South West Weather

322
FXUS65 KPSR 181717
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1015 AM MST Tue Nov 18 2025

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- A slow moving weather disturbance will continue to bring periodic
rain showers with a few isolated thunderstorms mainly cross southern
and central Arizona through Wednesday night.

- Another weather system should bring rain chances Friday into the
weekend with the main area of focus across southeast California.

- Temperatures this week will hover below the seasonal normal with
readings around 10 degrees below normal Wednesday through Friday.

&&

.SHORT TERM /Today through Wednesday/...
A large Pacific trough continues to slowly drifting southeastward
across California and is now extending into the Desert Southwest.
Ample upper level forcing and low level upslope southwesterly flow
associated with the trough has allowed for occasional showers since
last evening with the best area of focus across southwest Arizona
into Maricopa County. Moisture levels will remain quite high at
between 175-225% of normal today before gradually lowering beginning
Wednesday. The combination of the moisture and the persistent
forcing from the slow moving system will continue to bring periods
of shower activity today and Wednesday across much of Arizona with
some showers likely lingering across eastern Arizona into Thursday.
Guidance is still showing some modest elevated instability for today
which should result in some occasional embedded thunderstorms
producing enhanced rainfall rates.

Forecast rainfall totals are still looking quite good across the
area with the highest amounts focused across central Arizona. The
western lower deserts of southeast California will largely miss out
on the rain with amounts generally less than 0.10". The Arizona
lower deserts should average between 0.50-1.00" with even the higher
amounts likely across northern La Paz and Maricopa Counties. It
would not be surprising to see amounts as high as 1.50-2.00" along
the Maricopa/Yavapai border. Since this event is quite drawn out,
the threat for any flooding issues is rather small. However, we
should at least expect normally dry washes to begin to flow which
could impact some low water crossings.

The already cooler temperatures will drop even further by Wednesday
as the cold core of the system moves into the region. After the
overnight lows in the 50s tonight, we are not expecting much warming
on Wednesday with highs barely topping 60 degrees. Overnight lows
Wednesday night/Thursday morning should easily dip into the 40s
across southeast California and southwest Arizona as much of the
clouds will gradually scatter out.

&&

.LONG TERM /Thursday through Sunday/...
The slow moving trough is expected to be finally pick up speed on
Thursday as it finally exits to the east by later in the afternoon.
Guidance is still showing some lingering showers focused across the
eastern Arizona high terrain for Thursday morning and potentially
into the afternoon, but additional rainfall amounts should fall
short of 0.25". The Phoenix area may also see some lingering light
shower activity through the first part of the morning hours on
Thursday. The exiting system should allow for a decent amount of
sunshine across the area by the afternoon, but the cold air mass
will keep daytime highs in the lower 60s across the Phoenix area to
the mid to upper 60s across far southwest Arizona into southeast
California.

Ensemble guidance is finally starting to have better agreement with
the third weather system which is slated to quickly dive southward
into the back side of the larger scale trough later Thursday into
Friday. Models are now favoring a track which would largely bypass
Arizona on Friday, but it should place southern California into a
prime area of forced ascent and precip development. This should
result in a fairly rainy day on Friday across southeast Califonria
into portions of far southwest Arizona. The latest QPF amounts show
rain totals as high as 0.75" across the western half of Imperial
County and central Riverside County to 0.25-0.5" into the Yuma area.

The low center is likely to keep moving south southeastward to over
the northern Baja area Friday night and Saturday with the most
likely path taking it more toward the east across northern Mexico on
Sunday. If this forecast track holds, it is likely to be far enough
to the south to not bring much rainfall to south-central or eastern
Arizona. That`s not to say those locations won`t see additional rain
over the weekend, but it is likely to be on the lighter side and
more sparse compared to what the western deserts should see on
Friday.

&&

.AVIATION...Updated at 1115Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Periods of SHRA, lower cigs and visibilities, variable wind
directions, and a lower chance for TS will all be weather issue
through Wednesday afternoon. In general, the greatest impacts with
lower cigs, reduced vsby, and wind shifts will occur with
individual rounds of showers. Exact timing of these rounds of SHRA
is low confidence, but most modeling suggest the periods of late
afternoon/early evening, late tonight/early Wednesday morning, then
again Wednesday afternoon. VFR conditions with cigs 040-060 will be
the most likely outcome through tonight, then higher probabilities
of MVFR cigs arrive later Wednesday morning through the afternoon.
Winds will favor a S/SE direction the majority of the period,
however directions become far more uncertain Wednesday afternoon as
a west or north component starts to become more likely.


Southeast California/Southwest Arizona including KIPL and KBLH:
Weather issues through tonight will be scattered SHRA with
occasional lower cigs, restricted visibilities, and variable winds.
Activity should begin clearing SE California this evening with
improving conditions overnight and Wednesday. Winds will favor a
westerly direction at KIPL and southwest veering to northwest at
KBLH. Variability in direction and speed will be common near any
more robust SHRA.

&&

.FIRE WEATHER...
Periodic showers along with a few isolated thunderstorms will affect
much of Arizona through Wednesday providing very good chances for
wetting rains. Below normal temperatures and elevated moisture will
remain in place keeping MinRHs in a 40-70% range following excellent
overnight recovery greater than 80%. Locally gusty winds upwards of
20 mph will be possible at times, though weaker wind speeds will be
more common through the period.  Another weather system is expected
to move across the western districts on Friday leading to additional
wetting rain chances with chances eventually moving over the eastern
districts over the weekend. Temperatures will mostly remain below
normal through the weekend with humidities staying elevated.

&&

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

&&

$$

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