440
FXUS65 KPSR 202306
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
405 PM MST Tue Jan 20 2026

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- High pressure will continue to be the dominant feature over the
Desert Southwest resulting in above-normal temperatures and dry
conditions through the next few days.

- Weak low pressure will meander its way toward the region by the
weekend bringing cooler temps and chances for rainfall.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
Current objective analysis reveals high amplitude ridging continuing
to dominate much of the western CONUS while a shortwave trough
embedded in the broader flow pattern dives south toward the Northern
Rockies. The latter of these features, plus another follow on
disturbance, will begin to erode the stubborn area of high pressure
over the next few days, but dry conditions with above-normal
temperatures will continue. The only impact expected as these
duplicate shortwaves shave away at heights aloft is very minimal
downtrend in day-to-day temperatures. Highs this afternoon for lower
desert locations will range between 71-78 degrees before falling to
between 70-75 degrees by Thursday.

The breakdown of the ridge will also allow for the advancement of an
Eastern Pacific disturbance toward the West Coast during the latter
half of the week. Moisture aloft out ahead of this system will
translate to increasing cloud cover as early as Wednesday morning.
Moisture will continue to increase heading into Thursday, saturating
the column from the top down, so other than some possible virga, the
dry sub-cloud layer will keep conditions at the surface quiet during
this timeframe. These increasing clouds will also aid in the
previously-mentioned cooling trend. Better moisture in the mid to
lower levels will begin to be pulled into southern Arizona by late
Thursday, setting the stage for some potential rainfall for the end
of the week.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Moisture across the area should peak from Friday afternoon through
Friday night with the best moisture likely being focused across
southeast Arizona. Model trends over the last couple of days have
leaned toward the more bullish case for this weather system bringing
rainfall to at least portions of our region. Despite the center of
the low missing our area to the south and it weakening by the time
it reaches northern Baja, we are likely to see most of our forcing
for precipitation from a combination of the upper jet and low level
orographic lift. This is not exactly an good recipe for widespread
rainfall, but it should be enough to bring a period of mainly light
showers from as early as Friday afternoon through at least Saturday
morning. Initial dry air in the low levels should limit the rainfall
during the first half of the event with the best chances for
measurable rainfall likely occurring during the overnight hours
Friday night. There are also some indications of some weak
instability during the daytime hours Saturday if the cold core is
close enough to southern and/or central Arizona. This could lead to
some additional isolated to scattered shower activity on Saturday.
Forecast rainfall for this event is expected to be fairly light with
the most recent guidance showing upwards of a 0.10" across the
Phoenix area to 0.25-0.50" for the eastern Arizona high terrain.
Since this will again be a fairly warm weather system, snow levels
are expected to mostly stay above 7000 feet.

Upper level ridging is then favored to quickly push into the region
from the west on Sunday with dry air surging in from the north by
Sunday afternoon. As high pressure and dry air settles over the
region early next week, we are likely to see the near normal
temperatures on Friday-Sunday quickly trend upward. Guidance
suggests we should see a return of above normal temperatures by
around next Tuesday or Wednesday.

&&

.AVIATION...Updated at 2305Z.

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

No major weather issues will exist through Wednesday evening under
thickening high cirrus decks. Behavior of wind speeds and directions
will be similar to the past 24 hours featuring muted
diurnal/nocturnal variation with speeds under 10kt. Extended periods
if nearly calm conditions will be common.

&&

.FIRE WEATHER...
Dry conditions with above normal temperatures will persist through
mid week. Daily MinRH values are expected to remain between 15-20%
each day with overnight recoveries of 30-60%. Winds will overall be
light through the period with only some periodic light breeziness
across the Lower CO River Valley and over the Arizona high terrain.
The weather pattern will change late in the week to allow for cooler
temperatures, an increase in humidities and rain chances by Friday
or Saturday.

&&

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

&&

$$

SHORT TERM...RW
LONG TERM...Kuhlman
AVIATION...18
FIRE WEATHER...Kuhlman