Sierra Vista, Arizona 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

648
FXUS65 KTWC 032149
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
249 PM MST Tue Dec 3 2024

.SYNOPSIS...

Near to above normal temperatures through the weekend. Slight
chances for light rain and high elevation snow arrive east of
Tucson during the second half of the work week. Cooler
temperatures are possible early next week.

&&

.DISCUSSION...

The upper level pattern remains defined by an amplified ridge
centered over the west coast with a weak trough underneath. This
trough and an associated jet streak were beginning to cross the
southwest coastline this afternoon. Under modest upper level
divergence associated with the approaching jet streak, a tightened
surface pressure gradient has produced breezy southeast winds
earlier today, which will turn southwest as the upper jet crosses
through this evening. Observed wind gusts have ranged from 15 to
25 mph across much of southeastern Arizona today and while
breezes will continue through the early evening, these gusts
should gradually diminish in magnitude over the next few hours.

The upper low will stall and become at least partially cutoff over
the desert southwest over the next several days. This will bring
temperatures down closer to normal, though still likely a few
degrees above with a lack of a more significant cold push
associated. Additionally, recent model trends bring in a bit more
moisture into eastern portions of the area as the low wraps up.
The depth of this moisture remains uncertain however as there are
model differences in the strength of of the upper low and how far
west its able to bring in moisture adequate for precipitation. At
this point chances for light showers and high elevation snow are
highest in the White Mountain area and near/east of Safford-
Willcox-Douglas, with probabilities Thursday and Friday ranging
from 20 to 30 percent and near 40 percent in the Whites (with
slight chances there starting as early as tomorrow afternoon).
Overall precipitation amounts should be light with no more than a
few hundredths likely at any one location with just light snow at
the mountain tops.

An upper level pattern switch still looks reasonably likely early
next week with a digging trough dropping south/southeast out of
the Pacific northwest. At this lead time there remains notable
differences in the wave amplitude (partially dictated by how soon
the previous cutoff low exits), which will impact temperature
probabilities. Ensembles generally agree on the occurrence of the
pattern switch overall, with the warmer side of the ensemble
spread still bringing highs down to normal levels (instead of the
above normal temperatures southeastern Arizona has been seeing). A
deeper solution would bring colder temperatures and potentially
precipitation chances, however a more dry outcome with cooler
temperatures looks more likely given the trajectory.

&&

.AVIATION...Valid through 05/00Z.

Southeasterly winds in the Upper Gila River Valley and southerly
to southwesterly winds elsewhere will drop to 7 to 10 kts this
evening, before becoming light and terrain driven after 04/03Z.
Winds will then be light through Wednesday. Generally SKC through
the period with a few cirrus clouds. Some low stratus can`t be
ruled out early Wednesday morning in eastern areas such as near
KSAD- KDUG, however confidence is low in this outcome. Aviation discussion
not updated for TAF amendments.

&&

.FIRE WEATHER...

Near normal to above normal temperatures continue
through the week. Minimum relative humidities will be on the
gradual increase over the next several days. Values tomorrow
range from 15 to 20 percent west of Tucson and south near the
International Border, to 30 to near 40 percent in the Upper Gila
River Valley. By Friday lowest values should exceed 25 percent
across most of southeastern Arizona with minimum relative
humidities above 35 percent east of Tucson. This moisture push
will also bring slight chances for light showers and high
elevation snow during the second half of the week, generally in
eastern zones. Winds Wednesday through the weekend will be light
and terrain driven.

&&

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

$$

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