Tumacacori Arizona Weather Forecast Discussion

262
FXUS65 KTWC 090900
AFDTWC
Area Forecast Discussion
National Weather Service Tucson AZ
200 AM MST Thu Oct 9 2025
.SYNOPSIS...
Partly to mostly cloudy skies persist across southeastern Arizona
as tropical moisture has set into the area. Isolated chances for
showers and thunderstorms continue through Friday, then widespread
chances arrive this weekend with a threat of heavy rain. Rain
chances continue into Tuesday of next week. Temperatures transition
from above normal through Friday to below normal by the end of
the weekend.
&&
.DISCUSSION...
The water vapor picture early this morning features an
increasingly amplified pattern, with a closed Pacific low sitting
off the northwest coast, a building upstream ridge, and Tropical
Storm Priscilla off the southwest coast of the Baja Peninsula.
Speaking of that area of the Pacific, the National Hurricane
Center highlights the active region with TS Octave still located
south of Priscilla and Invest 90E south of southern Mexico.
Precipitable water has increased notably over the last 24 hours
across southeastern Arizona, now over 1.25-1.5 inches according to
latest satellite readings and the 00Z Tucson upper air observation.
Southeasterly low- mid level flow will continue to push tropical
moisture into southeastern Arizona over the coming days. Until the
Pacific low can make its way inland, this moisture will lack a
triggering mechanism to produce much more than isolated showers
and widespread cloudiness. This changes on Saturday as the low is
expected to open and cross inland over the Great Basin. Mid-level
height falls will overspread southeastern Arizona and combined
with the well- above normal moisture content in place, produce
widespread rain chances through the weekend.
Model QPF for this weekend (and into early next week) has been a
challenge over the last several days. Notably with recent runs of
the deterministic GFS (or a few of the GEFS ensemble members)
producing truly incredible rainfall totals across portions of
southeastern Arizona. The suite of ensemble solutions however has
clustered mainly on the more reasonable side and continues to do
so with the 00Z run. The current forecast continues to advertise
1 to 3 inch totals through Monday, with lesser amounts in western
Pima. That still leaves room for isolated greater totals,
especially atop mountains and across southern locations of Santa
Cruz and Cochise counties. Depending on where bands of heavier
precipitation develop, isolated 3 to 5 inches is possible. This
isn`t to say there isn`t still a window for a wetter outcome
across the board, especially if a secondary push of richer
moisture arrives late Sunday and Monday. If it trends in that
direction over the next 24-48 hours, a hydrology headline may be
needed. However at this point confidence in that kind of scenario
is low enough to preclude headlines for southeastern Arizona.
Periods of rain likely last through Monday, then drying begins
Tuesday with lingering moisture keeping rain chances in the
forecast through Tuesday evening.
Temperatures are expected to trend down with this active pattern.
Highs will transition from 3-7 degrees above normal today and
Friday to below normal by the end of the weekend.
&&
.AVIATION...Valid through 10/12Z.
SCT-BKN ceilings at 7k-10k feet and BKN-OVC 11k-14k feet through
the forecast period, as well as isolated -SHRA. Surface winds east
to southeast 8-14 kts with gusts to 20-25 kts in most locations,
with gusts to 30 kts in the upper Gila River Valley near KSAD.
Aviation discussion not updated for TAF amendments.
&&
.FIRE WEATHER...
High temperatures will be 4-7 degrees above normal
through Friday, falling to 3-9 degrees below normal Saturday into
the middle of next week. Tropical moisture moving northward through
Mexico will result in increasing chances for widespread showers and
isolated thunderstorms through at least early next week. There will
be the potential for widespread rainfall accumulating over several
days, Saturday into Tuesday. This increase in moisture will raise
min RH values to at least 25+ percent in the valley`s, with values
in the Saturday through Tuesday time frame at 40+ percent. 20-foot
wind speeds will generally be 15 mph or less through early next week
and gusts to 20-25 mph, with the potential for some gusts to around
30 mph in the upper Gila River Valley through Friday.
&&
.TWC WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
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NWS TWC Office Area Forecast Discussion