374
FXUS65 KPSR 282208
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
308 PM MST Fri Mar 28 2025

.SYNOPSIS...
Seasonal temperatures, dry conditions, and daily breeziness are
expected through at least early next week. Lower desert high
temperatures will hover in the low to mid eighties. A pattern
shift toward the middle and second half of next week will have the
potential to bring below normal temperatures, a shot at some
rain, and more breezy to windy conditions.

&&

.DISCUSSION...
A shortwave trough is seen very clearly on midlevel WV satellite
this afternoon, moving through the region. This shortwave has
helped cool temperatures back down a little closer to normal and
brought some thicker high clouds and some high level virga that
has been visible as weak echoes on radar. This shortwave has also
led to a tightening of the pressure gradient and breezy to locally
windy conditions. The strongest winds have been across Imperial
County CA over the past 12 hours, with the influences of
downsloping and possible mountain rotors. Wind Gusts in the
Imperial Valley have reached up to 30-40 mph and the southwest
corner of the county has reached 50-55 mph, where a Wind Advisory
remains in effect. Imperial County will remain the breeziest spot.
Lighter breeziness is expected elsewhere, with the lower deserts
mostly around 20-25 mph gusts to 25-35 mph in the higher terrain
north and east of Phoenix. This does look like it will be a daily
occurrence through this weekend, and possibly through all of next
week, as the Southwest will be under a quasi-zonal flow regime
with a couple more shortwave troughs passing quickly by through
this weekend. This regime will also keep temperatures close to
seasonal levels, through at least early next week, with afternoon
highs in the low to mid 80s for the lower deserts.

There still remains a high degree of uncertainty in the weather
forecast from Wednesday through the end of next week, at least as
far as the specific sensible weather impacts (i.e. temperatures,
wind magnitudes, and rain chances). There is good confidence in a
weather pattern shift going into next week, favoring a more
amplified pattern across the Western CONUS as a result of an
upstream blocking pattern developing in the central Pacific.
Global ensembles support increased negative height anomalies
across the Western CONUS beginning around Wednesday, with around
50% of members maintaining negative height anomalies through next
weekend. The main uncertainty will be the depth of longer wave
troughs across the West, timing of troughs, and how progressive or
slow-moving they may be. A lot of the variance in the grand
ensemble is still being driven by a split in solutions between the
less amplified GEFS membership and higher amplified/deeper trough
ENS & GEPS memberships. With the latest 12Z ensembles, the GEFS
mean 500mb heights over AZ has made a slight shift toward the
lower heights/deeper solutions. Deeper solutions will offer
better rain chances, cooler temperatures, and breezier winds. It
is still a too early to talk specifics on rain potential, with any
confidence, for the lower deserts, but latest NBM forecast has
light PoPs (less than 20%) beginning as early as Wednesday.
Friday still looks like the better time period for rain chances
and this is reflected in the PoP forecast, with closer to 20-30%.
Inevitably a strong trough would bring stronger winds to the
region and latest global models are pointing to the Wednesday
timeframe for the breeziest conditions. As for temperatures later
next week, the IQR of the NBM has narrowed a little bit (a delta
of around 10 degrees), with the lower desert high temperature
range around low-70s to low-80s. Solace can at least be taken in
that the next shot at 90 degree temperatures may not come until
closer to middle-April...if you are not a fan of 90+ degrees that
is.

&&

.AVIATION...Updated at 1806Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation weather concerns are expected through the TAF
period under periods of mid and high level CIGs mostly aoa 15 kft.
Light and variable winds will continue to take on a westerly
component going into this afternoon with speeds increasing. May
see some gusts to around 20 kts at times through the afternoon,
but should be more limited with the thicker cloud cover in place.
Expect virga to persist throughout the afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH:
Strong westerly winds at KIPL will be the primary aviation weather
concern through the TAF period. Strong gusts around 25-30 kts at
KIPL will persist through the evening into the overnight period
with a few gusts upwards of 30-35 kts possible through this
evening. At KBLH, speeds will be lighter, with S-SW gusts to
around 20 kts this afternoon into the evening. Mid and high level
CIGs generally aoa 15 kft will persist throughout the period.

&&

.FIRE WEATHER...
Continued dry and breezy conditions are expected to persist
through this weekend, resulting in periods of marginally elevated
fire weather. The strongest winds up to 25-35 mph will reside
across the western districts and higher terrain of Maricopa and
Gila Counties. Minimum relative humidity is expected to range from
15-20% each afternoon and overnight recoveries should remain fair
up to 40-50%. There will be a slow improvement in moisture levels
by the middle to latter portions of next week as a potential
stronger weather system arrives. There is still a lot of
uncertainty whether any meaningful precipitation will accompany
this system, but chances for any wetting rainfall looks very low
at this time.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 5 AM PDT Saturday for CAZ562.

&&

$$

DISCUSSION...Benedict
AVIATION...Smith
FIRE WEATHER...Salerno