357
FXUS65 KPSR 180908
AFDPSR

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

.KEY MESSAGES...

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

- Yet 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 0545Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
The main aviation concerns over the next 24-36 hrs will be the
presence of BKN to OVC 4-6 kft cloud decks, periods of VCSH and
SHRA that could result in reduced vsby, and a low chance (10-20%)
of TS at all metro terminals. Multiple windows of rainfall are
expected through Tuesday night. The next round looks to arrive
Tuesday morning and persist into the early afternoon. If any MVFR
cigs develop, the most likely timeframe would be around 15Z-18Z,
but confidence is still too low at this time to include mention in
the TAFs. Winds should favor a E/SE component throughout the
forecast window becoming elevated with gusts reaching 18-20 kts
Tuesday afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH:
The main aviation concerns through the forecast period will be
periods of VCSH and SHRA that could result in reduced vsby and
gusty westerly winds that are expected to materialize at KIPL
Tuesday morning. Winds should remain mostly light and vrb
overnight at both terminals before increasing out of the WSW at
KIPL after sunrise Tuesday morning. VCSH will likely develop
across SE California overnight and persist through much of the
period. The best time frame to see heavier bands of SHRA will be
around 14Z-18Z at KIPL and 18Z-21Z at KBLH. BKN-OVC skies will be
common through Tuesday with the lowest bases around 6-8 kft.

&&

.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...RW/Salerno
FIRE WEATHER...Kuhlman