619
FXUS65 KTWC 231537
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
837 AM MST Sat Aug 23 2025

.SYNOPSIS...Daily chances for showers and thunderstorms with day
to day variability on coverage and intensity. Above normal
temperatures through the weekend and then trending down to near
normal by the start of next week. An Extreme Heat Warning in
effect until Sunday evening for the greater Tucson area to
southeastern Pinal county.

&&

.UPDATE...Latest GOES Total PWAT imagery tells the story nicely this
morning with a big spread in PWATs from east to west, as eastern
locales in Cochise County see much drier conditions with PWAT around
0.6 inches and much wetter conditions across central and western
Pima County with PWAT values around 1.5 inches. Mid/upper level high
pressure aloft is located across northern Arizona with easterly flow
aloft continuing. Not much change in thinking from the mid shift
this morning as the latest CAMs/HREF continue to show scattered
storms this afternoon into evening across central and western Pima
County. These will produce strong winds (DCAPE is 1500-1800 J/KG)
and locally heavy rainfall under the stronger storm cores. From
Tucson eastward, dry conditions will prevail with the exception of
the White Mountains where a few showers and thunderstorms are
possible. Current grids are in good shape. No forecast updates this
morning.

&&

.DISCUSSION...The western half of the forecast area this morning
has seen a jump in surface dewpoints into the 60s, thanks to last
nights thunderstorm complex west of Hermosillo. Debris clouds
from this complex was spreading east across the area. Easterly
flow continues across the area this morning with the upper high
centered near the 4 corners. PWATs this morning ranged from 0.60"
near the AZ/NM border to 1.70" over western Pima county.

Low-grade monsoon this weekend with the main area of concern both
days being west-southwest of Tucson. There will be an isolated
risk of severe thunderstorms late this afternoon into this
evening, especially west of Sells to Ajo, where HREF neighborhood
probabilities have a 10% chance of wind gusts greater than 58 mph
and then a 50% chance of wind gusts greater than 35 mph on
Sunday. Highs remaining on the warm to locally hot side for late
August with Extreme Heat Warning in effect for southeast Pinal
county and eastern Pima county.

Next week: As the upper high moves east into Texas, flow aloft
become more southerly, allowing the influx of deeper monsoonal
moisture through mid-week. This will lead to the potential for
an uptick in areal coverage of showers and thunderstorms with
day-to-day variability of coverage through Thursday then drier SW
flow aloft starts to push moisture out again on Friday. The way
this monsoon has been behaving confidence on next week is on the
low to medium side.

&&

.AVIATION...Valid through 24/12Z.
Debris cloudiness AOA 15k ft AGL will gradually diminish thru
23/17z. Aft 23/18z, FEW-SCT 9k-12k ft AGL with ISOLD -SHRA/-TSRA
west of KTUS. SFC winds will generally be E-SE less than 12 kts
through the forecast period. Expect gusty and erratic winds with
any -TSRA. Aviation discussion not updated for TAF amendments.

&&

.FIRE WEATHER...Expect daily chances for rain showers and
thunderstorms into next week with day to day variability of
intensity and coverage of storms. Temperatures will be running
above normal this weekend with an Extreme Heat Warning in effect
for the lower elevations. Winds will generally remain less than
15 mph with the afternoon gustiness into next 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 will return
early next week to provide higher wetting rain chances and
coverage as well as better min RHs and below normal temperatures.

&&

.TWC WATCHES/WARNINGS/ADVISORIES...
 Extreme Heat Warning until 8 PM MST Sunday for AZZ504>506.

&&

$$

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