390
FXUS65 KPSR 151013
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
313 AM MST Sat Nov 15 2025

.KEY MESSAGES...

- The first in a series of three weather systems will affect the
  region this weekend bringing fairly widespread light to moderate
  rainfall but little impacts.

- Temperatures are expected to cool well below normal starting
  Sunday and last through all of next week.

- A second weather system with rain more focused across Arizona is
  expected for Tuesday.

&&

.SHORT TERM /TODAY THROUGH SUNDAY/...
A deep Pacific low pressure system is currently centered just west
of San Diego with strong southerly moisture advection and
rainfall impacting the coast of California. The slow progression
of the system has directed the bulk of the moisture and energy
into southern and central California with rain-shadowing keeping
most of the rain from getting over the interior mountains. For
today, the trough is set to slowly drift more to the east
allowing for better forcing and moisture to finally move into
southeast California and eventually into Arizona tonight into
Sunday.

Model guidance continues to lower expected rainfall amounts for
much of the area this weekend, especially across Arizona. Rain
should peak across southeast California later this morning and
through the afternoon hours with more scattered shower/embedded
thunderstorm activity eventually swinging through southern and
central Arizona Saturday night/Sunday morning. QPF amounts have
been lowered to show an average of 0.25-0.5" across the southeast
California lower deserts to 0.1-0.25" for the Arizona lower
deserts. Some lower desert areas may end up seeing between 0.5-1",
but that should be very localized. Higher rainfall totals are
still expected across JTNP where upwards of an inch is likely to
fall through this evening. Forecast totals for the Arizona higher
terrain have also fallen to between 0.25-0.5", with slightly
higher totals over ridgetop locations.

Temperatures today are still expected to be fairly warm across the
Arizona lower deserts with highs likely topping 80 degrees. More
cloud cover and the rainfall across the western deserts should
keep daytime highs today between 70-75 degrees. Once the cold
front pushes through the entire area by later Sunday morning, the
below normal temperatures will finally be seen.

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
After this weekend`s weather system weakens and finally exits to
the northeast by Sunday night, a second shortwave will be
following behind within the broader trough which will remain in
place across the Western U.S. Guidance is now showing better
agreement with the progression with this second system with a
closed low first developing across California on Monday before
tracking south southeastward into our region on Tuesday. There is
still some slight timing and position differences within the
ensemble members, so that in turn means there is uncertainty with
the rainfall totals and exactly when the peak rain will occur.
Some showers may begin to develop late Monday and Monday night,
especially across higher terrain areas before more widespread rain
is likely to occur on Tuesday. This system should bring better
dynamics and forcing than the first, potentially allowing for a
more organized rain event. Forecast moisture levels will be lower
than this weekend`s system, but given the Tuesday system will be
colder that should compensate for the lower available moisture.
Potential rainfall amounts are still fairly uncertain, but the
higher end of potential shows upwards of an inch possible across
south-central Arizona to 0.25-0.5" across the southeast California
lower deserts. As of right now, we are going with a more
conservative 0.1-0.25" for SE CA and around 0.5" for the south-
central Arizona lower deserts. Higher terrain areas north and east
of Phoenix may end up getting another 0.75-1.25" by the time the
rain ends either Tuesday night or early Wednesday.

The active weather period is expected to continue through the rest
of next week with a third somewhat cold system quickly moving
from off the Pacific Northwest on Thursday into our region around
Friday or Saturday. Model uncertainty is even higher with this
third system, but it could end up being the best precip maker.
There are around 30% of the ensemble members that show a more
progressive system which would not provide much additional
precipitation, but another 30-50% show a much slower closed off
low which may stick around for a couple of days.

Temperatures next week will be fairly chilly all week with highs
mostly staying below 70 degrees each day. As of right now,
Wednesday may end up being the coldest day with highs only in the
lower 60s for some lower deserts locations. The persistent higher
boundary layer moisture and clouds should at least keep overnight
lows fairly close to normal readings most nights.

&&

.AVIATION...Updated at 0550Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
The main concerns during the TAF period will be the introduction
of VFR CIGs between 6-8 kft AGL Saturday afternoon, increasing
chances for VCSH/SHRA conditions Saturday evening, and lower than
usual confidence on wind directions because of the approaching
shower activity. This is the result of a slow moving weather
system currently affecting parts of SoCal that will eventually
pass just north of the PHX airspace on Sunday. Until Saturday
afternoon, anticipate winds to remain light (generally AOB 6 kts)
and follow typical diurnal trends. Winds will begin to favor S/SE
late Saturday morning and slowly veer out of the SW during the
afternoon.

Saturday evening through Sunday morning, chances for -RA/RA will
increase to between 50-80% at the terminals, and a few embedded,
weak thunderstorms cannot be ruled out (15-20% chances). CIGs are
also likely to drop into a 4-6 kft AGL range during this time,
with scattered lower decks possible. Chances for temporary MVFR
visibilities during RA are around 20%, with similar chances for
brief MVFR CIGs Sunday morning.

Southeast California/Southwest Arizona including KIPL and KBLH:
The main aviation concern during the next 24 hours remains the
potential for showers resulting in low CIGs and reduced VIS. These
concerns will be focused over KIPL at first, where shower activity
will increase through Saturday morning. Chances for MVFR CIGs have
increased to around 30-35%, and so have included this in a tempo
group during the late morning into the early afternoon. As for
KBLH, chances for -SHRA peak during the afternoon, but chances for
MVFR CIGs are too low (15%) to warrant inclusion in the TAF.
However, Hi-Res guidance indicates that rainfall rates may be
higher in the afternoon (at KBLH), likely due to a few embedded
thunderstorms, which could lead to temporary MVFR VIS. Regardless,
lower CIGs and SHRA activity will move out of the area by Saturday
evening, and winds are expected to settle out of the SW.

&&

.FIRE WEATHER...
A large weather system will slowly move through the region
this weekend bringing cooler temperatures, increased humidities,
and fairly widespread rainfall. Rain chances will peak across the
western districts during the daytime hours today and during the
first half of Sunday for the eastern districts. A few isolated
thunderstorms will be possible, which may produce locally heavier
rainfall amounts. MinRHs today will range from 25-30% over the
eastern districts to 50-70% for the western districts. Sunday will
bring MinRHs of 40-60% areawide. Expect periodic breeziness over
the weekend. The active weather will continue through next
week with another weather system affecting the area by Tuesday and
another later in the week. Expect below normal temperatures and
elevated humidities for all of next week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Flood Watch from 4 AM PST Saturday through Saturday evening for
     CAZ560-568.

&&

$$

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