Cascabel, Arizona Weather Forecast Discussion

136
FXUS65 KTWC 222139
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
239 PM MST Mon Sep 22 2025
.SYNOPSIS...Ample moisture across the region will result in
isolated to scattered showers and thunderstorms each day through
the middle of next week, with stronger storms, potentially with
heavy rainfall, impacting Southeast Arizona late in the week.
Temperatures will be running 3-6 degrees above normal through
Wednesday.
&&
.DISCUSSION...Happy astronomical Fall! Clouds are forming across
the area starting along the terrain with isolated storms and
showers developing. With ample moisture still in place, 18Z upper
air sounding launched at Tucson shows 1.56 inches, and the trough
off the coast of California is influencing just enough lift for
there to be a 20% chance for storms and showers this afternoon
into the early evening. Activity will be focused to the south and
east of Tucson closer to the International Border. The main
concern with storms and showers is locally, brief moderate to
heavy rainfall that may lead to minor flooding. A secondary
concern is gusty outflow winds. Temperatures today will be a few
degrees cooler today than yesterday with highs in the mid 90s in
the lower elevations and in the mid 70s in the higher elevations.
Heat Risk will be Minor today with locally Moderate areas Tucson
westward.
The upper pattern continues to be defined by high amplitude
trough of low pressure extending SW off the California Bight and a
subtropical high centered over the Chihuahua Mexico. This trough
will oscillate to the west over the next few days pulling a
short ridge high into our area. This will limit storm coverage
and increase temperatures. The short- lived increasing
temperature trend will peak on Wednesday which will push areas
Tucson westward into Moderate HeatRisk with locally Major
HeatRisk. High temperatures will be around 100 degrees in the
lower elevations.
The GEFS and ECMWF ensemble members are consistent with the
evolution of the upper- low near the California Bight moving north
into central CA Wednesday...then slowly ESE into the western
portions of Arizona by the end of the week. The combination of
strong divergence/deformation in the mid- upper levels over SE AZ
on Thursday and especially Friday, moderate 0-6km shear, and the
potential for strong advection of dry-air entraining into the
middle and upper-levels of storms (increasing the potential for
strong to severe downdraft/outflows due to enhanced evaporation)
will increase the potential for more widespread severe weather
across our neck of the woods. In addition to the aforementioned
mechanisms, decent moisture will remain in place for heavy
rainfall across Southeast Arizona as well. The latest NBM run has
a 15-30% chance of 24-hour rainfall exceeding an inch across the
SE half of our forecast area as early as Thursday, Friday and
extending into Saturday. We continue to be in the slight risk
category by WPC (at least 15 percent chance of rainfall exceeding
flash flood guidance within 25 miles of a given point) for both
Thursday and Friday.
There is still some variability in the direction the low will
move now and especially into the weekend. A lot can still change
with the intensity/ track/ timing of the upper-low so there is
caution in jumping-on this solution with both feet this early.
However, it is still prudent to start the discussion on its
potential.
&&
.AVIATION...Valid through 24/00Z.
FEW to SCT clouds AOA 5-10k ft AGL are developing across the area
through 23/00Z becoming SCT to BKN AOA 12-15k ft AGL until
23/04Z. Aft 23/04Z clouds will gradually dissipate to SKC by
23/07Z. Isolated to scattered -TSRA this afternoon into the early
evening especially to the E and SE of Tucson. Gusty and erratic
winds to around 35 kts will accompany thunderstorms. Outside of
thunderstorms, SFC winds will be 5 to 10 kts from the northwest in
the afternoon becoming light and variable overnight. Aviation
discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Above normal amount moisture across the region
will result in isolated to scattered showers and thunderstorms
each day through the middle of next week. Stronger storms are
expected late in the week. Minimum RH values between 20-40
percent today, lowering to 20-30 percent by the middle of the
week. 20-foot winds will be westerly 8-12 mph with some
afternoon/early evening gusts to around 20 mph. Breezy southwest
winds 10 to 20 mph will be possible Thursday and Friday.
Temperatures will be running 3-6 degrees above normal through
Wednesday and returning to near normal by the end of the week.
&&
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Malarkey
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NWS TWC Office Area Forecast Discussion