066
FXUS65 KTWC 202021
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
121 PM MST Mon Oct 20 2025
.SYNOPSIS...Above normal high temperatures through Wednesday and
near normal or slightly below normal Thursday into the weekend. Dry
conditions will also prevail through most of the upcoming week. The
exception will be Wednesday where there is a slight chance of
showers for the mountains northeast of Tucson.
&&
.DISCUSSION...Sunny skies this afternoon across southeast Arizona
with high temperatures above normal resulting in minor HeatRisk.
A ridge of high pressure has been building over northern Mexico
the last few days while a storm system sits off the coast of
southern California. The higher pressure will continue to support
minor HeatRisk and above normal temperatures through Wednesday
before the storm system approaches. Latest NBM probabilities for
reaching 90 degrees in the Tucson Metro tomorrow and Wednesday is
85 percent and 75 percent respectively. Remember to stay hydrated
even as fall outdoor activities become more popular. Minor
HeatRisk means those who are particularly sensitive to heat remain
at risk for heat related illnesses.
Wednesday, as the storm system moves onshore the winds will turn to
the south. Southerly flow ahead of the approaching storm system will
help bring above normal moisture into the region supporting clouds
and a chance of showers. However, the best lift from the storm
system appears to stay over northern Arizona, so confidence is lower
for precipitation across southern Arizona. That being said, there is
still a slight chance of showers (10-15%) stretching from the
Mogollon Rim south into the White Mountains and Sky Islands of
Graham/Greenlee counties on Wednesday as terrain may help influence
forcing. Overall, little to no impacts from rain are expected with
QPF remaining very light (less than 0.05") and focused in the
mountains.
The passage of the storm system Wednesday into Thursday may result
in locally gusty southwest winds for Santa Cruz County. However,
latest NBM probabilities for wind gusts over 25 mph on Wednesday are
low (10-30%), so only localized nuisance impacts are anticipated.
Thursday into Friday, the storm system will push into the
southern/central Rockies and eject into the southern plains
leaving a slightly cooler airmass in its wake. Saturday through
Monday temperatures will return to near normal for southeast
Arizona.
&&
.AVIATION...Valid through 22/00Z. SKC thru most of the valid
period with FEW-SCT high clouds after 21/21Z. SFC winds WLY/NWLY
at 5-10 kts this afternoon and early evening. Otherwise, SFC winds
light and variable. Aviation discussion not updated for TAF
amendments.
&&
.FIRE WEATHER...Minimum RH values will be in the 15-25 percent
range in the valleys through the work week, except Wednesday when RH
values increase by 5-10 percent. 20-foot winds mainly 15 mph or
less, with occasional gusts to 20-25 mph. Chance for breezy winds
Wednesday as a weather system moves through. High temperatures will
2-6 degrees above normal through the middle of the week, then cool
back down to around normal. Expect dry conditions over the next 7
days with the exception the mountains northeast of Tucson Wednesday,
which will see up to a 20 percent chance for showers.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...None.
&&
$$
DVS
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