768
FXUS65 KPSR 241050
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
350 AM MST Mon Aug 24 2026

.UPDATE...12Z Aviation Discussion

&&

.KEY MESSAGES...

- Extreme Heat Warnings remain in effect through Saturday with
  daily Major to Extreme HeatRisk.

- High temperatures will reach or exceed 110 degrees nearly every
  day this week, peaking right around daily records Tuesday
  through Thursday.

- Monsoon storm chances for the upcoming workweek will be very
  limited with chances briefly coming to an end starting Tuesday
  before slowly returning by next weekend.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
Early morning lingering showers and a few thunderstorms will
gradually diminish by sunrise leaving a somewhat overturned
atmosphere and slightly cooler temperatures across much of
southern and central Arizona. The subtropical high, which is
currently centered along the New Mexico/Texas border, is set to
shift westward today into Tuesday with the center reaching
western New Mexico on Tuesday. Drier air is already starting to
move in from the south and this will continue through at least
Tuesday, dropping low level mixing ratios to between 6-8 g/kg.
This drier air in combination with increasing subsidence from the
ridge will basically end rain chances beginning Tuesday. For today
however, there should still be enough lingering moisture and not
too high of CIN for a few isolated showers or weak storms across
higher terrain areas across Arizona and southeast California. Rain
chances should then fall to below 10% starting Tuesday and likely
stay that way through Thursday with the ridge eventually moving
directly over southeast Arizona and southwest New Mexico.

The main forecast concern for the rest of the week will be the
late August extreme heat. Extreme Heat Warnings remain in effect
for the majority of the area through Saturday with expectations of
some expansion of the warning into higher terrain locations for
the latter half of the week. The slightly rain-cooled air should
keep daytime highs today mostly in a 106-110 degree range, but
that will quickly change beginning Tuesday. The drying conditions
and increasing heights for the middle part of the week are
expected to push daytime highs well above 110 degrees. The latest
NBM temperatures have trended downward over the past couple of
days of runs, but with the NBM`s recent track record of under
doing temperatures, we have bumped highs up a degree or two.
Daytime highs are likely to reach 112-116 degrees Tuesday through
Thursday, potentially tying or breaking a few daily records. Very
warm overnight lows are also forecast, eventually leading to
fairly widespread Extreme HeatRisk by Wednesday.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
Ensemble guidance favors some weakening of the subtropical high
starting Friday as it starts to shift back to the east. This shift
assumes a Pacific trough moving into the Northwestern U.S. late
week. Models also favor some gradual moisture advection by Friday
and lasting through the upcoming weekend. Given the expected
increase in moisture and weakening subsidence, rain chances should
return as early as Friday but more likely over the weekend.
NBM/WPC PoPs show 10-15% chances over high terrain areas Friday
and Saturday before increasing and expanding into the lower
deserts by Sunday. These PoPs may be underdone somewhat
considering what the latest models runs show, so we anticipate
higher PoPs soon from the NBM. Temperatures should also begin to
improve late week and through the weekend as moisture increases
and heights gradually lower. The latest forecast highs still
maintain or even top 110 degrees through Saturday before dropping
to below 110 degrees by Sunday or Monday of next week.

&&

.AVIATION...Updated at 1045Z.

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

No major aviation concerns are expected through this TAF period.
The storms that brought gusty winds, thunderstorms and reduced
visibilities last night have moved away from the terminals are is
now expected to go back to mostly diurnal tendencies with periods
of VRB and an early westerly shift by 18Z this morning. Winds
will generally be aob 10kts, however some elevated wind speeds
with gusts in the low-mid teens will be possible later this
afternoon/evening. FEW- SCT high cloud decks will be common
throughout the period.

Southeast California/Southwest Arizona including KIPL and KBLH:

No major aviation concerns under FEW-SCT mid/high cloud decks can
be expected throughout the TAF period. Winds will generally be out
of the southeast at KIPL and will fluctuate between the south-
southeast to southwest at KBLH. Overall wind speeds will range
between 8-15 kts, highest at KBLH.

&&

.FIRE WEATHER...
Hot and seasonally dry conditions will prevail for much if not all
of the coming week. Strong high pressure will settle over the
region by midweek with gradual drying conditions. Minimum RHs
today will mostly fall between 20-30%, before dropping back into
the teens starting Tuesday. Temperatures will be around 5-10
degrees above normal, with lower desert highs eclipsing 110
degrees nearly every afternoon. Expect overall light winds
following typical diurnal tendencies with some modest afternoon
upslope gustiness.

&&

.CLIMATE...
Record highs:

Date       Phoenix         Yuma         El Centro
----       -------         ----         ---------
Aug 24   115 in 2020    119 in 1985    117 in 1985
Aug 25   113 in 2011    116 in 1962    117 in 1962
Aug 26   117 in 2011    115 in 2020    115 in 1981
Aug 27   114 in 2023    120 in 1981    117 in 1981
Aug 28   117 in 2023    118 in 2023    117 in 2009
Aug 29   116 in 2023    117 in 1954    117 in 2005

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Saturday for AZZ530>555-559-
     560.

CA...Extreme Heat Warning until 8 PM PDT Saturday for CAZ562-565>567-
     569-570.

&&

$$

SHORT TERM...Kuhlman
LONG TERM...Kuhlman
AVIATION...Ryan/Lojero
FIRE WEATHER...Kuhlman
CLIMATE...18/Kuhlman