525
FXUS65 KPSR 182303
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
400 PM MST Sat Apr 18 2026

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- High pressure over the Southern Plains will cause breezy to windy
conditions for portions of south-central Arizona Sunday morning,
with the strongest gusts over higher terrain east of Phoenix.

- Temperatures will warm through the beginning of next week,
reaching 5 to 10 degrees above daily normals, which translates to
widespread lower desert highs in the nineties.

- Periods of breezy to locally windy conditions and cooler
temperatures are expected by the middle of next week.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...
It is a crisp sunny start to the weekend across much of the Desert
Southwest with shortwave ridging progressing across the area. The
sunshine and high pressure has already contributed to a 24-hr
surface temperature change of around +4-7F. The warming today will
lead to afternoon high temperatures reaching the lower 90s across
most lower desert communities, which is around 5 degrees above
normal. Winds are much lighter today across SE CA and SW AZ, as the
surface pressure along the Lower Colorado River weakened with the
shifting eastward of the Great Basin surface high. Winds are also
fairly light across south- central AZ following some morning
northeasterly breezes.

A strengthening surface high in the Southern Plains tonight will set
up a strong pressure gradient across parts of southern NM and AZ and
lead to enhanced easterly winds. Comparatively, ensemble guidance is
predicting a weaker gradient than the very strong one that set up
back on March 28th, which saw wind gusts measure up to around 40-45
mph in the high terrain east of Phoenix in the morning, with 25-35
mph measured in the lower deserts of South- Central AZ. The March
28th gradient wind event also produced a lot of lofted dust that
became apparent after sunrise. Similar conditions are a reasonable
expectation with tonight/tomorrow morning`s gradient wind event
although it is expected to be a degree of magnitude weaker than the
March 28th event. Hi-res models and the NBM support localized
mountaintop wind gusts up to 45-50 mph, with up to 35-45 in some
higher terrain communities, like San Carlos and Globe/Miami, while
lower elevations of South-Central AZ can reasonably anticipate up to
25-35 mph gusts after sunrise tomorrow. A Wind Advisory has been
issued for most high terrain areas east of Phoenix from 3 AM - 11 AM
MST tomorrow. Wind gusts should abate through the afternoon as the
gradient relaxes.

As is common with elevated breezes during the overnight and  morning
hours, morning low temperatures will likely be warmer than the NBM
deterministic forecast. As a result, lows were boosted up a few
degrees across south-central AZ and bring record warm low into the
picture for Phoenix (current record: 73F). Afternoon high
temperatures tomorrow are expected to warm another few degrees
compared to today, under continued high pressure and southerly mid-
level flow. Lower desert highs will push into the mid-90s, which is
around 10 degrees above normal for this time of year. There will
also be an increase in high clouds and some high-based cumulus
downstream of a very weak shortwave trough. A few echoes of virga
and a brief light sprinkle shower cannot be ruled tomorrow evening,
with weak mid-level ascent, in parts of south- central and southeast
AZ.

While a pronounced Eastern Pacific cutoff low will near the northern
CA coast Monday, higher pressure and warm southerly flow will
persist across AZ and southeast CA. As a result, temperatures will
again warm into the middle 90s across the lower deserts and the
clouds will clear up as the very weak shortwave departs. Although,
some lingering midlevel moisture may be enough for a few afternoon
convective shower across the eastern AZ high terrain, mainly in the
White Mountain. The easterly gradient wind will be much weaker
tomorrow night into Monday, as the Southern Plains surface high
shifts further east, with no impactful wind gusts expected.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
By the middle of the upcoming work week, the pattern will begin  to
shift. The upper low off the West Coast will push inland over the
Western US, albeit in a weakening phase. Ensembles are in good
agreement on this evolution, but details such as the N/S
displacement of the low and the exact timing/speed of its eastward
progression remain unclear. On a large scale, a broad area of
positive midlevel height anomalies looks to establish off the
Pacific Northwest/British Columbia with negative height anomalies to
its south and east. This is in response to a split jet regime, where
much of the Western and Central CONUS falls under the broad cyclonic
flow of the poorly defined southern stream. As a result, we can
expect cooler temperatures (likely closer to seasonal levels, in the
80s across the lower deserts) Wednesday onward across the forecast
area, and periods of breezy to locally windy conditions as
shortwaves progress through the Desert Southwest. The first period
of increased winds will likely be Tuesday into Wednesday, especially
for the Western CWA, as the initial, broad upper low moves inland
and packs heights fields over the Southwest U.S..

&&

.AVIATION...Updated at 2300Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Gusty winds and uncertainty in timing of wind shifts will be the
main weather forecast issues through Sunday afternoon under
increasing high cirrus decks. Confidence in exact wind directions
through the evening is low as variability mixes with a light
westerly component. Confidence is much better than east winds will
resume overnight with stronger gusts materializing near or after
sunrise. Conditions may flirt with LLWS criteria, as well as
becoming conducive towards importing lofted dust and creating
slantwise vsby issues around sunrise Sunday. After an extended
periods of 20-30kt gusts, speeds should relax mid/late afternoon
with moderate odds of becoming variable or light westerly around
sunset.


Southeast California/Southwest Arizona including KIPL and KBLH:
No major weather issues will exist through Sunday evening under
periods of increasing high cirrus decks. Confidence in wind
forecasts is moderate with a W/NW component favored at KIPL and
varying between NW and S at KBLH. Extended periods of nearly calm
conditions may be common.

&&

.FIRE WEATHER...
Dry and occasionally breezy conditions will prevail through the next
week. Winds will be light today, generally below 15 mph, and then a
strong easterly wind will develop across south-central AZ tomorrow
morning. The strongest winds will be over the higher terrain of the
eastern districts, with wind gusts pushing up to 35-45 mph, but
shortly after sunrise, gusts up to 25-35 mph are likely to become
common across the lower elevations. Given the time of day of
strongest winds, RH values will be above critical levels. Still,
some locally elevated fire weather conditions may exist across south-
 central AZ midday through early afternoon tomorrow. 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 will also vary through the next week, but fall mostly in
the 30-50% range.


&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Wind Advisory from 3 AM to 11 AM MST Sunday for AZZ547-552-555-
     557-558-560>563.

CA...None.

&&

$$

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

NWS PSR Office Area Forecast Discussion