491
FXUS65 KPSR 110523
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1023 PM MST Thu Apr 10 2025

.UPDATE...Updated Aviation Discussion.

&&

.SYNOPSIS...
Unseasonably hot temperatures will persist across the
region through Saturday as strong high pressure prevails with many
of the lower desert locations likely to reach the triple digits
for afternoon highs. As a weather system passes well to our north,
winds will increase this weekend leading to elevated to locally
critical fire weather conditions. Cooler temperatures, but still
remaining above normal, can be expected late this weekend through
next week.

&&

.DISCUSSION...
The latest RAP analysis shows a strong ridge of high pressure
enveloped across the Desert Southwest with 500 mb height fields
exceeding 588dm. As a result, unseasonably hot temperatures that
are a good 15 degrees above normal will prevail through Saturday.
Many of the lower desert locations are likely to reach or even
exceed 100 degrees, with Friday being the peak in the
temperatures. Temperatures of this magnitude will likely
tie/exceed record highs at all of the three major climate sites
(Phoenix, Yuma, El Centro). Given these anomalously hot
temperatures in place through the next couple of days, the overall
HeatRisk will be in the moderate category. Therefore, for those
partaking in outdoor activities, the necessary heat safety
measures should be taken.

As we head towards the weekend, a shortwave trough passing
through the Pacific Northwest and northern Rockies will cause the
ridge to shift east, lowering the heights aloft and promote a
cooling trend starting on Sunday as high temperatures fall back
into the lower to middle 90s. In addition to the cooling
temperatures, the shortwave trough will create enough of a
pressure gradient to result in enhanced breeziness both Saturday
and Sunday with peak afternoon gusts of 20 to 30 mph across most
of the region, with locally higher gusts in excess of 30 mph
across the higher terrain areas east of Phoenix. The combination
of the elevated winds and very dry conditions will result in
elevated to locally critical fire conditions. As a result, in
coordination with the Tucson office, a fire weather watch for
critical conditions has been issued for both Saturday and Sunday
across the higher terrain areas east of Phoenix where the
probability of seeing winds reaching/exceeding 30 mph will be the
greatest.

Heading into next week, the ensemble guidance shows another ridge
building across most of the western CONUS. However, at the same
time, the guidance is also showing a couple of shortwave troughs
over the eastern Pacific undercutting the ridge that will likely
move over the Desert Southwest. The first shortwave will likely
move over the region late Monday into Tuesday with a follow on
shortwave moving in towards the latter half of the week. Both of
these systems will likely produce some enhanced breeziness as
well as keep any abnormal heat in check. The latest NBM shows
temperatures for most of next week fluctuating between the low to
mid 90s across the lower deserts.

&&

.AVIATION...Updated at 0522Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns are anticipated through the TAF
period. Winds will favor light, diurnal tendencies with speeds
generally under 10 kts and periods of variability throughout the
TAF cycle. Mostly clear skies will persist with some passing high
clouds.

&&

.FIRE WEATHER...
Abnormally hot conditions with temperatures across many of the
lower desert locations reaching into the triple digits can be
expected through the start of the weekend. A cooling trend is
expected by the end of the weekend through next week, however,
temperatures will still remain above normal. MinRHs through the
next several days for most of the area will remain in the single
digits with poor overnight recoveries. Winds through Friday will
remain light and follow the typical diurnal trends, with some
occasional afternoon upslope breeziness. By the weekend, as a
weather system passes to the north, winds are expected to increase
across the region with widespread afternoon/early evening peak gusts
between 20-30 mph, with locally higher gusts in excess of 30 mph
across the eastern districts. The combination of the gusty winds
and very dry conditions will result in elevated to locally
critical fire conditions. A couple of additional weather systems
will likely affect the region next week resulting in enhanced
breeziness and thus more elevated fire weather concerns.

&&

.CLIMATE...

Record high temperatures this week:

Date       Phoenix        Yuma        El Centro
----       -------        ----        ---------

Apr 10   100 in 2018   100 in 1960    98 in 2018
Apr 11    99 in 2023   101 in 1936   100 in 2018
Apr 12    99 in 1936   102 in 1962   103 in 1940

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Fire Weather Watch from Saturday morning through Saturday
     evening for AZZ133.

     Fire Weather Watch from Sunday morning through Sunday evening
     for AZZ133.

CA...None.
&&

$$

DISCUSSION...Lojero
AVIATION...Smith
FIRE WEATHER...Lojero
CLIMATE...Kuhlman