Mescal, Arizona Weather Forecast Discussion

863
FXUS65 KTWC 242143
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
243 PM MST Wed Sep 24 2025
.SYNOPSIS...Above normal moisture across the region will result
in isolated rain showers and thunderstorms today. Temperatures
will be running above normal today and tomorrow, resulting in
Moderate Heat Risk. A weather system will bring stronger storms
starting Thursday with impacts gusty winds and risks for flash
flooding. A Flash Flood Watch is in effect from Thursday morning
for areas Tucson eastward lasting through Saturday evening.
&&
.KEY MESSAGES...
Today: Isolated thunderstorms and rain showers for areas south
and southeast of Tucson. Temperatures will be running 3-6 degrees
above seasonal normal. Moderate HeatRisk.
Thursday-Weekend: A weather system will bring strong
thunderstorms and wetting rain showers.
- A Flash Flood Watch is in effect from Thursday morning through
  Saturday evening.
- Expect strong gusty and erratic winds from thunderstorms more so
  Tucson westward. Blowing dust is possible Thursday afternoon
  especially areas west of Tucson.
&&
.DISCUSSION...Mostly sunny skies with clouds building along the
terrain across Southeast Arizona with some showers and
thunderstorms. Similar to yesterday, there is ample moisture in
the area but we will be relying on surface heating and the
terrain for storm development. High temperatures will be in the
low 100s through tomorrow with Moderate HeatRisk Tucson westward
and Minor HeatRisk east of Tucson. Normally, our last 100 degree
day in Tucson should be today, but we will likely to see our last
100 degree day tomorrow before the big story for the region.
The low pressure system that will move into the region starting tomorrow
is currently off the coast of south-central California. The low
will bring well above normal moisture leading to high chances for
rain and thunderstorms across the area. This enhances the concern
for flash flooding, rises in washes that may overflow and
significant rises in rivers. Coordinating with the Colorado River
Basin Forecast Center, the concern for rivers to go into action
stage or overflow banks is very low. Once the low moves into our
region it will further tap into moisture from Mexico and provide
significant instability leading to the development of strong
thunderstorms which will further boost the potential for heavy
rainfall. The HREF shows a 30-70% chance for greater than 1 inch
of rainfall Tucson eastward through Thursday. The NBM has
widespread chances of around 50-70% for greater than 1 inch of
rain Thursday through Saturday focused Tucson eastward. Several
medium range models show greater than 2 inches and upwards of 3
inches of rainfall possible along the terrain.
The secondary concern with this low pressure system is the
potential for strong thunderstorms that will be capable of
producing strong gusty winds, hail, and blowing dust-
particularly areas west of Tucson. The HREF shows a 50-90% chance
for greater than 30kt winds Thursday and the NBM has a 50-90%
chance chance for greater than 30kt winds Friday. Over the three
day period, Friday looks to be the day with most significant
chances for severe weather, for both flash flooding and strong
winds. The Flash Flood Watch has been expanded to include Pinal
county starting Friday morning. Otherwise the Flash Flood Watch is
for areas Tucson eastward beginning tomorrow morning through
Saturday evening. Rain showers will persist through the overnight
hours, priming for a more active weather pattern for the weekend.
The low pressure center will stall a bit over the region with some
minor tweaks of its position. This will continue to bring heavy
rainfall potential across most of Southeast Arizona into the
weekend. Expect strong afternoon thunderstorms and overnight rain
showers with embedded thunderstorms. Expect rivers, creeks,
washes, and anything that drain to flow quickly and lasting
through most of the weekend. There will be lulls between rain
showers and thunderstorms but that will help recharge for more
active, and strong, storms in the afternoon. The weather system
will push out by the end of the weekend.
A very active end to the monsoon.
&&
.AVIATION...Valid through 26/00Z.
SKC to FEW clouds AOA 10-12k ft AGl mainly sticking to the higher
terrain. Clouds will dissipate by 25/03Z becoming SKC until
25/17Z. Aft 25/17Z clouds will increase to SCT to BKN mainly KTUS
eastward AOA 5-10k ft AGL. Now through 25/17Z very isolated
showers and storms possible mainly KTUS south and east. After
25/17Z, scattered to widespread showers and thunderstorms likely
KTUS eastward through the rest of the forecast period. SFC winds
will be from the northeast generally less than 12 kts this
afternoon becoming light and variable overnight. Tomorrow
afternoon starting around 25/18Z winds will be from the southwest
at around 5 to 10 kts. Gusty and erratic winds to around 35 kts
will accompany thunderstorms tomorrow afternoon. Aviation
discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Above normal monsoonal moisture will linger
through today, providing isolated thunderstorms and rain showers
south and east of Tucson. Min relative humidities will be
bottoming out at 20-30 percent today through Thursday. By
Thursday, a weather system will bring higher chances for wetting
rain showers and stronger thunderstorms through the start of the
weekend. Outside of thunderstorm winds, general winds will be less
than 15 mph with the occasional gust up to 20 mph today. The Gila
Valley will have southeasterly breezes early Thursday morning.
Expect southerly to southwesterly breezes late Thursday through
Friday due to the incoming weather system. Daytime temperatures
will be running 3-6 degrees above normal through at least Thursday
and dropping to near normal by the weekend.
&&
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Flood Watch from Thursday morning through Saturday evening for
AZZ503-504-506>514.
Flood Watch from Friday morning through Saturday evening for
AZZ505.
&&
$$
Malarkey
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NWS TWC Office Area Forecast Discussion