439
FXUS65 KTWC 271034
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
334 AM MST Tue Oct 27 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 isolated thunderstorms
Sunday into Monday. Areas of moderate to heavy rainfall will be
possible Friday and Sunday. Afternoon high temperatures will be
a couple of degrees above normal today through Thursday, then
lower below normal Friday through the weekend.

&&

.DISCUSSION...

Westerly flow aloft transitions to southwesterly over the coming
24 hours ahead of a Pacific trough and sub-tropical jet. This
initial pattern will keep high temperatures just above normal
through Thursday.

Broad troughing and the Pacific sub-tropical jet will nudge into
the region by Friday, with a small chance of showers and
thunderstorms as early as Thursday but ramping up Friday.
Precipitable water content will quickly rise with this feature,
becoming 0.75-1 inches with surface dew points in the 50s
becoming common. This should produce a plume of adequate
instability for scattered showers and thunderstorms, mainly in
the afternoon and evening hours. The unseasonably moist
atmosphere combined with the left exit region of the jet streak
aloft will bring the potential for moderate to heavy rainfall
rates. The current WPC Excessive Rain Outlook includes a slight
risk of flash flooding mainly north of a Tucson/Willcox line
with this area through central Arizona under the more favorable
jet dynamics aloft. With strong flow aloft, an isolated strong
to potentially severe thunderstorm threat may be possible if
surface based instability develops.

Transient ridging between mid-level waves brings a mostly drier
forecast for Saturday, then a deeper trough passage looks
likely Sunday into Monday. Lingering moisture ahead of the next
system will keep a slight chance of rain in the forecast late
Saturday with chances increasing early Sunday morning. Guidance
is impressively consistent in showing well above normal 1-1.5
inch precipitable water values associated with this wave on
Sunday, 2.5-3 standard deviations above normal for this time of
year. Good divergence aloft associated with the sub- tropical
jet combined with the moisture plume will likely bring healthy
rainfall rates over a longer duration, even though convective
instability (and therefore thunderstorm potential) will likely
be less with this second wave. Areas that should see greater
rainfall totals Sunday into Monday include high terrain from
Tucson north and east, along with any areas that see an
extended period of moderate rainfall. Some locations will just
see light rain, but the higher end of the probabilistic envelope
is impressive with an exceedance of 1 to 2 inches possible,
especially in the aforementioned north- northeast of Tucson
areas and the higher terrain. This includes the Mogollon Rim
into the Gila National Forest, therefore increased flows in
creeks and rivers across northern Graham and Greenlee may be a
concern, including the San Francisco, Blue, and Gila rivers. The
NBM shows a 40-70 percent chance of at least an inch Sunday
into Monday in these favored areas with 10-30 percent chances of
at least 2 inches of rain.

Temperatures across southeastern Arizona will fall with this
weather maker duo, likely becoming coolest Sunday and
potentially Monday. Currently forecast highs for Sunday are 7 to
near 15 degrees below normal and areas that see extensive cloud
cover and rain through the day will likely be on the colder end
of this spectrum.

Though the main upper level wave will likely have exited to the
east by Monday, lingering moisture and cyclonic flow aloft will
keep a chance of showers in the forecast.

&&

.AVIATION...Valid through 28/12Z.

SKC with surface wind light and terrain driven 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 isolated
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 slightly above normal through Thursday, then lower back
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 and Monday. Minimum RH values
will be in the 15-25 percent range Tuesday 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.

&&

$$

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

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