523
FXUS65 KTWC 010844
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
144 AM MST Sun Nov 1 2026

.SYNOPSIS...Widespread rain for much of the day today into
this evening with a few embedded thunderstorms as a weather system
moves through. Some lingering shower activity will persist into
Monday morning, then drier air moves in for the remainder of the
work week. A Flood Watch is in effect for all of southeast Arizona
through 5 AM Monday.

&&

.DISCUSSION...The atmospheric river (AR) event continues this
morning across southeast Arizona, aided by a strong subtropical jet
just ahead of a strong upper level trough. Rainfall amounts so far
have overperformed a bit for much of the region with most locales
seeing 0.25" to 1 inch of rain in the last 24 hours. Lesser amounts
have occurred in Cochise County and higher amounts of 2 to 3 inches
have been observed on Mt. Lemmon and Mt. Graham. Latest KEMX radar
imagery shows most locales remaining dry southeast of Tucson with a
solid area of light to moderate rain with localized pockets of heavy
rain from approximately the Tucson area and points north/west. This
precipitation orientation will continue through about mid morning
with the CAMs in good agreement on the precipitation shield mainly
staying from the Tucson area north and westward through about 9 AM.
As the day progresses, a band of moderate rain with pockets of heavy
rain with embedded thunderstorms will shift from west to east across
the region, exiting eastern areas this evening. This band will
produce rainfall rates around 0.25" to 0.50" per hour (locally
higher in any thunderstorms) as it moves through in a 4 to 6 hour
period. For some context, the atmosphere is at record levels of
moisture (1.2" to 1.6" PWAT or 5 to 6 standard deviations above
normal) for this time of year. Thus, the combination of the dynamics
with the subtropical jet max along with moisture levels more
typically seen in summer will continue to result in efficient
rainfall. While the bulk of the precipitation will occur through the
day and into the evening, some localized pockets of moderate rain may
still occur tonight into Monday morning. This will be along a
trailing secondary band of precipitation aided by the upper level
trough across the northern half of Arizona with this band slowly
push south and east, focused on areas north and west of Tucson
tonight.

While there will be potential for some embedded thunderstorms today,
limited instability will be a significant mitigating factor. SPC has
outlined much of our forecast area in a marginal risk (level 1 of 5)
for severe thunderstorms with wind being the main threat as stronger
winds aloft can translate down to the surface in any stronger
thunderstorms. Even outside of thunderstorm activity, breezy
southwest winds are expected today.

Additional most likely rain amounts from 5 AM this morning to 5 AM
Monday continue to range from about 0.3" to 1.2" in valleys with
localized amounts of 2 to 3 inches mainly in valleys north of Tucson
and in the mountains from Tucson northeastward. This additional
precipitation will continue to result in responses in area rivers,
creeks, and washes across SE AZ. See hydrology section below for
further details.

Here is a look at updated additional rainfall ranges from 5 AM
Sunday to 5 AM Monday.

-Expected: Valleys 0.30"-1.2", Mountains 1"-3"

-Low end (9 in 10 chance):
 Valleys 0.10"-1.0", Mountains 0.75"-2"

-High end (1 in 10 chance):
 Valleys 1.2"-2.5", Mountains 3"-4" locally higher

Lingering showers will diminish Monday morning with no significant
rainfall expected. Thereafter, dry conditions as shortwave ridging
builds in. This shortwave ridging will traverse across the regions
Tuesday with dry conditions still continuing beyond Wednesday and
Thursday as westerly flow prevails. Some semblance of troughing
around Friday but still some differences in the ensembles and
moisture is lacking so will keep PoPs below mentionable levels into
next weekend. Temperatures will be 4 to 7 degrees below normal for
most of this week.

&&

.AVIATION...Valid through 02/12Z.
Expect periods of MVFR cigs at all terminals through 02/02Z with
brief IFR cigs possible especially at KDUG and KOLS. Numerous SHRA
with slight chc -TSRA mainly from KTUS/KOLS westward through about
01/16Z, then that shifts eastward thereafter before exiting eastern
areas around 02/03Z. Additional SCT -SHRA possible mainly north and
west of KTUS tonight through end of valid period. Vis down to 1-2
miles will be possible in SHRA or TSRA today. SFC winds mainly
SELY/SLY 5-10 kts this morning becoming SWLY 12-20 kts and gusts 25-
30 kts after 01/18Z, then gradually diminishing aft 02/06Z. Near
stronger TSRA wind gusts of 30-40 kts will be possible. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Widespread showers and isolated thunderstorms today
into tonight, with some areas of heavy rain. The heaviest rain will
be over the higher terrain. Some lingering shower activity will
persist into Monday morning with dry conditions thereafter.
Afternoon high temperatures will lower below normal through the
forecast period. Breezy to locally windy southwest winds expected
today, turning northwest Monday. Minimum RH levels values into early
next week will be 40+ percent.

&&

.HYDROLOGY...Precipitation on Saturday ranged from 0.25" to 1 inch
in the valleys with up to 2 to 3 inches in some mountains and that
is setting the stage for more significant flooding concerns today
through tonight. We`re already seeing some increased flow in quicker
responding washes such as Sabino Creek and more urbanized washes in
the Tucson Metro (such as Alamo Wash) with the rain that moved
through last night. As another round of moderate to heavy rain moves
through today into this evening, that will continue to further
exacerbate flooding concerns with a more rapid and potentially more
impactful response in the area rivers, creeks and washes. There is
the potential for significant rises on the San Francisco River, Blue
River, Gila River, Eagle Creek, and Sabino Creek with anywhere from
Minor to Major flood stages possible.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Flood Watch through late tonight for AZZ501>515.

&&

$$

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