608
FXUS65 KPSR 012321
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
421 PM MST Mon Dec 1 2025

.UPDATE...Updated 00z Aviation Discussion...

&&

.KEY MESSAGES...

- Dry and mostly tranquil conditions will exist through the next
  few days with some occasional breeziness for the Lower Colorado
  River Valley this afternoon.

- Weak low pressure will dive across the Great Basin during the
  middle portion of the week potentially sparking some isolated
  shower activity over higher terrain areas of central and eastern
  Arizona.

- Temperatures through the week will cool slightly, but will be
  generally steady, hovering around normal levels for this time of
  year.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...
The Desert Southwest currently finds itself caught between a
positivley-tilted trough moving over the Southern Plains and a high
amplitude ridge over the eastern Pacific. Even though heights
aloft will be on the rise as the influence of the upper-level high
pressure reaches out towards the Great Basin, cool, and dry
northerly flow will keep temperatures generally in the upper 60s
to lower 70s for lower desert areas. The somewhat enhanced
pressure and thermal gradients will result in some occasional
breeziness, with gusts around 25 mph being most common for
portions of the Lower Colorado River Valley this afternoon.
Persistent cool northerly to northwesterly flow aloft will help
nudge temperatures down a degree or two for Tuesday.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Models continue to trend away from any impactful weather later
this week with a second Pacific trough now expected to take a more
northerly track. Ensembles are now in very good agreement the
next system for later Wednesday and Thursday will be much like the
first progressive system. Even compared to model runs yesterday,
the system shows a more eastward and northerly track shift
bringing the bulk of the energy across northeastern Arizona.
Additionally, the fact the trajectory of the trough is completely
inland and it is now likely to take a shallower track through our
region moisture will be even more limited than previously
expected. As are result, NBM PoPs have dropped dramatically since
yesterday with PoPs dropping to below 10% for all of the western
deserts and even the western half of the Phoenix metro. Depending
on the exact track of the system, the Arizona high terrain may
still see some light shower activity, but expected QPF amounts
have fallen below 0.05".

Temperatures should also dip a bit further with the passage of
the trough with lower desert highs falling more into the mid to
upper 60s for Thursday and Friday. Guidance also heavily favors a
more expansive ridge setting up over the eastern Pacific later
this week with a fairly likely chance of a portion of the ridge
will edge into our region by the weekend. Although the ridge is
shown to flatten out over the weekend, the weather pattern may
support the ridge to rebuild again and push farther into our
region during the first half of next week. We have high forecast
confidence in dry conditions prevailing well into next week with
temperatures eventually warming to above normal.

&&

.AVIATION...Updated at 2320Z.

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

No major aviation weather concerns under some passing high clouds
can be expected throughout the TAF period. Wind speeds will
generally be aob 7 kts throughout the period. North to northwest
winds will be common at both KIPL and KBLH. At the Phoenix area
terminals, generally light and variable winds will be common
through early this evening before shifting out of the east later
this evening. Confidence is increasing of winds temporarily
shifting out of a light west to southwest direction at KPHX
between the 09-13z time frame and thus a TEMPO group has been
added to the latest TAF package to reflect this shift. Otherwise,
a more typical diurnal wind pattern is expected to develop on
Tuesday.

&&

.FIRE WEATHER...
Dry conditions will continue to prevail for the bulk of the region
this week as two mostly dry weather systems pass near or through
portions of the region. Today`s weak weather system will only
bring breezy northerly winds across the Lower CO River Valley and
slightly cooler temperatures. Another weather system for late
Wednesday and Thursday may bring light precipitation chances, but
mostly to higher terrain areas. Humidities this week will stay
elevated with MinRHs mostly ranging between 25-35% much of the
time, with good to very good overnight recoveries. Winds are
expected to stay light across the eastern districts, while another
round of breezy conditions will be possible across the western
districts Wednesday and Thursday.

&&

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

$$

SHORT TERM...RW
LONG TERM...Kuhlman
AVIATION...Lojero
FIRE WEATHER...Kuhlman