Area Forecast Discussion
Issued by NWS Phoenix, AZ

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FXUS65 KPSR 221039
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
339 AM MST Fri Mar 22 2024

.SYNOPSIS...
Seasonally warm temperatures will continue today and tomorrow,
before a cooling trend back to well below normal late this weekend
and extending into early next week. A potent weather system will
bring widespread windy conditions across the region beginning
Saturday and lasting through Sunday, with rain chances increasing
across southcentral AZ Sunday into Monday. A return to calmer
conditions expected for the middle of next week.

&&

.DISCUSSION...
The upper level pattern has become more progressive, with the
latest satellite depicting mostly clear skies across the region
this morning. Far off to the northwest, the next system that will
impact the region over the weekend is lurking off the West Coast,
with the frontal band beginning to impacts portions of the
Pacific Northwest. Transient ridging is in place across the region
for today, but will be quickly sliding eastward as the
aforementioned troughing feature will begin impacting the region
tomorrow. For today, the only noteworthy aspect of the sensible
weather will be the temperatures, where we could see the warmest
day of the calendar year across the region (the warmest day for
Phoenix thus far is 84 degrees on February 25th; forecast high
today is 86 degrees). Thus, Minor HeatRisk will continue to linger
across the lower deserts.

Temperatures will begin to cool tomorrow, as the closed low digs
across the West Coast over the next 24 hours. Strong west to
southwest flow between the 850-700 mb levels will develop
tomorrow morning, resulting in windy conditions for a large
portion of SE California for Saturday and lasting into Sunday.
Wind Advisories are in effect for most of Imperial County and
Joshua Tree NP, as winds are expected to gust in excess of 40 mph.
The lower deserts are projected to gust in the 40-50 mph range,
while higher terrain areas, particularly in SW Imperial County,
winds are expected to gust to at least 55 mph, with isolated areas
60+ mph. The peak of the winds are expected to be tomorrow
afternoon/evening, with slightly weaker winds for Sunday
afternoon/evening. Breezy to windy conditions could also spread
further east during the evening hours across Yuma and La Paz
Counties, but gusts exceeding 40 mph is more marginal, thus no
advisories are in effect for those areas at this time (NBM
probabilities of 40+ mph gusts are around 30-50%). Along with
these strong winds, areas of blowing dust may become a factor at
times during the peak wind gusts. Temperatures for Sunday will
dip well below normal, with lower desert highs struggling to reach
70 degrees (50-70% chance temperatures stay below 70 degrees for
Phoenix).

While the winds will be the biggest impact with this system, rain
chances continue to be advertised for southcentral Arizona. Latest
ensemble guidance is more optimistic with rain chances for this
general region, as PWAT`s are expected to increase into the 0.60"
range. Best chances remain in the higher elevations, as the latest
NBM PoP`s are around 20-30% across Phoenix and 50-60% for the
higher terrain north and east of Phoenix Sunday. Due to a slightly
more amplification of the trough advertised by the ensembles, the
latest noticeable change in the outlook going into early next
week is lingering rain potential, mostly confined to the higher
terrain areas, through even Tuesday (NBM PoP`s during the daytime
hours Tuesday is 20-40%). Expectations for storm total rainfall
amounts Sunday through Tuesday are between 0.05-0.25" for the
lower deserts and 0.25-0.50" for the higher terrain areas.

Once the main troughing feature slides east of the region by
Wednesday, heights will likely build, but there still remains
differences amongst the ensembles on how amplified the pattern
will become through the rest of next week. Residual shortwave
action from the exiting trough could keep cooler conditions
continuing into the latter portions of the week (~20% of the
members), while advancing into Thursday, the next longwave digging
into the Pacific Northwest could keep progressive flow across the
region. Regardless, temperatures should warm by at least a few
degrees with the region remaining mostly dry, with a bump in wind
speeds with any shortwaves that dig across the region.

&&

.AVIATION...Updated at 0530Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation weather concerns are anticipated through the TAF
period under mostly clear skies overnight. Winds have calmed this
evening and either gone VRB or begun to switch to their typical
E`rly drainage directions. Wind speeds will remain light,
generally aob 8 kt sustained, through the period. High clouds
(mainly aoa 20 kft) will begin to build in tomorrow morning,
becoming SCT to at times BKN by tomorrow afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns are anticipated through the TAF
period under increasing high clouds. Winds will remain light, with
speeds mainly aob 10 kts sustained, though gusts into the mid-to-
upper teens are expected tomorrow afternoon at KBLH and tomorrow
evening at KIPL. Directions will generally favor S to SW at KBLH
and SW to W at KIPL. High clouds aoa 20 kft will begin to build
over the region by early tomorrow morning, becoming SCT to at
times BKN by late morning.

&&

.FIRE WEATHER...
Dry and tranquil conditions expected through today. Above normal
temperatures today will cool to well below normal by late
weekend. Windy conditions will develop tomorrow and last through
Sunday, with areas across the western districts gusting in excess
of 40 mph (up to 55 mph in higher terrain areas). MinRH values
through tomorrow will generally hover around 15-20% for the lower
deserts and 25-35% for the higher terrain of south-central
Arizona before moistening above 25% for the lower deserts ahead
of the next rain chances Sunday into Monday. Wetting rain chances
are highest in the higher terrain areas of southcentral AZ Sunday
into Monday around 30-50%, while lower desert chances area
marginal around 10-25%. Generally drier and warming conditions
expected going through early next week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory from 8 AM Saturday to 6 AM PDT Monday for CAZ560-
     562>567.

&&

$$

DISCUSSION...Young
AVIATION...Whittock
FIRE WEATHER...Young


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