Severe Thunderstorm Warning 71, NWS Tucson, AZ

Area Forecast Discussion
National Weather Service Tucson AZ
916 AM MST Fri Sep 12 2025

.SYNOPSIS...Scattered afternoon and evening thunderstorms will
continue today mainly from Tucson south and eastward. Gusty
winds, brief heavy rain, blowing dust and lightning will be the
main hazards. High temperatures will be a few degrees below
normal through Saturday, then warm back to normal or a few degrees
above normal. There will be a slight chance of thunderstorms
southeast of Tucson on Saturday and dry conditions areawide
Sunday. Temperatures warm back up a couple of degrees next week,
along with a return of slight chances of afternoon and evening
thunderstorms.

&&

.UPDATE...

Early morning convection continues on the leading edge of an upper
level jet, associated with the deep trough sitting over southern
California through northern Baja. Recent radar imagery has shown
signs of mid-level rotation within these storms, indicative of
moderate deep layer shear present with the incoming trough and
stronger flow aloft. While these morning thunderstorms should
remain sub-severe, increasing instability over the next several
hours should allow for more widely scattered thunderstorms to
develop with an isolated severe threat and the possibility of
hail, damaging wind gusts, and heavy rainfall. This morning's
satellite derived precipitable water products (especially Advected
Layered Precipitable Water (ALPW)) show that the healthiest mid-
level moisture for greater thunderstorm coverage remains through
Cochise, Graham, and Greenlee counties. However, the 700-500mb
ALPW precipitable water imagery depicts a westward shift over the
previous 24 hours in its western edge through Dudleyville,
Tucson, and down through Nogales. Yesterday afternoon this
gradient sat just on the east side of Tucson which is where the
heaviest convection ended up as well. It seems reasonable then
given this westward shift in healthier mid- level moisture that
Tucson will have a better opportunity at convection this
afternoon-evening. That said, the southwest to northeast oriented
flow will keep thunderstorm motion moving away from Tucson and any
Tucson impacts will likely require thunderstorm initiation to
occur west/southwest of town. This morning's high- resolution
guidance paints a similar picture with likely chances through the
eastern counties (40-65 percent chance) and the gradient sitting
over central to eastern Pinal, Pima and through Santa Cruz
counties (20-40 percent chance).

&&

.PREV DISCUSSION... /issued 207 AM MST Fri Sep 12 2025/ Water
vapor imagery shows a trough centered over the Great Basin and
high pressure centered over Texas. This has resulted in a mid-
level moisture gradient across southeast Arizona with above normal
PWATS east of Tucson and below normal PWATs west of Tucson.
Tucson moisture levels are right around normal. Because of this
expect similar thunderstorm coverage to yesterday. Hi-res guidance
shows scattered to numerous thunderstorms south and east of
Tucson with Tucson again on the western edge of activity. Storms
will be aided by the approaching trough which increases 500 mb
winds to 30-35 kts. This could lead to some storms seeing strong
and sustained updrafts which could lead to heavy rainfall and
strong outflow winds. The 12/00Z HREF does show the possibility
for a rotating storm or two east of Tucson this afternoon. Storms
will likely be moving fast which could cut down some on the flash
flooding threat, but will still be something to watch. Overnight
the trough moves through northern Arizona and southern Utah. This
could lead to some overnight convection which is supported by some
members of the HREF. The bulk of this overnight activity looks to
be mainly over Graham and Greenlee Counties.

Saturday with the trough being further east the dry air will also
be further east. Above normal moisture will be confined mainly to
Cochise County. As a result storm coverage will be less than the
past couple days with the best chances in Cochise County and the
AZ/NM border. Sunday looks to be dry thanks to the trough scouring
out moisture as it exits the region. This is a typical
transitional pattern for this point in the monsoon. Temperatures
will be below normal through Saturday, then rebounding to around
normal or a few degrees above normal thereafter.

Next week high pressure sets up to the south and east which will
allow some moisture to filter back into southeast Arizona. This
will lead to rain chances south and east of Tucson with the best
chances along the international border and the White Mountains
through mid next week. Right now Tuesday looks to be the best day
for rain chances with NBM PoPs 20-40 percent.

&&

.AVIATION...Valid through 13/12Z.
SCT-BKN clouds at 8k-12k ft AGL aft 12/17Z. Scattered
-SHRA/-TSRA mainly east of KTUS-KOLS-KCGZ line thru 13/04Z. KDUG
 and KSAD terminals have the best chances to see TSRA. Gusty and
 erratic winds to 45 kts possible with any thunderstorm.
 Otherwise, SLY/SWLY SFC wind at 10-16 kts with gusts to 20-25 kts
 thru 13/04Z. SFC wind less than 10 kts and variable in direction
 at other times. Aviation discussion not updated for TAF
 amendments.

&&

.FIRE WEATHER...Minimum RH values will be in the 20-35 percent range
through Saturday, lowering into the 15-30 percent range Sunday and
Monday. Scattered showers and thunderstorms are expected from the
Tucson area eastward today, with a chance of showers and
thunderstorms mainly for Cochise County and east Santa Cruz
County Saturday. Dry area-wide Sunday, then a slight chance of
thunderstorms south and east of Tucson return again next week.
Gusty and erratic winds are expected with thunderstorms. Outside
of thunderstorm outflows, expect 20-foot winds to be 15 mph or
less, with some afternoon/early evening gusts to around 25 mph.

&&

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&

Update...Edwards

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Preliminary Local Storm Report
National Weather Service Tucson AZ
836 AM MST Fri Sep 12 2025

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0401 PM     Flash Flood      2 NE Benson             31.98N 110.27W
09/11/2025                   Cochise            AZ   Public

            Social media report of stuck cars on
            Pomerene Rd due to flash flooding.

&&

AJE