300
FXUS65 KPSR 161019
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
319 AM MST Thu Apr 16 2026

.KEY MESSAGES...

- A weather system passing the region to the north will result in
  widespread breezy conditions by this afternoon followed by
  locally windy conditions and elevated fire weather concerns
  Friday along the Lower Colorado River Valley.

- A Wind Advisory will be in effect from early Friday morning
  into the early afternoon for the Lower Colorado River Valley and
  portions of Southeast California.

- After a brief stint of near and below normal temperatures over
  the next few days, readings will rebound with widespread
  afternoon highs in the 90s expected by the end of the weekend.

&&

.SHORT TERM /TODAY THROUGH FRIDAY/...
Midlevel water vapor imagery early this morning depicts a
shortwave trough progressing over the Pacific Northwest with its
base now rounding the Great Basin. Meanwhile, a much weaker upper
level low off the Northern Baja has formed and begun to draw
closer to the forecast area, sending abundant high clouds towards
the region. The more potent shortwave over the Pacific Northwest
will continue progressing over the intermountain west over the
next 24-36 hours, becoming somewhat more amplified as its southern
extent brushes Northern AZ. Regional pressure gradients will
increase through tonight as a result, leading breezy conditions to
materialize over much of the area later today. However, guidance
has backed off slightly on the magnitude of gusts this afternoon,
perhaps picking up on the influence of the high clouds streaming
over the region, which will inhibit better momentum transfer
towards the surface during the typical peak mixing timeframe.
Thus, expect widespread gusts to between 15-25 mph later today,
with locally higher gusts in the areas typically prone to gap
winds and mountain rotor activity in Western Imperial County.

The strongest winds from this initial shortwave will actually
come Friday, particularly along the Lower Colorado River Valley
and wind prone areas/prominent terrain features in Southeast CA.
As the shortwave progresses E/SE`wrd, it will send a dry front
down the Colorado River Valley. Pressure packing behind the front
will be the impetus to form a nocturnal LLJ, with NAEFS mean 850
mb winds accelerating upwards of 30 kts over a relatively small
area. This is above the 99th percentile of CFSR climatology.
Expect windy conditions to materialize, particularly after
sunrise, with northerly gusts to 30-45 mph becoming common and
locally stronger gusts over ridgelines/terrain features. This will
present difficult driving conditions, especially for high profile
vehicles along the section of I-10 near and west of Blythe, CA,
and some localized channels of blowing dust may be observed. A
Wind Advisory has been issued for Friday, valid 3 AM through 1 PM
MST/PDT for the affected areas.

Temperatures today will be within a few degrees of normal, with
afternoon highs reaching the upper 80s for the typically warmer
lower desert locales. However, the abundant high clouds may cause
highs to underachieve today. NBM highs Friday are slightly warmer
than the past few runs but still 2F-6F cooler than today thanks
to the lower heights aloft and passage of a poorly defined cold
front.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Ensembles advertise the overall pattern stagnating somewhat for a
few days late this weekend into early next week, with upper level
ridging building over the West-Central CONUS and another
relatively potent upper low diving southward from the Gulf of
Alaska and settling off the West Coast. The influence of high
pressure over the region will allow temperatures to rebound over
the weekend, with lower desert highs once again reaching the 90s
and in a decidedly above normal category by Sunday. Something that
is becoming more clear in the global model guidance is that a
strong surface high will shift from the Intermountain West to the
Southern Plains by Sunday, allowing another E/SE`rly gradient wind
event to take shape Sunday morning. This will mostly impact
Southeastern AZ, but likely extend into South-Central AZ higher
terrain east/southeast of Phoenix.

Forecast uncertainty increases considerably heading into the middle
of the upcoming workweek, when the upper low off the West Coast is
expected to move inland over the Great Basin or even over the Desert
Southwest. The uncertainty is reflected in the probabilistic NBM
temperatures, as IQRs for the forecast highs/lows increase to 5F
or greater Tuesday onward. Overall, temperatures should retreat
closer to or even slightly below seasonal normals during the
middle of next week. Another uncertainty is whether the forcing
from the incoming upper low will combine with meager moisture
(mostly in the mid levels) to produce light shower activity over
portions of AZ. However, the vast majority of global guidance
shows the area remaining dry, with PoPs below 10%. From
experience, the track of this low is also not promising to produce
anything more than light precip totals favoring upslope areas and
higher terrain.

&&

.AVIATION...Updated at 0510Z.

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

No significant weather issues will exist through Thursday night
under developing high cirrus cigs. Timing of directional wind shifts
should be similar to the past 24 hours, although west winds will be
maintained around the Phoenix metro longer into Thursday night than
usual. Wind speeds from the mid afternoon through early evening will
be stronger than the past several days with occasional gusts 15-20kt
across the region.

&&

.FIRE WEATHER...
Dry and occasional breezy conditions will prevail through the next
week. Temperatures will cool from near normal today to slightly
below normal Friday, then warm above normal over the weekend. A
weather system passing the region to the north will send a cold
front down the Colorado River Valley and produce gusty winds
Friday morning, with gusts to 30-45 mph for portions of Southeast
CA and Southwest AZ. Winds will gradually relax heading into the
afternoon as humidity drops into the single digits. Elevated and
locally critical fire weather conditions are expected to
materialize for portions of the western deserts Friday as a
result, particularly along the Lower Colorado River Valley.
Afternoon MinRHs below 15% and at times in the single digits will
be common through the next 7 days, with minor day to day
variations. Overnight recoveries between 30-50% tonight will drop
into 15-30% range Friday and Saturday nights.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Wind Advisory from 3 AM to 1 PM MST Friday for AZZ530.

CA...Wind Advisory from 3 AM to 1 PM PDT Friday for CAZ560-561-564-
     565-568>570.

&&

$$

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