Expires:No;;426911
FXUS65 KTWC 290909
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
209 AM MST Mon Dec 29 2025

.SYNOPSIS...A back-door cold front will bring gusty east to 
southeast winds to portions of Southeast Arizona today through 
Tuesday. In addition to the winds, this system will also bring a 
slight chance of showers along the Arizona and New Mexico 
state-line today into tonight. Another stronger weather disturbance
is then expected to move into the region and a good chance of 
light-to-moderate valley rain and high elevation snow showers New 
Years Eve into New Years Day. Temperatures will remain near normal
levels this week.

&&

.DISCUSSION...The upper pattern this morning is defined by a
positively-tilted high amplitude ridge extending across the 
Eastern Pacific into the Pacific Northwest which is helping to
carve out a mean trough extending from central California SW 
toward a cutoff-low centered near 20N/130W. In addition to these 
upper-level features, a strong surface high is tracking south 
along the southern Rockies through eastern New Mexico. 

As this surface high continues to become established to our east,
it will nudge a back-door cold front into the eastern portions of
our forecast area today and extend across the majority of 
Southeast Arizona this afternoon...persisting into Tuesday. This 
frontal boundary will primarily impact our neck of the woods with 
strong and gusty east to southeast winds 15-25 mph with gusts to 
30-40 mph. Winds are expected to increase this morning, with the 
strongest winds occuring this evening and overnight tonight. Winds
may be problematic to those of us that have loose and unsecured 
outdoor items such as holiday decorations. We have been trying to 
focus our messaging on the winds to remind people to take proper 
precautions to secure their items from getting damaged. In 
addition to the winds, we will also see a slight chance of showers
develop along the AZ/NM state-line today and tonight as moisture 
to our south moves northward and interacts with the surface 
frontal boundary. However, these showers are not expected to be 
impactful. 

Otherwise, that upper-level cutoff-low well to the west of the 
Baja Peninsula will begin to move NNE into central/southern 
California Wednesday night into Thursday. It appears that the bulk
of the moisture associated with this feature will track into 
California, but there will be ample moisture along the SE 
periphery that will advect into Southeast Arizona begining 
Wednesday afternoon and persisting into Thursday (this includes 
New Years Eve and New Years Day). Although the best lift/dynamics 
will stay with the cutoff-low as it moves into California, 
shortwaves embedded in the SWLY flow will interact with the deeper
moisture as it tracks across Southeast Arizona. The timing of the
moderate-to-locally heavy rain and high elevation mountain snow 
will be Thursday when the cutoff-low is ejecting through NW 
Arizona. There will also be a slight chance for thunderstorms 
during the day Thursday. Given the timing of this system, it may 
be impactful to those participating in outdoor festivities to ring
in the new year. We will likely see some lingering instability 
showers Thursday night...but will quickly taper off Friday as a 
shortwave ridge nudges into the region from the west. 

&&

.AVIATION...Valid through 30/12Z. 

West of KTUS: SCT-BKN clouds AOA 20k ft AGL with addl clouds 
12k-18k ft AGL dvlpg thru end of valid pd. SFC winds less than 10
kts this morning bcmg NELY/ELY 6-12 kts with gusts 20-25 kts aft 
29/14Z and contg thru end of the valid pd. 

KTUS and East: SCT-BKN clouds 6-10k ft AGL thru 29/14Z and contg 
thru end of valid pd. ISOLD -SHRA will be possible along the AZ/NM
state-line this afternoon and evening. SFC winds NLY/NELY 6-12 
kts thru 29/14Z then bcmg E-SE 10-20 kts with gusts to 25-35 kts 
and contg thru the end of the valid pd. Aviation discussion not 
updated for TAF amendments.

&&

.FIRE WEATHER...A back-door cold front will move into Greenlee, 
Graham and Cochise counties today into Tuesday, bringing with it 
gusty east to southeast winds and a slight chance of showers along
the AZ/NM state-line. 20-foot winds will be east to southeast 
15-20 mph with gusts 30-40 mph. Otherwise, another weather system 
will bring a good chance of valley rain and high elevation snow 
showers New Years Eve into New Years Day. Minimum relative 
humidity values will remain elevated through the upcoming week, 
ranging from 35-45 percent in the valleys and 50-70 percent in the
mountains. Temperatures will remain near normal levels this week.

&&

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

&&

$$

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