Santa Rita Foothills, Arizona Weather Forecast Discussion

487
FXUS65 KTWC 250951
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
251 AM MST Thu Sep 25 2025
.SYNOPSIS...A weather system will bring periods of rain showers
and thunderstorms today through the weekend. A Flash Flood Watch
in effect today through Saturday. Thunderstorms will be capable of
producing strong to severe gusty winds, hail, and heavy rainfall.
&&
.KEY MESSAGES...
Active Monsoonal Period Today through Saturday.
-Flash Flood Watch is in effect this late morning through Saturday
 evening.
-Thunderstorms will be capable of producing strong to severe gusty
 winds, hail, and heavy rainfall. The strongest of storms will be
 in this afternoon and Friday afternoon.
&&
.DISCUSSION...This will be an active monsoon pattern starting
today through most of the weekend. The low pressure center has
entered California this morning and it will drop towards Arizona
through today and tomorrow. This system will bring dynamics,
mixture of upper level dry air, and tapping into deep monsoon
moisture for scattered to widespread thunderstorms and rain
showers. Expect strong afternoon thunderstorms and overnight to
early morning rain showers with embedded thunderstorms through
Saturday night. There will be three main hazards for today,
tomorrow, and Saturday: gusty winds, hail, and heavy rainfall.
Gusty winds: Forecasted CAPE values for today and tomorrow will
generally be 1000-1600 J/kg. Friday values will be on the higher
end of the range. Plus, there will be high lapse rates and PWAT
values will be above 1.30 inches. This points to a favorable
environment for strong gusty winds today and tomorrow afternoon.
Not to mention, the low will bring necessary dynamics, diffluence
aloft, and dry air in the mid-to-upper levels to sustain
organized thunderstorms...potentially long-live storms.
Hail: Small hail to an inch size at the most will be possible
today and tomorrow. Steep lapse rates and the high CAPE values as
mentioned before will favor hail growth. Plus, our atmospheric
temperatures will be cooler than previously seen this past
summer. Shear will be 15-30kts which is pretty impressive for our
neck of the woods. Therefore, a better environment for hail to
form and less chance for substantial melting. Expect
thunderstorms to grow rapidly this afternoon with hail first, then
becoming more heavy rainers by the end of the day.
Heavy rain: We are sitting above normal monsoon moisture for this
time of year. This has been persistent for over a week, but now we
are adding more dynamics for lifting more of that deep moisture
for heavy rainfall. Tomorrow, the low pressure center will tap
into a stream of deeper moisture from the Mexico. Our IVT values
will be 300-400 kg/m(s) leading to very saturated atmosphere for
scattered to widespread thunderstorms and rain showers.
Thunderstorms will be capable of producing 0.75"-1"+ of rain in a
short amount of time. Higher amounts can be expected in the
mountains. Therefore, a Flash Flood Watch is in effect today
through Saturday. The bulk of the heaviest will be today and
tomorrow. Overnight rain showers will persist on and off tonight
and again tomorrow night. If there is a little more clearing of
the clouds by the late Friday morning, we can expect a rapid and
strong thunderstorm growth due to heating (increasing the CAPE).
Rain showers and thunderstorms will be waning on Saturday, but
with how saturated the soils will be, it will continue to pose
flooding issues through Saturday. Turn Around, Don`t Drown!
&&
.AVIATION...Valid through 26/12Z.
SKC to FEW clouds AOA 10-12k ft AGl this morning. After 25/17Z
clouds will increase to SCT to BKN mainly KTUS eastward AOA 5-10k
ft AGL with scattered to widespread TSRA and SHRA through most of
the forecast period. Gusty and erratic winds to around 35-45+ kts
will accompany thunderstorms. SFC winds will be south-
southeasterly at 8-15 kts this morning. By 25/18Z, south-southwest
winds at 10-15 kts with gusts up to 25 kts through the remainder
of the forecast period. Aviation discussion not updated for TAF
amendments.
&&
.FIRE WEATHER...Active monsoonal pattern today through the
weekend, bringing thunderstorms and wetting rain showers. A low
pressure center will be moving through the region and tapping into
above normal moisture. Thunderstorms will be capable of producing
strong to severe level gusty winds, hail, and heavy rainfall. Rain
showers will linger through the weekend. General winds will be
southerly to southwesterly today through the Saturday with speeds
up to 15 mph and strong gusts up to 25 mph. The above normal
moisture will keep min RHS above 25 percent through most of the
weekend. Plus, temperatures will be around normal through the
weekend. Next week, temperatures will be slightly above normal
with winds less than 15 mph and min RHs 18-22 percent in the
valleys and 25-30 percent in the mountains.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
Flood Watch from 11 AM MST this morning through Saturday evening
for AZZ503-504-506>514.
Flood Watch from Friday morning through Saturday evening for
AZZ505.
&&
$$
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NWS TWC Office Area Forecast Discussion