Sierra Vista, Arizona 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

477
FXUS65 KTWC 151924
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
1224 PM MST Fri May 15 2026

.SYNOPSIS...Sunny and warm across Southeast Arizona with
afternoon temperatures 3 to 7 degrees above normal through
Saturday. A dry weather system tracking through the Great Basin
this weekend will bring about breezy conditions Saturday, and
then windy conditions Sunday into Monday with temperatures
lowering to slightly below normal levels.

&&

.DISCUSSION...Sunny, breezy and warm is the most succinct way to
describe the forecast. In fact, that`s the one thing about our
weather across Southeast Arizona during the month of May. While
conditions are often sunny and warm, it is those same conditions
that promote stronger winds to mix down to the surface because
of the abundant daytime surface heating.

The upper pattern today impacting our forecast is defined by two
main features. The first being a weak shearing trough of low
pressure across northern New Mexico with a baggy trough axis
extending across southern Arizona into the northern Baja. Still
some stronger winds in the mid-levels holding onto the extreme
SE corner of the state this afternoon, which should result in
some afternoon breezes with gusts to 35 mph possible in Cochise
county this afternoon.

The second feature is a strong upper low positioned along the
coastline of British Columbia Canada this morning, moving SSE
into the Pacific Northwest. The overall pattern will become
amplified along the West Coast this weekend as this feature digs
farther south and the upper ridge in the Eastern Pacific responds.
Initially we will see an increase in pressure gradients aloft
Saturday with winds mixing down for a breezy day with southwest
winds 15 to 20 mph with gusts to 30 mph. Although the main
upper-low will only make it as far south as the Great Basin
by 18/00Z Sunday afternoon, Southeast Arizona will reside on
the southern periphery of this system with stronger mid-level
flow (30-40 kts between 700-500 mb) expanding across our neck
of the woods. These winds will mix down to the surface resulting
in a windy day across the area, with southwest winds generally
20-30 mph with gusts 40-45 mph across the majority of the CWA.
These winds would be strong enough to result in some patchy
blowing dust Sunday afternoon. In addition, given the dry
airmass in place with minimum relative humidity in the 7 to 15
percent range, we will experience critical fire weather
conditions as well. The latest NBM 5.0 probability for near
critical fire weather conditions (RHs<=15 pct and 10-m winds 20+
mph) remains between 30-60 percent Sunday across the majority
of Southeast Arizona, with portions of southern Cochise between
60-90 percent. Given the increasing confidence with successive
runs indicating the same thing, we have decided to issue a Red
Flag Warning for fire weather zones 151/152/153/154 from 11 am
MST Sunday morning until 11 pm MST Sunday evening.

Although the stronger winds should hold onto the areas east of
Tucson Monday, we will see a slight increase in lower-level
moisture. Dewpoints Sunday will range from the upper teens to
mid 20s eventually increasing into the lower to mid 30s Monday.
This should help push minimum RH percentages back up into the
mid to upper teens. I am a bit skeptical that areas east of
Tucson will moisten up enough Monday to not result in another
day of critical fire weather conditions, but at this juncture
given the lower confidence, we will hold off on any fire
weather product for Monday for another day or so.

&&

.AVIATION...Valid through 17/00Z. Mainly SKC through the valid
period. SFC winds light and mainly SELY/SLY at 10 kts or less
this morning, then aft 15/18Z becoming WLY/SWLY wind 8-15 kts
with occasional gusts to 20-25 kts this afternoon. SFC winds
diminish to 10 kts or less again aft 16/03Z and become SELY/SLY.
Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Less wind today for Southeast Arizona with just
a few afternoon breezes, especially across Cochise county.
Southwest winds will start to increase Saturday with 20-foot
winds 15-20 mph with gusts up to 30 mph, and then ramp up even
more Sunday into Monday to around 20-30 mph sustained and gusts
35-45 mph. The combination of these strong winds and continued
dry conditions will result in near critical fire weather
conditions Saturday and widespread critical fire weather
conditions Sunday for the majority of Southeast Arizona, then
near critical conditions again south and east of Tucson Monday.
We have issued a Red Flag Warning for fire weather zones
151/152/153/154 from 11 am MST Sunday morning until 11 pm MST
Sunday evening.

Otherwise, high temperatures will be about 3 to 7 degrees above
normal through Saturday with cooling to slightly below normal
levels Sunday and Monday. Less winds thereafter for the middle
of next week. Minimum relative humidity values into next week
will generally be in the 6-16 percent range in the valleys and
10-20 percent in the mountains.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 11 AM to 11 PM MST Sunday for AZZ151>154.

&&

$$

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