024
FXUS65 KTWC 250312
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
812 PM MST Sun Aug 24 2025

.SYNOPSIS...Shower and thunderstorm chances continue west of
Tucson this evening, then expand to the remainder of southeast
Arizona starting Monday. Expect daily chances for showers and
thunderstorms with day to day variability on coverage and
intensity through mid week with a drying trend later in the week.
Above normal temperatures through Monday then trending down to
slightly below normal Tuesday through Thursday.

&&

.UPDATE...

Temperatures have fallen into the low to mid 90s this evening (as
of 03Z). With tomorrow`s high temperatures largely expected to
remain below 100 and keep HeatRisk much lower than previous days,
the Extreme Heat Warning has been allowed to expire as planned.

&&

.PREV DISCUSSION... /issued 156 PM MST Sun Aug 24 2025/ Latest
visible satellite imagery shows mostly clear to partly cloudy
skies east of Tucson and partly cloudy skies west of Tucson.
Scattered showers and thunderstorms have started forming in the
past hour or so across central and western Pima County and this is
the focus area for today as PWAT values range in the 1.25 inch to
1.5 inch range with MLCAPEs of 1000-1500 J/KG DCAPEs 1500-2000
J/KG. Expect a few strong to potentially severe thunderstorms
across the western deserts this afternoon into early evening with
strong winds the main concern. Areas of locally heavy rain will
also occur with the strongest storms. Otherwise, the rest of the
forecast area should remain dry into the early evening. However,
as additional moisture filters in from the south and west, there
is the potential for some overnight into early morning showers and
thunderstorms, especially across western Pima County where the
combination of higher moisture levels and lift on the north side
of an upper level trough may aid nocturnal and early morning
activity. The HRRR has been consistent showing this scenario for
numerous runs now so it`s something we`ll be watching through the
evening.

Monday is shaping up to be an active day across our forecast area as
deeper moisture will continue to spread to the north and east and
the area will still be on the north (leading) side of an upper level
trough across Sonora. With PWATs increasing to 1.2 to 1.7 inches for
central and western portions of the forecast area (Pima, Pinal,
Santa Cruz Counties), this will result in MLCAPE values of 1000-1500
J/KG. The combination of the moisture and instability with lifting
from the trough will result in more widespread convection. The
highest confidence for storms is to the south and west of Tucson
with a bit lower confidence in Tucson/eastern Pima County and points
eastward. Note that locales close the NM border will remain mostly
dry with less moisture out that way. Storms should initiate
generally across Santa Cruz and south central Pima County then move
to the west and northwest with outflows helping kick off new storms.
Expect both severe wind and localized flash flood threats Monday.
Per coordination with SPC and WPC, WPC has placed portions our of
area in SLGT risk for Excessive Rainfall on Monday (and Tuesday)
with the SPC highlighting a MRGL risk for severe thunderstorms
(wind) from Tucson south and westward. Decided against hoisting any
flood watch headlines at this time as confidence on widespread flash
flooding still a bit low.

Tuesday will be highly dependent on what happens Monday. There will
still be well above normal moisture across our forecast area with
upper level troughing pushing through in the southerly flow aloft.
The focus on Tuesday might end up shifting to areas generally east
of Tucson which aren`t expected to get as much on Monday.

Drier southwest flow aloft will start to move in on Wednesday and
this should help diminish areal coverage of activity. Current
PoPs are in the 30 to 40 percent range but if the drying trends
continue we, we`ll have to continue to lower them even more. This
drying trend should tend to hold Thursday through Saturday for
most of the forecast area (except possibly SE Cochise County)
before additional moisture tries to work back in later next
weekend.

Temperatures will lower to seasonal normal levels Monday and then
drop to below normal Tuesday through Thursday before warming back up
to several degrees above normal next weekend.

&&

.AVIATION...Valid through 26/00Z.
SCT-BKN 9k-12k ft AGL. Widely scattered -SHRA/-TSRA west of KTUS
btwn thru 25/03z then isolated -SHRA/-TSRA thru 25/18Z. Aft 25/18Z
scattered-numerous SHRA/TSRA from KOLS/KTUS westward. Expect gusty
and erratic winds with any TSRA otrw SFC winds will generally be E-
SE less than 12 kts through 25/18Z. Thereafter, sfc winds mainly
WLY/NWLY with the exception of locales near the NM border. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Expect daily chances for rain showers and
thunderstorms through mid week with diminishing chances later in the
week into next weekend. Temperatures will be running above normal
again this afternoon with an Extreme Heat Warning in effect for the
lower elevations. Winds will generally remain less than 15 mph with
the afternoon gustiness this week. Min RHs will be 15-20 percent in
the low elevations and 20-30 percent in the mountains through the
weekend. Deep monsoon moisture early this week to provide higher
wetting rain chances and coverage as well as better min RHs and
below normal temperatures.

&&

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

Update...Edwards

Visit us on Facebook...Twitter...YouTube...and at weather.gov/Tucson