469
FXUS65 KTWC 032021
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
121 PM MST Fri Oct 3 2025

.SYNOPSIS...A moisture increase east of Tucson today will result in
a slight chance of showers and thunderstorms this afternoon into the
evening hours tonight. Dry conditions this weekend into early next
week. High temperatures 7 to 9 degrees above normal today, lowering
to near normal this weekend. Breezy southwest winds are expected
this weekend as a system moves to our north. High temperatures warm
again to 3 to 5 degrees above normal next week.

&&

.DISCUSSION...Very little change in the forecast package versus 24-
hours ago except in the short term. The large scale pattern has the
high pressure ridge shifting eastward as a Pacific storm system and
associated trough dig south through north central California. The
upper low will shift eastward into central Nevada tonight as the
high pressure ridge continues to shift east into Texas and the mid
Mississippi Valley. The low will then move eastward across the Great
Basin over the weekend, with near zonal flow across the desert
southwest. By early next week, the flow aloft turns southwesterly
across the region.

The biggest changes in the forecast package are for the today and
tonight periods in regards to precipitation chances. Blended total
precipitable water imagery shows PWAT`s currently in the 0.65" to
0.85" range, with higher amounts of over an 1" across northern
Sonora Mexico. The models indicate this moisture will continue to
get pulled northward in advance of the trough axis this afternoon
and tonight. This will result in scattered to broken cloud cover
from Tucson eastward, as well as isolated showers and thunderstorms
primarily over Cochise, Graham and Greenlee counties. The Latest hi-
res models and U of A WRF show convection persisting across eastern
areas until about 10 pm MST this evening. Wind gusts to 35+ mph will
be possible with the strongest storms. Otherwise, high temperatures
today will top out 7-9 degrees above normal. High temperatures will
be in the upper 90s to right around 100 degrees from Tucson
westward, with upper 80s to mid 90s across Santa Cruz, Cochise and
Graham counties.

As the storm system tracks across the Great Basin over the weekend,
temperatures cool down to near seasonal normals, with highs in the
upper 80s to lower 90s from Tucson westward and highs in the 80s
across Santa Cruz, Cochise and Graham counties. This system will
also bring gusty southwest winds to the area especially Saturday
afternoon. Wind speeds will generally be 12-18 mph with gusts to 20-
30 mph from Tucson eastward. Peak wind gusts on Saturday will be
30-35 mph across portions eastern Santa Cruz and Cochise counties.

By early next week, the storm system will track east into the
central plains and southwest flow aloft will prevail across the
region. This will lead to warmer temperatures and highs 2-4 degrees
above normal.

For mid to late next week, high uncertainty remains in regards for
the potential of tropical moisture advecting into the area. The
latest CPC 6-10 day/8-14 day precipitation outlooks are 50-70% above
normal across the area. It will all come down to the track of EP99
and the position of west coast trough next week. The latest grids
have shifted precipitation chances later in the week, with slight
chance pops next Thursday and Friday.

&&

.AVIATION...Valid through 05/00Z.
SCT-BKN clouds at 10k-12k ft AGL with ISOLD -SHRA/-TSRA mainly east
of KTUS thru 04/05Z, then clearing skies thru end of valid period.
Wind gusts to 35+ kts with -TSRA. Otherwise, SLY/SWLY SFC wind at 10-
14 kts and gusts up to 20 kts thru 04/03Z. SFC wind variable and
terrain driven at less than 10 kts between 04/03Z and 04/16Z.
Increasing SLY/SWLY SFC wind aft 04/16Z, with speeds of 12-18 kts
and gusts to 22-28 kts aft 04/19Z, with the strongest SFC wind
southeast of KTUS in the vicinity of KALK and KDUG. Aviation
discussion not updated for TAF amendments.

&&

.FIRE WEATHER...There will be a slight chance of showers and
thunderstorms mainly east of Tucson through this evening. Dry
conditions will then prevail across southeast Arizona this weekend
into at least early next week. 20-foot winds will be 15 mph or less
and terrain driven today. A storm system will then move by to our
north this weekend resulting in increasing southwesterly winds. 20-
foot winds will be 12-18 mph and gusts to around 30 mph Saturday,
with the strongest winds southeast of Tucson across portions of
Santa Cruz and Cochise counties. Min RH values in the valleys will
be in the 15-30 percent range today, lowering to 12-20 percent over
the weekend through early next week. RH values in the mountains will
generally be in the 25-35 percent range. High temperatures will be 7-
9 degrees above normal today, cooling to around normal this weekend,
then warming back up to 3-5 degrees above normal early next week.

&&

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

&&

$$

Zell

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