727
FXUS65 KTWC 182030
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
130 PM MST Fri Apr 18 2025

.SYNOPSIS...A weather system will move across northern Arizona
tonight into early Saturday before shifting east of the region.
This system will result in breezy conditions into the evening hours
tonight mainly east of Tucson, along with below normal temperatures
through Sunday morning. There will also be a chance of light valley
rain and mountain snow tonight into Saturday. Temperatures rebound
to above normal levels next week.

&&

.DISCUSSION...An upper low in the northern Great Basin will move
south to along the Arizona/Utah border this evening, across northern
Arizona tonight and then into New Mexico on Saturday. This system
then shifts eastward into the Great Plains Sunday as high pressure
aloft begins to build back in across the desert southwest. High
pressure aloft will then prevail across the area through next week.

Lowering heights today and Saturday will result in cooler
temperatures across southeast Arizona, with highs in the 70s today
and in the mid 60s to lower 70s Saturday in valley locations.
These readings are 7-10 degrees below normal. Near freezing morning
lows will occur Sunday morning in the colder eastern valley
locations such as the Sulphur Springs Valley, where a few areas
could dip to freezing for an hour or two. Breezy conditions continue
today to the east of Tucson, with isolated near critical to critical
fire weather conditions into the early evening hours tonight east of
a Sierra Vista to Safford line. Wind gusts have generally been
between 25 and 35 mph, with the Guthrie and Headquarters RAWS sites
topping out at 41 mph. However, minimum RH values at most locations
have stayed above critical thresholds.

This system will also bring a chance of showers mainly north and
east of Tucson tonight through mid-day Saturday, with clearing
skies from west to east Saturday afternoon/evening. Precipitation
amounts are expected to be light with around a quarter of an inch in
the White Mountains, one to two tenths on Mount Graham and Mount
Lemmon and a couple of hundredths up to a tenth of an inch in
eastern valley locations. 2-3 inches of snowfall will be possible in
the White Mountains and on Mount Graham, with 1-2 inches of snow on
Mount Lemmon.

As the system pushes east of the region on Sunday, heights begin to
rise and high temperatures warm back to near normal. High pressure
aloft then builds in across the area next week, with highs warming
to 6-8 degrees above normal. Mid to late next week, the gradient
tightens up in response to a couple of systems moving to our north,
which will result in elevated wind speeds during the afternoon/early
evening hours mainly east of Tucson.

&&

.AVIATION...Valid through 20/00Z.
FEW-SCT clouds at 5k-8k ft AGL thru 19/01Z, becoming SCT-BKN clouds
at 5k-8k ft AGL between 19/01Z and 19/14Z. Aft 19/14Z thru the
remainder of the forecast period, clearing skies from west to east
across the forecast area. Chance of valley -SHRA/mountain -SHSN
between 19/01Z and 19/20Z, primarily north and east of KTUS. SWLY
SFC wind at 15-22 kts and gusts to 25-32 kts thru 19/02Z, with the
strongest SFC wind east of KTUS in the vicinity of KALK, KDUG and
KSAD. Diminishing SFC wind aft 19/02Z and SFC wind generally 12 kts
or less between 19/04Z and 19/17Z. WLY/NWLY SFC wind aft 19/17Z,
with wind speeds of 10-18 kts and gusts to 18-28 kts thru the end of
the forecast period (with the strongest wind speeds in the vicinity
of KALK, KDUG and KSAD). Aviation discussion not updated for TAF
amendments.

&&

.FIRE WEATHER...Isolated near critical to critical fire weather
conditions will continue into the early evening hours tonight east
of a Sierra Vista to Safford line. Winds gusts have exceeded
critical thresholds in a few locations this afternoon, although min
RH values have generally stayed above critical values. Cooler
temperatures through Sunday morning, with high temperatures today
and Saturday 7-10 degrees below normal. There will be a slight
chance of light precipitation across mainly the eastern half of the
forecast area tonight and Saturday, with higher precipitation
chances in the White Mountains. A warming trend then starts Sunday
and continues through next week, as high temperatures warm to near
normal on Sunday and then 6-8 degrees above normal Monday through
Thursday.

&&

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

&&

$$

Zell

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