367
FXUS65 KTWC 061004
AFDTWC

Area Forecast Discussion
National Weather Service Tucson AZ
304 AM MST Mon Oct 6 2025

.SYNOPSIS...

Expect a warming trend this week as high temperatures rise above
normal through the work week. Moisture returns late this week,
initially providing increased cloud cover and very slight chances
for showers to end the work week. Increasing chances for rain
showers then arrive this weekend.

&&

.DISCUSSION...

Broad troughing from the past weekend will give way to
southwesterly flow and building mid-level heights from a westward
shifting ridge this week. Temperatures rise with this pattern
shift as highs become 4 to 8 degrees above normal into the weekend.

By mid-week, the upper level pattern will be characterized by the
aforementioned high centered over the southern plains and north-
central Mexico, with a Pacific trough dropping south off the
northwest coast. Hurricane Priscilla is forecast to continue to
track north-northwest, becoming situated off the western Baja
coast mid-week. Moisture advection associated with both the
impinging ridge and the approaching hurricane will likely bring
well above normal precipitable water values Thursday into the
weekend. Global model ensembles have had good agreement in
widespread pwats exceeding an inch through this period, however
the run to run trend over the last 24 hours has seen the higher
end solutions increase notably with greater coverage of 1.25 to
near 1.5 inch values. Synoptic scale forcing however remains weak,
at least initially. While increased cloud cover is likely
Thursday and Friday with potentially a smattering of shower
chances, the low likelihood of adequate instability and the nearby
ridge keeps forecast chances on the low end. That will change
however this weekend with the likely approach and crossing of the
Pacific trough. Notable differences remain in timing and trough
depth, painting broad 20-40 percent precipitation chances over the
weekend, but guidance remains fairly consistent in the occurrence
of this trough passage bringing widespread rain chances to the
region. As lead time diminishes and more details emerge about the
likely timing of the trough and associated frontal passage,
forecast precipitation chances at some point should increase.
Additionally there remains the potential for Hurricane Priscilla
to take a turn northeast and provide additional moisture to the
precipitation event, which could bring hydrology concerns if well
timed with the trough. There are a good amount of details to be
worked out in the above discussion, however the bottom line is
that increasing rain chances this upcoming weekend should be
monitored. Finally, this moisture increase and active end of the
seven day period should bring temperatures from above normal into
the weekend to near to potentially below normal by the late
weekend into next week.

&&

.AVIATION...

Mainly SKC with increasing clouds AOA 20k feet over far
southeastern locations late this afternoon and evening. Surface
winds becoming southerly 5-10 knots after 06/18Z then light and
terrain driven after 07/03Z. Aviation discussion not updated for
TAF amendments.

&&

.FIRE WEATHER...

Minimum relative humidities mainly 12-20 percent through Tuesday.
Winds mainly on the lighter side to start the work week, with
potentially gusty southeasterly winds in the Gila River Valley
Wednesday. A push of moisture should begin to bring up minimum
relative humidities through the second half of the week, however
rain chances remain low through the remainder of the work week
becoming 20-40 percent next weekend.

&&

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

$$

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Aviation...Edwards
Fire Weather....Edwards

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