300
FXUS65 KPSR 242052
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
152 PM MST Mon Aug 24 2026

.KEY MESSAGES...

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

- Lower desert highs are likely to reach or exceed 110 degrees
  through the rest of the work week and even into the weekend,
  peaking around daily records during the middle of the week.

- Monsoon storm chances will be very limited this week and
  essentially come to an end by Tuesday before slowly returning
  this coming weekend.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
An expansive subtropical anticyclone can be seen in midlevel
water vapor imagery centered over Southern NM/far Western TX,
resulting in southerly to southeasterly flow aloft. A pocket of
considerably drier air is evident nudging into Southeastern AZ and
will continue to filter into the area as we head into the middle
of the work week. Shower/thunderstorm activity from yesterday
evening has effectively overturned the atmosphere over South-
Central AZ, evident in the 12Z PSR sounding which shows a nearly
moist adiabatic temperature profile above the boundary layer and
only skinny elevated CAPE between approximately 600-400 mb.
Inhibition is very unlikely to be overcome across the eastern CWA
this afternoon/evening, except maybe for a couple thunderstorms
over the most prominent terrain of Southern Gila County. However,
the same cannot be said about portions of the western CWA.
Marginally supportive low level moisture remains in place across
Southwest AZ and Southeast CA with near surface mixing ratios
between 9-11 g/kg and RAP analyzed PWATs between 1.4-1.7". While
CIN is still high (-50 to -125 J/kg), there may be a window late
this afternoon where outflows from the Baja Spine could spark some
strong to severe storms over Imperial County. This is a very low
probability, but the potential is worth mentioning. Otherwise,
anticipate 10-20% chances for isolated thunderstorms over
prominent terrain features near JTNP, the Kofa Mountains in
Southwest AZ, and perhaps the Harcuvar Mountains.

Ensembles remain in excellent agreement that the subtropical
anticyclone will continue shifting westward and strengthen
gradually heading into the middle of the work week. With the
center of the anticyclone settling along the AZ/NM border,
ensemble mean H5 heights by Wednesday will reach a 595-597 dam
range, around the 98th-99th percentile of climatology. NAEFs mean
850 mb temperatures respond quickly, with values peaking around
29C-32C, near climatological maximum for late Summer. This will
support lower desert afternoon highs around 10F above daily
normals, near record highs through the middle of the week. This
will follow overnight lows in the 80s to around 90F, offering
little overnight relief from the heat. Extreme Heat Warnings
remain in effect through Saturday across much of the area and will
likely need to be expanded to cover communities such as Globe,
Tonto Basin, and rural communities outside the typically hotter
lower desert locales during the latter half of the week. The other
result of the high settling closer to the forecast area will be
increasing midlevel subsidence and weak, if any, midlevel flow.
Better quality moisture will be confined to our south, mostly over
Sonora, with 1000-700 mb mixing ratios remaining low, 6-8 g/kg
over the forecast area. The result of this increased subsidence
and meager moisture will be a near complete suppression of
thunderstorm activity by Tuesday-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 1755Z.

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

No major aviation concerns are expected through this TAF period.
As morning storms continue to move out of the region expect
periods of southerly winds gusting up to 20kts. Diurnal shift out
of the west will occur around the 20z timeframe. Winds will
generally be aob 10kts or less. However, some elevated wind speeds
with gusts in the mid-upper teens will be possible later this
afternoon/evening. SCT-BKN mid/high cloud decks will be common
throughout this afternoon into this evening, clearing out tomorrow
morning. The diurnal shift out of the east this evening is
forecast to occur around 11z with wind speeds expected to be aob
5-8 kts.

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 south aob 8-10 kts becoming light and variable later this
evening with mostly clear skies.

&&

.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. Outside of distant thunderstorm
outflows, 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...Whittock
LONG TERM...Kuhlman
AVIATION...95/Ryan
FIRE WEATHER...Kuhlman/Whittock
CLIMATE...18/Kuhlman