872
FXUS65 KPSR 172036
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
135 PM MST Mon Nov 17 2025

.KEY MESSAGES...

- Another large Pacific weather disturbance will bring the next
opportunity for rain Tuesday and Wednesday with additional chances
likely arriving later in the week.

- Temperatures this week will hover below the seasonal normal with
readings around 10 degrees below normal during the middle of the
week.

&&

.SHORT TERM /Today through Wednesday/...
The North America flow pattern will favor increased amplification
and partial blocking over the next 72 hours with mean troughing
favored over the western Conus. Early afternoon WV imagery shows
this pattern already coming to fruition given deep negative height
anomalies along the northern California coast and the development of
an intense meridional jet on the western periphery of this wave.
This jet core combined with vorticity rotating into the deepening
trough base well offshore should ensure the upstream coastal
California wave continues to dig southeast while detaching from the
northern stream jet flow. This partially cutoff circulation should
wobble over southern California through Wednesday with several
vorticity centers within the larger gyre producing forced ascent
while tapping an anomalous southerly stream of higher PWATs.

All modeling suites continue to exhibit excellent consistency with
respect to the initial evolution of features this evening and
overnight resulting in elevated rainfall chances through south-
central Arizona. While still well removed from the vorticity centers
and cold core of the upstream system, the formation of a strong
midlevel jet is already underway across southern Arizona downstream
of incoming height falls. Satellite and radar already depict the
classic signs of elevated warm advection near the international
border, and confidence is excellent that this moist isentropic
upglide around the 300K layer will expand and lift through the
central CWA this evening and overnight. While MUCape is limited to
only around 100 J/kg with marginal lapse rates, a few embedded
elevated storms are possible with the upglide and strengthening
ascent. However, most locations should only experience scattered
showers

As dynamics increase Tuesday with a notable vorticity lobe pivoting
towards the lower Colorado River valley, a steep cold front will
surge towards through SE California towards the Colorado River with
pronounced southerly flow being maintained in the warm sector over
south-central AZ. While some measure of drying should surge into SE
California, vorticity forced ascent combined with frontal convergence
within a moist environment over Arizona appear vary favorable for
waves of showers and embedded storms throughout much of the day.
Given the approaching cold core and dynamic lift, lapse rates should
steepen while boundary layer mixing ratios near 7 g/kg are advected
poleward. Pockets of MLCape near 500 J/kg seem a reasonable forecast
near peak heating resulting in isolated instances of heavy rainfall
and small hail given freezing levels falling below 7K ft. All told,
HREF mean rainfall amounts through Tuesday night of 0.10-0.50"
across lower elevations seems appropriate with non-isolated higher
amounts around 1.00" likely relegated to the foothill upslope
communities north of Phoenix.

The slow forward progression to this cutoff low adds additional
uncertainty to the forecast Wednesday as the low level cold front
and moisture plume shifts towards eastern Arizona, yet the upper
cold core and energy only advance into SE California Wednesday
afternoon. Additional showers are likely (better than a 60% chance)
through much of the eastern CWA though forecast soundings indicate
little remaining instability with nearly moist, adiabatic atmospheric
profiles. As a result, the most likely outcome is extensive thick
clouds throughout the day with several showers lifting along the
cold front and tied to sheared vorticity within the cyclonic jet
corridor. Other than the rainfall chances, unusually cool
temperatures will be notable with locations around the Phoenix metro
struggling to even reach 65F (daily normals are around 75F and the
last time KPHX failed to reach 65F was March 14th). Showers should
gradually abate Wednesday evening as the cutoff finally starts
ejecting northeast in response to another strong Pacific wave diving
along the California coast.

&&

.LONG TERM /Thursday through Sunday/...
The forecast for later this week and through the weekend is much
less certain as guidance is unsure of the track of a third weather
system. Thursday is likely to be a mostly dry day with only some
lingering light shower chances across eastern Arizona as the second
system will be exiting to the east. However, by Friday and Saturday
rain chances may again spread over the region as yet another fairly
potent Pacific trough tracks southward along the coast of
California. Over the past couple of days, guidance has been trending
toward keeping the low more to our west, potentially far enough to
the west to not bring widespread rain chances. However, it may
eventually swing through our region by around Sunday or Monday.
Forecast PoPs and rainfall amounts for this third event are still
very uncertain and changes are expected. If the low center does
manage to stay completely to our west and south (20-30%
probability), we may not see much additional precipitation, but it
seems more likely it will at some point swing through the Desert
Southwest. We should hopefully have a better idea what will happen
during the middle part of this week.

&&

.AVIATION...Updated at 1800Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
The main aviation concerns will be the presence of VFR CIGs during
much of the period along with periods of VCSH and SHRA that could
result in reduced VIS. Multiple windows of rainfall are expected
with the first most likely occurring between 02-06Z this evening.
The next rounds look to be from 12Z onward but VCSHs through much,
if not the entire night is conceivable. In terms of sub VFR
conditions, the most likely timeframe would be with that second
round of rainfall, but confidence is still too low at this time to
include any prevailing MVFR CIGS or VIS in the TAFs. The most likely
sites to see these sub-optimal conditions would be KSDL and KDVT
where TEMPO groups have been introduced to address these higher
probabilities. Other than perhaps a brief switch to the SSW/SW this
evening associated with the first round of showers, winds should
favor and E/SE component throughout the forecast window.


Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns are expected during the next 24 hours.
S/SE winds at each terminal with eventually switch to the S/SW later
in the period with speeds remaining generally light (aob 10 kts).
VCSH activity cannot be ruled out during the late evening into
overnight timeframe, but confidence is too low to include any
mention of rainfall impacting the terminals at this time. BKN-OVC
skies will be common through Tuesday morning with the lowest bases
around 7-8k ft.

&&

.FIRE WEATHER...
After a brief respite to the active weather pattern during the first
half of today, rain chances will increase later today with wetting
rainfall chances returning by Tuesday morning. Periods of showers
and a few isolated thunderstorms will affect much of the eastern
districts on Tuesday with much more limited activity  across the
western districts. Below normal temperatures and elevated moisture
will remain in place keeping MinRHs between 40-70%, while overnight
recoveries will be good to excellent at 60-100%. Locally gusty winds
upwards of 20 mph will be possible at times, though weaker wind
speeds will be more common through the period. The active weather
with rain chances persisting across the eastern districts should
continue through Wednesday before a brief break is seen on Thursday.
Another weather system may eventually affect the area by the weekend
as temperatures mostly remain below normal and humidities stay
elevated.

&&

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

&&

$$

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