101
FXUS65 KTWC 040746
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
1246 AM MST Thu Dec 4 2025

.SYNOPSIS...Cooler temperatures in the wake of an departing weather
system that brought light showers to Southeast Arizona Wednesday
will result in below normal temperatures across the region through
Saturday. Cold morning low temperatures are expected the next few
mornings, with widespread sub-freezing temperatures expected in
the valleys east and south of Tucson. Otherwise, a ridge of high
pressure begins to establish itself into the Desert Southwest
Sunday into next week. This will result in afternoon high
temperatures warming to above seasonable levels late this weekend
into the middle of next week.

&&

.DISCUSSION...The upper pattern this morning is primarily defined
by an upper trough of low pressure moving east through northern
New Mexico, a trough axis extending from this feature to the SW
across far Southeast Arizona, and a positively tilted ridge of
high pressure centered near 35N/139W. We continue to see the
frontal boundary wash-out as it slowly drags through Cochise
county early this morning...with the majority of the light showers
observed via KEMX having since tapered off over the past few
hours.

The positive tilt of the upper ridge in place across the Eastern
Pacific will keep the mean trough situated across the Desert
Southwest the next few days despite the departure of the main
upper low that brought us the light showers yesterday afternoon/
evening. This will reinforce a cool airmass over our neck of the
woods with afternoon high temperatures around 5 degrees below
seasonable normals both today and Friday. With reduced cloud
cover and surface dewpoints falling from the upper 30s to near 40
in the valleys of Southeast Arizona this morning, to the lower 30s
Friday morning and mid 20s Saturday morning...we will start to see
widespread sub-freezing temperatures take root in the valleys to
the east and south of Tucson Friday and Saturday morning. These
freezing temperatures will be the first freeze of the season for
some of these locations. Therefore, there is a Freeze Warning in
effect from 2 am to 9 am MST Friday to highlight the impact of the
first freeze.

Otherwise, temperatures will begin to rebound and become more
mild as we move from Sunday into the middle of next week as the
upper ridge amplifies and becomes more of a dominant feature to
our west.

&&

.AVIATION...Valid through 05/12Z. SKC west of KTUS and SCT-BKN
5k-8k ft AGL east of KTUS thru 04/17Z clearing from west to east.
FEW-SCT 8k-11k ft AGL and SCT-BKN clouds AOA 20k ft AGL mainly
from KTUS eastward aft 04/17Z. SFC wind will be variable less
than 12 kts thru 04/17Z, then WLY/NWLY around 12 kts this
afternoon. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...A cool airmass in the wake of an departing weather
system that brought light showers/wetting rains to Southeast
Arizona Wednesday will result in below normal temperatures across
the region through Saturday. Cold morning low temperatures are
expected the next few mornings, with widespread sub-freezing
temperatures expected in the valleys east and south of Tucson.
20-foot winds will generally be WLY/NWLY around 10 mph in the
afternoon with light terrain driven winds less around 5 mph
overnight. Min RH values will be in the 25-35 percent range
through Friday, lowering to 20-30 percent this weekend into the
middle of next week. Dry weather returns Thursday and persists
into the middle of next week. High temperatures will be below
normal through Saturday, warming a couple of degrees above normal
on Sunday and then 5-8 degrees above normal next week.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Freeze Warning from 2 AM to 9 AM MST Friday for AZZ503-507>509.

&&

$$

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