821
FXUS65 KPSR 112337
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
437 PM MST Tue Nov 11 2025

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- Unseasonably warm weather will persist through the middle of this
  week with high temperatures around 5 to 8 degrees above normal.

- A strong storm system is expected to arrive by Friday bringing
  gusty winds, widespread accumulating rainfall, and mountain
  snow.

- Temperatures are expected to cool well below normal this weekend
  with lower desert highs falling into the 60s and 70s and lows in
  the 40s and 50s.

&&

.SHORT TERM /Today through Thursday/...
The upper level ridge continues to be the dominate feature over
the desert SW, driving temperatures today to remain 7-10 degrees
above normal, as 500mb heights are between 586-588dam, which is
above the 90th percent of climatology for this time of year. These
heights will remain relatively consistent over the next couple of
days with afternoon highs in the mid 80s in the Phoenix Metro
areas and mid to upper 80s in the Yuma/El Centro areas.

The upper level ridge will weaken and traverse eastward throughout
the week, during which cirrus cloud decks will begin to
infiltrate the forecast region ahead of an upper level trough to
the west. These cloud decks will progressively thicken in the
later portions of the week as the trough continues to slowly
approach. This increased cloud coverage in conjunction with the
incoming troughing feature will bring the most noticeable
temperature decrease by late Thursday into Friday, where
temperatures look to decrease by 5-8 degrees. However, there is
uncertainty is the exact timing of the trough into the region.
This can be seen in the NBM forecasted highs, as the spread
between the 25th and 75th percentile is now 8 degrees.

&&

.LONG TERM /Friday through Tuesday/...
We then turn our attention to a very active weather period
beginning on Friday and persisting into the weekend. Since the
last forecast issuance, deterministic models and ensemble members
have now shifted to a slower and deeper track of the upper low
through SoCal on Friday. This solution is now being favored by
more than half of the GEFS and EPS members as well as the
deterministic GFS and ECMWF. If this solution were to come to
fruition, our forecast area would see a more prolonged period of
precipitation beginning late Thursday across southeast CA and
spreading ewd into southcentral AZ on Friday and Saturday. The
latest WPC 5-day QPF totals have increased dramatically across
southcentral AZ with widespread storm totals up to 1.00"-1.50".
This uptick in QPF is also reflected in the mean of the GEFS which
is showing a storm total of around 1.00" for Phoenix. Another
added element to this forecast will be increasing chance for
thunderstorms especially Friday night into early Saturday as mid-
lvl lapse rates steepen ahead of the approaching cutoff low. The
core of the closed low is projected to pass over central AZ late
Saturday into Sunday which will bring an end to the precipitation
for the lower deserts, but a few light showers could persist over
the AZ high terrain. It is important to note that we are a few
days out and there is still time for models to shift. For now,
precipitation chances peak at 20-40% for southeast CA and southwest
AZ and up to 40-60% for southcentral AZ late Friday into Saturday.

As the upper-low progresses through the forecast area, we will
see a noticeable drop in temperatures. Highs temperatures are
expected to fall from the mid 80s on Thursday to upper 60s to low
70s on Friday. Well below normal temperatures will carry into the
weekend making it feel much more fall-like. Overnight lows will
also tumble into the upper 40s to low 50s with some locations
across the high terrain areas NE of Phoenix bottoming out in the
upper 30s on Sunday morning. Well below normal temperatures will
likely persist into early next week as long range models indicate
a reinforcement of the upper-lvl trough Intermountain West Monday
into Tuesday. Although uncertainty is higher, this secondary
trough could also bring another round of precipitation to the
Desert Southwest by the middle of next week.

&&

.AVIATION...Updated at 2336Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns are anticipated at all terminals
through Wednesday under BKN high clouds. Winds will remain very
light and at times calm, while still following diurnal tendencies.

&&

.FIRE WEATHER...
Warm and dry conditions with above normal temperatures will
persist through Thursday before a strong weather system brings
cooler temperatures and chances for wetting rains to the region as
early as Friday and into the weekend. Over the next couple days
min RHs will range between 15-20% before improving to 35-40% on
Friday and remaining above 35% through the weekend. Overnight
recoveries will remain poor to fair through Thursday but improve
to an excellent category by Friday night. Winds will be light,
generally less than 15 mph and follow typical diurnal patterns
through most of this week, however breezy to locally windy
conditions are expected to develop across the western districts
Thursday and Friday where gusts could reach 25-35 mph.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

SHORT TERM...Ryan
LONG TERM...Salerno
AVIATION...Benedict
FIRE WEATHER...Ryan/Salerno