Mescal, Arizona Weather Forecast Discussion

430
FXUS65 KTWC 071638
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
938 AM MST Sun Sep 7 2025
.SYNOPSIS...Drying trend commences today with only slight chances of
precipitation, then mainly dry Monday and Tuesday. Some moisture mid
to late week will result in slight chances for showers and
thunderstorms mid to late week, especially east of Tucson. Most of
the week will have near normal temperatures.
&&
.KEY MESSAGES...
- A drying trend leading to only slight chances (15-20%) of
  isolated showers and thunderstorms mainly along the higher
  terrain over the next few days.
- Better moisture and forcing mid to late week will allow for some
  increased shower and thunderstorm chances (20-40%)
- Temperatures remain near normal throughout the week.
&&
.UPDATE...
Latest hires models still indicating isolated showers and
thunderstorms are mainly possible along the higher terrain today
mainly south of Tucson, with little overall forcing available.
Storm motion today will be slow with only about 5 knots from the
northwest. Mesoanalysis indicates PWATs of a little less than an
inch to 1.25" across much of the region, decent low-level lapse
rates of 7-9 C/km, and DCAPE of 1100-1500 J/kg. All of that to
say, any `strong` showers/thunderstorms that do develop today may
result in minor flooding issues due to slow moving, heavy
rainers. Also, brief gusty winds to around 30-45 mph will also be
possible with the strongest storms. As a result, not anticipating
any severe thunderstorms today, but could see some localized
minor flooding issues. Best chances for seeing the `strongest`
storms will mainly be in Santa Cruz County today.
&&
.PREV DISCUSSION... /issued 230 AM MST Sun Sep 7 2025/
.DISCUSSION...Mostly clear skies this morning across southeast
Arizona. Ridging aloft is building in today which combined with a
gradual drying process will result in less convective activity
today. Still enough moisture and instability to support slight
chances for showers and thunderstorms, especially across the higher
terrain and to the south of Tucson in Santa Cruz County. Any storms
that do manage to develop will be slow moving and capable of
producing locally heavy downpours. With that said, the bulk of us
will remain dry today with high temperatures warming back up to
seasonable levels.
A fairly typical September transition pattern this week with the
monsoon waning as the subtropical high sinks to our south with west
to southwesterly aloft prevailing. PWAT`s continue to lower to
around 0.8 (east) to 1.2 inches (west) Monday and Tuesday. This will
be just enough for a slight chance (~10 percent) of showers and
thunderstorms across the higher terrain with PoPs below mentionable
levels for valleys. By Wednesday and Thursday as a longwave trough
moves inland into California and the Great Basin, the flow will
become slightly more southerly and this will advect a bit more
moisture northward especially from Tucson eastward, supporting
slight chances for showers and thunderstorms for most locales. Drier
air will then try to nudge back in Friday through next weekend with
most locales staying dry. Temperatures this week will be near
normal.
&&
.AVIATION...Valid through 08/12Z.
SKC-SCT 6k-10k ft AGL this morning, then aft 07/19Z locally BKN
clouds mainly over the mtns and south of KTUS including KOLS.
Gradual clearing aft 07/03Z thru the end of the valid period. ISOLD
-SHRA/-TSRA focused on the higher terrain and could impact KOLS but
confidence/chances too low to include in TAFs. Expect wind gusts up
to 40 kts with the strongest storms. Surface winds less than 12 kts
thru the forecast period, trending WLY/NWLY between 08/18Z and
09/03Z and variable otherwise. Aviation discussion not updated for
TAF amendments.
&&
.FIRE WEATHER...Minimum relative humidities 25 to 40 percent
today, lowering to 15 to 30 percent much of next week. Drier air
today with just enough moisture for a slight chance of showers and
thunderstorms. Most locales stay dry Monday and Tuesday with slight
chances of showers and thunderstorms mainly over the higher terrain.
Thereafter, some moisture returns for a slight chance of showers and
thunderstorms mainly east of Tucson mid to late week before drying
resumes again next weekend. Surface winds mainly light through the
forecast period, except gusty and erratic in or near any
thunderstorms. High temperatures near normal for most of this week.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
Update...Peters
Discussion...Lader
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NWS TWC Office Area Forecast Discussion