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000
FXUS65 KPSR 251828
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1128 AM MST Thu Apr 25 2024

.UPDATE...Updated Aviation Discussion.

&&

.SYNOPSIS...
Multiple areas of low pressure will traverse the Desert
Southwest over the next several days, resulting in cooler-than-
normal temperatures through at least Saturday. These systems will
help generate persistent breezy to locally windy conditions while
increasing rainfall potential for some areas. We quickly warm back
up to start next wee as high pressure build over the region.

&&

.DISCUSSION...
The ridge that parked over the region during the past several days
has now pushed off toward the Central Plains while a weak area of
low pressure advances off the eastern Pacific. This trough will
quickly move over our forecast during the next 24 hours, providing
us with much cooler temperatures, continued breezy to locally windy
conditions, and even chances of rain for southwestern Arizona.
Afternoon highs today will be 15-20 degrees cooler compared to where
we were to start the week, with readings only expected to reach into
the lower and middle 80s across the lower deserts. Areas of
southeast California will once again see enhanced winds with peak
gusts around 30-35 mph this afternoon, though a few advisory-level
gusts (40+ mph) are likely again (60-80%) across the Imperial Valley
and areas around the Salton Sea. Although coverage of these enhanced
gusts will be more limited to what was seen yesterday, a Wind
Advisory has been posted for these areas for this afternoon and
evening regardless in addition to the Advisory that remains in
effect for southwestern Imperial County through early Saturday.

Even with relatively limited moisture flux over the region
associated with this trough, showers, with some even containing some
lightning, have been observed over parts of southwestern Arizona
early this morning, which was hinted at by the CAMs over the last
day. Hi- res guidance shows these showers persisting as far as the
late morning hours, mainly across La Paz County, but a light shower
or two over northern Yuma and western Maricopa Counties would not be
surprising. Any totals with these showers will be light, amounting
to generally less than .10".

This initial system will quickly eject out of the region by late
today into early Friday, but a trailing more potent low will file in
behind it, helping to keep conditions cooler and unsettled through
the end of the week. Temperatures Friday afternoon are forecasted to
be, once again, in the lower to middle 80s across the lower deserts,
a good 5 degrees or so below normal for this time of year. Recent
model runs have become more consistent regarding the timing of this
system, with the base of the trough pushing over the region by
Friday afternoon and evening. This timing favors the generation of
more breezy to locally windy conditions this afternoon, but with
this disturbance being deeper than its predecessor, gusts will be
stronger and more widespread compared to today. Gusts greater
than 40 mph are likely (>90% chance) to return across parts of
southeastern California, which has prompted the issuance of
another Wind Advisory for much of Imperial County and the area
around Joshua Tree NP. However, advisory-level winds will not be
limited to those areas alone, as there is high confidence in
seeing similar gusts across portions of the south- central Arizona
high terrain, resulting in a Wind Advisory being posted for parts
of eastern Maricopa and Pinal Counties, as well as southern Gila
County. Winds elsewhere should remain below the advisory
threshold, but gusts between 25-35 mph will be common across the
remainder of the region. These enhanced winds will be capable of
producing areas of blowing dust, especially out in Imperial
County, leading to potentially hazardous travel conditions at
times due to reduced visibilities.

With better kinematic forcing and moisture flux associated with this
secondary system, rain chances continue to be shown for parts of our
forecast areas for late Friday into early Saturday, with the best
chances (30-40%) over northern Maricopa and southern Gila Counties.
Elsewhere across the lower deserts of Maricopa and Pinal Counties,
rain chances have dropped slightly, but PoPs around 10-20% remain.
Rainfall amounts with this round of potential rainfall would again
be on the light side, ranging from 0.01"-0.10", with those higher
totals favored over high terrain areas.

One more day of unseasonably cool conditions, with some residual
breeziness, will occur on Saturday as the aforementioned system
begins ejecting out of the region. Forecasted conditions across the
lower deserts Saturday call for highs in the low to middle 80s, with
widespread gusts between 20-30 mph. From there, after the trough has
fully cleared the Desert Southwest, high pressure will begin to fill
in, leading temperatures on a warming trend as we head into the
start of next week. Temperatures will quickly rise to the middle and
upper 80s for much of the region by Sunday before rising further
into the lower 90s by Monday and then into the mid and upper 90s by
Tuesday.

&&

.AVIATION...Updated at 1828Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Breezy W-SW winds will prevail through the afternoon with gusts up
to 20-25 kts. Winds then subside this evening around 3Z and return
easterly by by 10Z. An early southerly wind will develop Friday
morning, by 15-16Z, and winds will become gusty by late morning,
with peak afternoon gusts Friday around 25-30 kts. FEW to SCT
cumulus around 9-10K ft are anticipated this afternoon and Friday
afternoon. Convective showers and storms will develop and stay
north of the metro area through this afternoon. Another round of
convection is expected to pass to the north Friday afternoon, but
chances of activity clipping into parts of the metro is a little
higher Friday (10-20%).

Southeast California/Southwest Arizona including KIPL and KBLH:
Breezy to windy conditions will continue over the next 24 hours,
with some reprieve tonight through Friday morning. Strongest
westerly wind gusts at KIPL will be this evening, peaking around
30-35 kts. KBLH will see peak southwesterly wind gusts around 25
kts this afternoon and evening. Skies will remain mostly clear
through the period.

&&

.FIRE WEATHER...
Multiple areas of low pressure will traverse the region over the
next several day, helping to cool temperatures and producing daily
occurrences of breezy to locally windy conditions. However, due to
the cooler-than-normal temperatures and rising RH levels, fire
danger will remain limited through the start of this weekend.
MinRH values will range between 20-30%, with good to excellent
overnight recoveries expected. Increasing moisture levels will
also yield chances (~30%) for wetting rain across the high
terrain of the eastern districts late Friday into early Saturday.
Dry and hot conditions return by the start of next week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Wind Advisory from 2 PM Friday to midnight MST Friday night for
     AZZ557-558.

CA...Wind Advisory from 2 PM Friday to midnight PDT Friday night for
     CAZ560-563-565>567.

     Wind Advisory until midnight PDT Friday night for CAZ562.

     Wind Advisory from 3 PM this afternoon to midnight PDT tonight
     for CAZ563-566-567.

&&

$$

DISCUSSION...RW
AVIATION...Benedict
FIRE WEATHER...RW