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000
FXUS65 KPSR 232355
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
455 PM MST Tue Apr 23 2024

.UPDATE...Updated 00Z Aviation Discussion.

&&

.SYNOPSIS...
A couple of weather systems will move through the region in the
Wednesday through Saturday time frame. This will lead to a
significant cooling trend as well as breezy to windy conditions.
Desert highs drop to the lower 80s Friday and Saturday. Moisture
with these systems will be quite limited and thus precipitation
chances will be confined primarily to the northern half of
Arizona. An exception will be slight chances of showers for east-
central Arizona and far northern Maricopa County on Friday night
and Saturday morning. A warming trend begins Sunday with desert highs
returning to the 90s Monday and Tuesday.

&&

.DISCUSSION...

Model trends remain on track with an upper low off the California
coast moving through Wed-Thu and a follow-on shortwave from the
Pacific Northwest moving through Fri-Sat. Despite dynamical
forcing and cooling aloft with those systems, moisture looks to be
limited and thus PoPs are quite meager. The NBM 90th percentile
12 hour QPF is zero over our forecast area until Friday night and
Saturday. Even then, the amounts are less than one tenth of an
inch and only cover portions of south-central AZ. Something to
keep an eye on however is that some of the CAMS (e.g. NamNest and
to a lesser extent FV3) are depicting a batch of showers moving
through southwest AZ and western Maricopa County on Wednesday
night/early Thursday. This is plausible given the aforementioned
lifting mechanisms but not enough to go on yet to introduce
mention of precip for those areas during that time.

The most noticeable sensible weather impacts from the passage of
these systems will be the cooling trend and breezy to windy
conditions. Highs on the lower elevations drop to the lower 80s
by Friday and Saturday (upper 70s some spots). A warming trend
follows with highs getting pretty close to the peaks we`ve just
had by next Tuesday. As for winds, Wednesday through Friday look
to be the windiest with less windy, though still breezy,
conditions Saturday. Advisory strength conditions (gusts 40+ mph)
are expected to be limited to our portion of southeast California
(mainly Imperial County). A Wind Advisory has been issued for the
southwest corner of Imperial County from 5pm Wednesday to 11pm
Friday. There is also a Wind Advisory for much of the rest of
Imperial County for a shorter period of time (5pm Wednesday to 3am
Thursday). Likewise for western portions of Joshua Tree N.P. It`s
possible that another Advisory for those areas may be needed for
later Thursday.

&&

.AVIATION...Updated at 2355Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Winds are still slowly making their turn to westerly and
directions will continue to be 140v210 with gusts of 15-20 kt
until 01-02Z when winds become westerly. Westerly winds will gusts
15-20 kt will continue until mid-to-late this evening when wind
speeds will calm down and then become easterly for the overnight
hours. Winds tomorrow will follow a similar pattern as they did
today. By mid-morning winds will start to slowly make their turn
to westerly with directions of 140v210 expected again with gusts
of 15-20 kt during the afternoon. FEW-SCT high clouds are expected
throughout the day tomorrow.

Southeast California/Southwest Arizona including KIPL and KBLH:
Winds at KIPL will mainly be out of the west whereas at KBLH winds
will mainly be out of the S/SW through the TAF period. Wind gusts
of 15-20 kt will continue through the mid-evening at KBLH and
through the late-evening at KIPL. Winds speeds will decrease at
both terminals for the overnight and morning hours before starting
to pick up speed again for the mid-to-late afternoon hours. Skies
will be mostly clear with FEW high clouds expected tomorrow
morning.

&&

.FIRE WEATHER...
A couple of weather systems will move through the region in the
Wednesday through Saturday time frame. This will lead to a
significant cooling trend as well as breezy to windy conditions.
Conditions will flirt with critical wind and humidity thresholds
for a few hours late Wednesday afternoon in some spots near and
west of the Lower Colorado River Valley. Otherwise, increasing
humidities will preclude critical fire weather conditions. For
instance MinRH values on Wednesday will be in the 10-15% range
across much of the forecast area followed by an increase of 5-10%
on Thursday with little change on Friday. However, these systems
will struggle to produce precipitation over the forecast area with
rain chances confined to the northern half of Arizona. An
exception will be slight chances of showers for higher terrain and
foothill locations of south-central AZ on Friday night and
Saturday morning. A warming trend begins Sunday with desert highs
returning to the mid and upper 90s by Tuesday. MinRH values drop
to the 10-20% range by Sunday and 10-15% range by Monday. MaxRH
bottoms out in the 25-50% range Tuesday morning.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory from 5 PM Wednesday to 3 AM PDT Thursday for
     CAZ560-563-565>567.

     Wind Advisory from 5 PM Wednesday to midnight PDT Friday night
     for CAZ562.

&&

$$

DISCUSSION...AJ
AVIATION...Berislavich
FIRE WEATHER...AJ