026
FXUS65 KPSR 251720
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1020 AM MST Tue Aug 25 2026

.UPDATE...18Z Aviation Discussion.

&&

.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 essentially come to an end starting
  today before slowly returning this coming weekend.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
GOES mid-level WV imagery and RAP40 500mb analysis show southerly
flow aloft with dry air being advected into the region. The
subtropical high is currently positioned over southeastern NM and
western TX, but over the course of this week the core of the high
will push westwards and sit over southeastern AZ/ southwestern NM.
This will lead to winds aloft shifting out of the south to
southwest, further drying the atmosphere. Ensembles show PWATs
falling to near 80% of normal, additionally 1000- 700mb mixing
rations are also forecasted to fall to between 6-7 g/kg. H5
heights associated with the high will most likely peak by
Wednesday between 594-597 dam, or near climatological maximum for
late August. This will correlate to afternoon highs in across the
lower deserts to be between 110F-115F (5F-10F above normal).
Overnight lows will offer very little relief from this heat, with
lows throughout the week continuing to be in the upper 80s to
lower 90s. These conditions has lead to widespread Major to
Extreme HeatRisk across the region and as a result an Extreme Heat
Warning will remain in effect through Saturday for the lower
deserts, and has been expanded to include JTNP, Globe, and Tonto
Basin through Friday evening.

&&

.LONG TERM /FRIDAY THROUGH SUNDAY/...
Ensembles continue to point towards the subtropical high shifting
back eastwards starting Friday as a troughing feature moves
into the Northwestern U.S./ Canadian boarder. As the trough
pushes eastwards PWATs begin to improve, being back above normal,
near 1.5"-1.7" by Saturday, and is expected to remain through at
least the weekend. 1000-700MB mixing ratios are forecasted to be
generally back above 10 g/kg which should be enough for rain
chances to return to the region as the NBM/WPC PoPs are currently
reflecting a 20-30% chance. This is a decent increase from
previous runs but still several days out so models are still
subject to change, but currently looks promising for at least the
eastern high terrain. Temperatures will notably reduce by Sunday
for most of the region, falling to near normal.

&&

.AVIATION...Updated at 1720Z.

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

No aviation weather concerns are anticipated under periods of FEW
to SCT mid/high cloud decks. The overall wind pattern will follow
the typical diurnal trends with speeds generally aob 8 kts.
Periods of light and vrb can also be expected, especially during
diurnal transitions. Winds may be slower to transition out of the
west on Wednesday morning.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns are expected under periods of FEW to
SCT mid/high cloud decks. Winds will generally fluctuate between
the SE to W at KIPL and S to SW at KBLH with speeds remaining aob
10 kts at both terminals. Extended periods of light and vrb winds
will be common during the early morning hours.

&&

.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 will
mostly fall into the teens starting today. 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 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.

     Extreme Heat Warning until 8 PM MST Friday for AZZ556-561-562.

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

     Extreme Heat Warning until 8 PM PDT Friday for CAZ561-563-564-
     568.

&&

$$

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