225
FXUS65 KPSR 250550
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1050 PM MST Fri May 24 2024

.UPDATE...Updated 06Z Aviation Discussion.

&&

.SYNOPSIS...
A weak area of low pressure will move over the region during the
front half of the weekend, resulting in a quick relative cooldown
and breezy to locally windy conditions. The strongest gusts will be
focused over southeast California this afternoon and evening, with
more widespread breeziness developing again on Saturday. Temperatures
will quickly warm up into the triple digits by the end of the
Memorial Day Weekend, with further warming into the start of the
next work week.

&&

.DISCUSSION...
Atmospheric analysis reveals quasi-zonal flow over our forecast
area, with a weak shortwave trough just west of the California
Coast. Before negative height anomalies associated with this
system move onshore, temperatures today will hover around what we
have seen over the past several days. Afternoon highs will
continue to run in the middle and upper 90s across the lower
deserts, which is right at normal for this time of year. Although
this disturbance is not expected to move over our area until late
tonight/early Saturday morning, its influence will be felt across
portions of the Desert Southwest as early as this
afternoon/evening as breezy to locally windy conditions begin to
develop. The strongest winds will focus over parts of SE
California, where gusts 30-40 mph will be common. HREF guidance
continues to show high probabilities (>80%) of winds exceeding 40
mph over parts of the Imperial Valley, resulting in a Wind
Advisory being posted for this area that will be in effect this
afternoon through the evening hours. Elsewhere across southwestern
and south-central Arizona, peak gusts will generally range
between 20-30 mph, with isolated higher gusts around the Colorado
River Valley and enhanced terrain features.

Once the aforementioned trough moves onshore, regional heights aloft
will decrease as cooler air begins to spread over our forecast area.
Afternoon highs on Saturday, as a result, are forecasted to range
between the upper 80s to lower 90s, a good 5-10 degrees below normal
for this time of year. Enhanced flow aloft will likely yield breezy
conditions across Arizona again on Saturday, with the highest
gusts focused over high-terrain areas. However, the wind forecast
has become a bit murkier since yesterday. The NBM favors gusts
near 30-35 mph over Gila County, while the newest HREF guidance
has gust only reaching near 25 mph over the same areas. This
disagreement appears to stem from some models having the strongest
flow aloft occurring before the hours of peak mixing, limiting
the transfer of the highest momentum winds down to the surface.
Nonetheless, it would not be surprising to see wind gusts range
somewhere in between these two ensemble forecasts, with gusts
ranging between 25-30 mph, with the occasional gust near 35 mph.
Peak gusts of 20-25 mph can be expected across the lower
elevations of south-central and southwestern Arizona. Familiar
terrain-driven winds will push gusts for parts of SE California
towards 30-35 mph once again on Saturday afternoon/evening, but
winds should remain below advisory-levels.

Future guidance remains in excellent agreement regarding a
developing amplified ridging pattern in the wake of the
previously discussed trough. Heights aloft will quickly rise
through the latter portion of the weekend, resulting in a quick
rebound of day-to-day temperatures. Daytime highs by Sunday will
be back in the middle to upper 90s across the lower deserts before
rising further into the triple digits for many areas by Memorial
Day. Projections show the ridge continuing to amplify into the
next work week, leading to further warming. Widespread 100-105
degree temperatures are forecasted by Tuesday, with similar
conditions expected once again on Wednesday. This pattern will
promote tranquil and very dry conditions, yielding near-zero rain
chances for the next several days and likely through the end of
the month, barring any significant changes to ensembles guidance
in the near future.

&&

.AVIATION...Updated at 0550Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

Westerly winds around 10 kt will continue into the overnight hours
before switching to easterly around 10-11Z with speeds aob 8 kt.
Winds will then switch back westerly during the mid-to-late
morning hours. Westerly winds will then gust 15-20 kt during the
afternoon and early evening hours before decoupling after sunset
with speeds lessening to aob 7 kt for the evening and overnight hours.
Clear skies will continue through the TAF period.

Southeast California/Southwest Arizona including KIPL and KBLH:

Winds will remain westerly at KIPL and southwesterly at KBLH
through the TAF period. Wind speeds have started to come down at
both sites. At KIPL winds will gust to around 25 kt through the
overnight hours before picking back up with gusts of 25-30 kt for
the afternoon and evening hours tomorrow. At KBLH winds will gust
around 25 kt over the next couple of hours before lessening to
speeds around 10 kt for the overnight and morning hours tomorrow.
Winds will then gust 15-20 kt during the afternoon and evening
hours tomorrow. Clear skies will continue through the TAF period.

&&

.FIRE WEATHER...
Elevated fire weather conditions will exist today and Saturday over
parts of the western districts and high terrain of the eastern
districts as a weak system helps to generate breezy to locally windy
conditions. Strongest winds (35-45 mph peak gusts) will be focused
over the western districts and enhanced terrain areas, with 20-30
mph gusts expected elsewhere. MinRH values during this timeframe
will increase slightly from 10-15% today, to 10-20% Saturday.
Overnight recoveries will be fair tonight and Saturday night at
around 30-50% and locally higher in high terrain locations. Hot and
dry conditions will persist beyond Saturday, with generally lighter
winds speeds and typical afternoon breeziness each day. Daily highs
will reach the century mark in many lower desert locations by Monday
and values generally top out between 100-105 through the middle
of next week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 9 AM PDT Saturday for CAZ562.

     Wind Advisory until 11 PM PDT this evening for CAZ563-566-567.

&&

$$

DISCUSSION...RW
AVIATION...Berislavich
FIRE WEATHER...Whittock/RW