885
FXUS65 KPSR 182009
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
109 PM MST Fri Apr 18 2025

.SYNOPSIS...
A weather disturbance will track through the region through early
Saturday bringing breezy to locally windy conditions and
scattered showers and a few thunderstorms across south-central AZ
this evening and tonight. Below normal temperatures will persist
through Saturday before temperatures warm to near normal on Sunday
and slightly above normal heading into next week as weak high
pressure builds over the region.

&&

.DISCUSSION...
Latest water vapor satellite imagery shows an upper low spinning
over Utah with this feature expected to dive southward into northern
AZ by this evening. As this upper low continues to sag southward, a
surface cold front will also move southward as well reaching central
AZ late this afternoon through this evening. Along this front, a
line of showers is expected to break out and affect most of south-
central AZ heading into this evening. Activity, however, should be
short-lived and thus only light rainfall amounts are expected
ranging between a few hundredths of an inch across the Phoenix
area, 0.1-0.2" across the foothills, and 0.15-0.30" across the higher
terrain areas to the north and east of Phoenix. A few thunderstorms
cannot be ruled out with these showers as they move across given
that there will be 50-100 J/KG of CAPE available based on the
latest HREF. There will also be a gusty wind threat associated
with these showers with the 12z HREF indicating about a 30-50% of
wind gusts of 35+ mph this evening. Most of the shower activity
should end across the Phoenix metro around midnight and across
the higher terrain areas east of Phoenix by around sunrise.
Temperatures today with the negative height anomalies from the
approaching trough will continue to be below normal with afternoon
highs in the middle to upper 70s across the lower deserts.

As the main troughing feature pushes eastward into New Mexico on
Saturday, increasing subsidence and much drier air will push into
the region with mostly clear skies prevailing. Lingering negative
height anomalies from the departing trough will continue to
result in below normal temperatures once again for Saturday as
highs are expected to top out in the upper 70s to lower 80s across
the lower deserts. Starting on Sunday and continuing through most
of next week, a quasi-zonal flow pattern will dominate much of
Desert Southwest, resulting in quiet and tranquil conditions.
Temperatures on Sunday will warm back up to near seasonal levels,
in the middle to upper 80s and then warm to slightly above normal
levels heading into next week as highs top out in the upper 80s to
lower 90s. By late next week into the following weekend, global
models show another trough impinging on the west coast. However,
after examining the ensemble clusters, there is a good deal of
spread in the overall positioning and depth of the trough as it
moves into the western CONUS and thus the temperature spread
begins to increase during this period with readings anywhere from
slightly below normal to slightly above normal.

&&

.AVIATION...Updated at 1720Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Breezy to occasionally windy conditions along with periods of
rainfall will be the main aviation concerns during the TAF period.
W`rly winds will prevail through the afternoon and evening, with
occasional gusts to around 20 kts. By the early evening, a broken
line of showers is projected to move through the metro, which
could lead to brief periods of reduced visibilities and gusts
potentially reaching (50% chance) upwards of 30 kts. These showers
should quickly move out by early tonight while wind speeds relax
and switch to the E during much of the overnight. Even with shower
activity, VFR conditions are expected to prevail, with CIGs
remaining AOA 6k ft. However, brief moments of MVFR VIS cannot be
completely ruled out with heavier showers.

Southeast California/Southwest Arizona including KIPL and KBLH:
Breezy to occasionally windy conditions, especially at IPL will be
the main aviation concern over the next 24 hours. Winds are
expected to contain a W`rly component through most of the period,
with gusts at IPL reaching 25-30 kts this afternoon before speeds
relax tonight. At BLH, gusts closer to 20 kts will be common
during the afternoon. Other than a relatively brief window of
lower-clouds (bases 7-9k ft) moving through this afternoon and
evening, skies will be generally clear otherwise.

&&

.FIRE WEATHER...
A weather system will move through the region through early
Saturday will bring more breezy to locally windy conditions and
chances for rain. Expect scattered showers and a few thunderstorms
mainly this evening across south-central Arizona with activity
lingering through the overnight hours across the eastern Arizona
higher terrain. Increased moisture and below normal temperatures
will keep RHs elevated today with MinRHs between 25-35% before
falling back to around 10% by Sunday. Lighter winds are
anticipated starting Saturday while temperatures gradually rise
back to around normal on Sunday. Tranquil weather conditions are
expected for next week with temperatures at or slightly above
normal, seasonably dry conditions, and relatively light winds.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 8 PM PDT this evening for CAZ562.

&&

$$


DISCUSSION...Lojero
AVIATION...RW
FIRE WEATHER...Kuhlman