Weather alerts for the NWS Tucson AZ forecast area

000
FXUS65 KTWC 281036
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
336 AM MST Wed Oct 28 2026

.SYNOPSIS...

Dry conditions are expected across Southeast 
Arizona into Thursday. Scattered showers and thunderstorms will 
return to the region Friday, followed by a lull in storm 
activity Saturday, then widespread showers with scattered 
thunderstorms Sunday into Monday. Areas of moderate to heavy 
rainfall will be possible Friday and especially Sunday. 
Afternoon high temperatures will be a couple of degrees above 
normal today and Thursday, then lower below normal Friday into 
early next week. 

&&

.DISCUSSION...

Upper level flow will turn southwesterly today, directing high
level clouds over southeastern Arizona while keeping
temperatures 1-4 degrees above normal. This upper level wind
shift is part of the beginning of a pattern evolution that will
see an eastern Pacific trough deepen and carry a sub-tropical
jet over the region through the end of the week. A poleward push
of unseasonably moist air will arrive with this jet, bringing
10-20 percent chances for showers and thunderstorms to eastern
Graham, Greenlee, and Cochise counties Thursday afternoon and
evening. The moisture plume will then overspread the region on 
Friday, with precipitable water values exceeding 1 inch in some
areas (around the 99th percentile climatologically for this 
time of year). With southeastern Arizona under the favorable 
left exit region of the sub-tropical jet, chances for showers 
and thunderstorms are forecast across the area, especially from
northern Pima through Pinal and Graham/Greenlee counties. In 
these areas guidance has been consistent on the potential for 
greater rainfall amounts as repeated rounds or training 
thunderstorms may produce a flash flood threat. Flooding 
potential will depend on how well instability can develop during
the day, which will also impact a low end but non-zero severe 
thunderstorm threat. With effective shear of around 20-25 kts 
and MUCAPE potentially exceeding 1000 J/kg, heavy rainfall 
rates, isolated strong gusty winds, and small hail may accompany
any thunderstorm Friday. 

Saturday will mainly be between precipitation rounds as a deeper
Pacific trough makes its way towards the region. Atmospheric
moisture will remain on the higher side on Saturday so while
notable precipitation chances aren't forecast, isolated
afternoon/evening showers can't be ruled out.

A more potent mid-level shortwave and jet streak is expected to
cross southern California and then Arizona Sunday into early 
Monday. Impressive synoptic forcing combined with a plume of 
1-1.5 inch PWATs will bring widespread rain with isolated 
embedded thunderstorms, starting in the west/north Sunday 
morning and moving into southeastern areas through the 
day. The combination of the upper level wave and moisture plume
will be notable as precipitable water values will be pushing 
record levels for this time of year. In NAEFS climatology, 
precipitable water and integrated water vapor transport values 
range from the 99th percentile to the max of climatology, 
highlighting the potential significance of this event. 
Instability may be hard to come by with widespread cloud cover 
and while this may somewhat temper short term precipitation 
rates, longer duration periods of moderate to locally heavy 
rainfall rates will still likely cause flows in normally dry 
washes and water across roadway dips and other low-water
crossings. Ensemble model probabilities for rainfall range from
0.5-1 inches across southern locations mainly south of I-10, to
1-2 inches north through Pinal, Graham, and Greenlee counties
into central Arizona. These probabilities are greatest in 
higher terrain from the Catalinas/Rincons northeast through the 
White Mountains. Rainfall totals pushing 3 inches can't be ruled
out along southwest oriented slopes of this higher terrain. 
Along with a flash flooding potential, more substantial flows 
may develop in creeks and rivers of northern Graham and Greenlee
counties, including the San Francisco, Blue, and Gila rivers. 
Depending on the magnitude and placement of the heaviest 
rainfall, impacts within these watersheds could continue into 
early next week. 

The moisture feed will have likely exited the region by Monday
morning, but lingering moisture and cyclonic flow aloft will
keep a non-zero chance of a lingering shower during the day. 
Temperatures are expected to fall well below normal Sunday and
Monday with some warming but still remaining below normal into 
mid- week.

&&

.AVIATION...Valid through 29/12Z. 

Initially SKC then increasing cirrus AOA 20k ft. Surface wind 
less than 10 kts and following normal diurnal patterns through 
the TAF period. Aviation discussion not updated for TAF 
amendments.

&&

.FIRE WEATHER...

Dry conditions are expected across Southeast 
Arizona into Thursday. Scattered showers and thunderstorms will 
return to the region Friday, followed by a lull in storm 
activity Saturday, then widespread showers with scattered 
thunderstorms Sunday into Monday. Moderate intensity rainfall  
with pockets of heavy rain is expected both Friday and Sunday, 
with locally heavy storm-total rainfall amounts possible, 
especially in the higher terrain. Afternoon high temperatures 
will be a couple of degrees above normal today through Thursday,
then lower below normal Friday through the weekend. 20-foot 
winds will generally be 15 mph or less through Thursday. Breezy 
southerly winds are anticipated Friday, with breezy to locally 
windy southwest winds expected Sunday, turning northwest Monday.
Minimum RH values will be in the 15-25 percent range today and 
Wednesday. Minimum RH levels will increase late in the week and 
over the weekend, with values at 40+ percent.

&&

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

&&

$$

SYNOPSIS...
DISCUSSION...Edwards
AVIATION...Edwards
FIRE WEATHER...Edwards

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