099
FXUS65 KTWC 282105
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
205 PM MST Wed Oct 28 2026

.SYNOPSIS...

Dry conditions are expected across Southeast Arizona through
tomorrow. 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...

Calm weather today with some high clouds streaming into the
area this afternoon due to a shift in upper level flow to be
southwesterly. This shift in the upper level flow is preceding
a deepening Pacific trough that will push into the region
starting tomorrow. This trough brings along a subtropical jet
that will carry with it anomalously high moisture leading to a
slight chance for showers and thunderstorms tomorrow afternoon.
These showers and thunderstorms will be focused to the AZ/NM
border with a periphery as far west as central Graham and
central Cochise counties. Moisture with PWAT values upwards of 1
inch will broaden into the region Friday and combined with the
location of the subtropical jet, expand the chances for showers
and thunderstorms. Friday, showers and thunderstorms will be
focused to northern Pima through Pinal, Graham, and Greenlee
counties. In these areas there is a 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.
Heavy rainfall rates, isolated strong gusty winds, and small
hail may accompany any thunderstorm Friday. Rainfall totals
across the area Friday range between 0.1 to 0.25 inches in the
valleys and 0.25 to 0.4 inches in the mountains.

The aforementioned upper level trough that will bring unsettled
weather to the area Friday will move out of the area fairly
quickly as a stronger Pacific trough moves into the area
Saturday night. Saturday during the day, lingering moisture
will remain in the area however chances for isolated showers and
thunderstorms is minimal.

Early Sunday into early Monday a more substantial Pacific
trough will impact the region with a strong associated jet
streak. Significant moisture will be transported to the region
with PWATs up to 1.5 inches possible. 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. This
moisture combined with synoptic forcing will lead to widespread
rain with isolated embedded thunderstorms across the region.
Rainfall throughout the period will be longer duration with
periods of moderate to locally heavy rainfall rates. Rainfall
totals for Sunday into Monday range from 0.5 to 1 inch in the
valleys with 1 to 2+ inches in the mountains and in portions of
Pinal, Graham, and Greenlee counties. High rainfall amounts will
be focused to the Catalinas/Rincons northeast through the White
Mountains. Flash flooding potential returns Sunday with more
substantial flows that 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.

&&

.AVIATION... Valid through 30/00Z.

Mostly SKC across the region with FEW high clouds AOA 25k ft AGL
passing by. Cloud cover will gradually increase throughout the
afternoon becoming FEW to SCT AOA 25k ft AGL by 28/23Z. FEW to
SCT clouds will persist through the forecast period. SFC winds
will be generally less than 12 kts from the west to northwest
this afternoon becoming light and variable overnight. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...

Dry conditions are expected across Southeast Arizona through
tomorrow. 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 through Thursday, then lower below normal
tomorrow 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.

&&

$$

Malarkey/Edwards

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