865
FXUS65 KTWC 172053
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
153 PM MST Mon Nov 17 2025

.SYNOPSIS...Another storm system moving into Southeast Arizona the
middle of the this week will bring cooler temperatures, chances
for precipitation including snowfall above 7000 feet in the Sky
Islands, and breezy conditions on Tuesday. High temperatures will
run 2 to 6 degrees below normal through Tuesday, then fall 10 to
13 degrees below normal by the middle of the work week. The first
widespread freeze is expected Friday for the valleys to the south
and east of Tucson.

&&

.DISCUSSION...As the upper level low continues to eject out of the
region, now in southeastern Wyoming/ western Nebraska, a cut-off
low now over the Bay Area in central California is pulling
moisture into southern Arizona influencing the clouds we see
today. This cut-off low will continue to dig southward over the
next 24 hours eventually making it down to just off the southern
California coast where it will then nearly stall for roughly 24 to
36 hours. While the low is stalled, this is when we will see the
impacts associated. A push of subtropical moisture from the Gulf
of California will make it`s way into southwest and central
Arizona starting this afternoon and will continue through
Wednesday.

Given that the cut-off low will stall over southern California,
favorable lift and dynamics aloft over western and central Arizona
will influence 48 hour probabilities for up to 0.5 inch to 25% to
50% from Tucson north and west. We will start to see
precipitation spread out across the majority of the area Wednesday
and Wednesday night as the upper low begins to push inland.
Across southeastern Arizona, rainfall totals through Thursday
range between 0.25 to 0.75 inches with some areas in far western
Pima county seeing possibly up to 1 inch.

Snow is possible in the Sky Islands and the White Mountains with
this system, heavier snow totals expected in the Whites. Snow
levels in the Catalina`s will start out Wednesday morning between
8000-8500 ft, lowering to 7500-8000 ft by Wednesday night.
Overnight Wednesday snow levels drop to 6500 ft staying at this
level through Friday afternoon. Snowfall totals in the Catalina`s
range from 1-2 inches between 7500 to 8000 ft elevation and up to
5 inches at the peak. In the Whites, snow levels will start out
around 9000 ft Wednesday morning lowering to 8500 ft by Wednesday
night. Overnight Wednesday, snow level drops to 7500-8000 ft by
the Thursday morning continuing to lower to 7000 ft by the
afternoon staying at this level through Friday afternoon.
Snowfall totals in the Whites range from 9 to 12 inches. In the
Pinelano`s snowfall totals range from 4 to 6 inches.

Another impact associated with this cut-off low is cooler
temperatures well below normal. Wednesday high temperatures are
forecast to be in the mid to low 60s in the valleys and in the 30s
on the mountains. Thursday high temperatures are forecast to be
in the high 50s to low 60s in the valleys and in the high 20s to
low 30s on the mountains. Low temperatures Friday will likely
lead to the first widespread freeze of the season extending from
the Gila River Valley down to Nogales.

&&

.AVIATION...Valid through 19/00Z.
From KTUS westward, clouds are BKN to OVC AOA 6-10k ft AGL and
FEW to SCT AOA 20-25k ft AGL. KTUS eastward clouds are FEW to SCT
AOA 6-10k ft and FEW AOA 20-25k ft AGL. Clouds will continue to
increase throughout the afternoon becoming BKN to OVC AOA 6-10k ft
and 20-25k ft AGL across the whole are by 18/10Z. High clouds will
begin to push out of the area by 18/16Z leaving BKN to OVC clouds
AOA 6-10k ft AGL. This trend will continue through the rest of the
forecast period. SFC winds will be northwest from KTUS to KSAD
shifting to the south by 18/05Z. Southwest of KTUS and KSAD winds
are from the southwest and will shift to the south by 18/07Z.
Winds be generally less than 12 kts gradually increasing to 12 to
20 kts by 18/20Z, still from the south, gusting to 25-30 kts. SFC
winds will continue through the rest of the forecast period.
Precipitation chances begin to increase around 18/22Z to 20-50%
from KTUS north and westward with only 0.01 to 0.05 inches
forecast through this forecast period. Aviation discussion not
updated for TAF amendments.

&&

.FIRE WEATHER...Another storm system will impact Southeast Arizona
late Tuesday across central and western Pima county, then the
rest of Southeast Arizona Wednesday into Thursday morning. This
feature will bring another round of precipitation including snow
above 7000 feet, well below normal temperatures and breezy south
to southwest winds (Tuesday). RH values will be well above
critical levels, with Min RH values 30-40 percent in the valleys
and 60-70+ percent in the mountains.

&&

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

$$

Malarkey

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