Marshall Gulch Picnic Area, Arizona Weather Forecast Discussion

729
FXUS65 KTWC 271601
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
901 AM MST Sat Sep 27 2025
.SYNOPSIS...Drier air has moved in across the area which will
limit the chance of showers and thunderstorms this weekend. High
temperatures will be below normal this weekend then warm next
week under dry conditions.
&&
.DISCUSSION...A beautiful and picturesque morning across Southeast
Arizona with temperatures this morning ranging from the 60s to the
east and southeast of Tucson to the 70s from Tucson West. The
latest satellite imagery indicated plenty of cumulus and
stratocumulus clouds across the forecast area, with pockets of
fog observed across southern Cochise and up into the Sulphur
Springs Valley. The Dense Fog Advisory that was in effect this
morning has been allowed to expire at 9 AM with the fog starting
to erode.
Otherwise...the upper pattern this morning is still dominated by a
strong upper low positioned across southern California/extreme
southwest Arizona. A substantial dry slot had rotated along the
southern periphery of this feature into Southeast Arizona. This
has resulted in the latest GOES precipitable water imagery
depicting low PWAT values between 0.55 and 0.65 inches southeast
and east of Tucson, around 0.85 inches near the Tucson Metro...and
deeper moisture to around 1.15 inches across western and central
Pima and southeast Pinal counties. Although the upper pattern will
result in a decent diffluent pattern aloft over SE Pinal/Graham
and Greenlee counties today, the drier air will limit the overall
coverage of thunderstorm activity from Tucson to the southeast and
east today. Isolated to scattered thunderstorms will still be
possible west and northwest of Tucson and is still supported by
the 27/12Z HREF ensemble members.
&&
.PREV DISCUSSION... /issued 308 AM MST Sat Sep 27 2025/
Mostly clear conditions early this morning. Water vapor imagery
showed quasi-stationary upper low over SE CA. This system advected
much drier air across southeast Arizona over the past 24 hours
with PWAT values down below an inch across much of the area this
morning. With drier atmosphere in place today, only a few storms
are expected this afternoon with PoPs mostly less than 30%. The
Flash Flood Watch that was in effect until this evening was
cancelled late last night. The upper low opens up Sunday as it
moves across northern Arizona. Slight chance of afternoon
showers/storms mainly northeast of Tucson. High temperatures this
weekend will run 2 to 5 degrees below normal.
Dry and warmer next week as we close out September and the 2025
Monsoon and welcome in October.
&&
.AVIATION...Valid through 28/00Z. SCT-BKN 6k-10k ft AGL. ISOLD -SHRA/-TSRA
after 19Z, with the best coverage north and west of Tucson. SFC winds
SELY less than 10 kts thru 27/19z, then SLY to SWLY at 10-15 kts with
gusts up to 25 kts thru 28/03z, then SELY less than 10 kts. Aviation
discussion not updated for TAF amendments.
&&
.FIRE WEATHER...Isolated showers and thunderstorms this weekend.
Generally winds will be south to southwest through next week with
speeds up to 15 mph and gusts up to 20-25 mph. The above normal
moisture will keep min RHs above 25 percent through most of the
weekend. Temperatures will be slightly below normal through the
weekend. Next week, temperatures will warm to 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...NONE
&&
$$
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NWS TWC Office Area Forecast Discussion