Forecast Discussion

Forecast Discussion for TWC NWS Office
130
FXUS65 KTWC 272038
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
138 PM MST Mon Jan 27 2025

.SYNOPSIS...Seasonable temperatures today then below normal
temperatures Tuesday through Thursday. A storm system will approach
and move through the area through much of this week bringing
breezy conditions today, and chances for valley rain and mountain
snow with the best precipitation chances Wednesday. Temperatures
then rebound to above normal this weekend.

&&

.DISCUSSION...Water vapor shows an upper level low centered just
south of Las Vegas. This is leading to scattered showers over
north central Arizona and a cumulus field from Tucson westward and
north. A light shower or two will be possible this afternoon and
evening in western Pima County, but overall chances are low (15
percent) to see any measurable precip. Otherwise clouds will stick
around over the western half of the CWA with high temperatures a
few degrees below normal. Winds will also be breezy south and east
of Tucson. The winds and dry conditions will lead to elevated
fire weather conditions along the AZ/NM border.

The upper level low will slowly move across Arizona over the next
couple of days. Moisture ahead of the system will be fairly
shallow and PWAT values will be right around normal to just above
normal for this time of year. Tuesday, thanks to the orientation
of the trough and area of synoptic scale lift the best precip
chances will be to the north. HREF members do show a few very
isolated showers across southeast Arizona, but little measurable
rain is expected. Best chances will be from Tucson west and north.
Wednesday rain chances become more widespread as the core of the
trough passes just to the north of the area. Hi-res guidance,
even though its at the tail end of their forecast, shows isolated
to scattered shower activity. QPF will be on the lighter side,
generally less than 0.15" with isolated higher amounts possible in
Pinal, Graham, and Greenlee counties. Snow amounts in the
mountains expected to be 1"-4" with mountains north of I-10 on the
higher end of that range and those south of I-10 on the lower
end. Snow levels drop to 3500-4000 feet Wednesday morning, so
some flurries are possible for valley floors east of Tucson but no
accumulation is expected. Lingering snow showers will be possible
Thursday in the White Mountains. Temperatures will drop to 9-13
degrees below normal Tuesday into Thursday with Tucson possibly
seeing another freeze Thursday morning. However cloud cover could
keep overnight temperatures above freezing.

By Thursday the low will be moving into the southern Great Plains
and ridging will be building in behind it. With heights increasing
temperatures will also be on the increase. Friday expect highs to
be around normal then increasing to above normal by this weekend.
Tucson could see high temperatures in the low 80s again by early
next week.

&&

.AVIATION...Valid through 29/00Z.
From Tucson-Nogales west, expect BKN clouds 4-8kft AGL for the
entire period. East of Tucson skies will be SKC through tonight
then FEW-SCT cumulus 4k-8k developing Tuesday afternoon.
Slight chance (20 percent) of -SHRA Tuesday afternoon mainly from
Tucson northward. SFC winds SWLY winds 10-18 kts with gusts 25-30
kts through the early evening then becoming variable less than 8
kts. Strongest winds will be at KDUG terminal. Tuesday afternoon
winds become southwesterly 10-15 kts with KDUG again on the
higher end of that range. Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Elevated fire weather conditions are expected
mainly across Cochise County this afternoon, but not widespread
enough for Red Flag issuance. As a weather system moves through
this week it will bring a chance for mountain rain and valley snow
with the most widespread precipitation chances on Wednesday. Min
RH values will be 15-30 percent in the valleys and 30-45 percent
in the mountains through Friday. This weekend min RH drops to
below 15 percent.

&&

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

$$

Hardin

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NWS TWC Office Area Forecast Discussion