The combination of drier-air and a more stable
atmosphere aloft will limit thunderstorm activity across Southeast
Arizona to areas mainly along and near the Arizona and New Mexico
state line, especially over the higher terrain. Hot conditions
will return this week with an Extreme Heat Warning in effect for
portions of Southeast Arizona Monday though Friday. A more
active monsoon pattern looks to return around the middle of the
upcoming week. Minimum relative humidity will generally be
15-30 percent. Outside of thunderstorms, winds will be terrain
driven around 10 mph with occasional afternoon gusts to 20 mph.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Extreme Heat Warning from 10 AM Monday to 8 PM MST Friday for
AZZ501-502-504>506-509.

&&

$$

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