666
FXUS65 KPSR 221729
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1029 AM MST Wed Jul 22 2026

.UPDATE...Updated 18z Aviation Discussion...

&&

.KEY MESSAGES...

- Temperatures will increase significantly the remainder of the week
with Extreme Heat Warnings in effect as readings approach near
record levels.

- High pressure responsible for the extreme heat will also restrict
thunderstorm development with chances retreating well into the
mountains through the weekend.

- Above normal temperatures may begin to relax early next week as
better thunderstorm coverage returns to the region.

&&

.SHORT TERM /Today through Friday/...
A well defined easterly wave, now in the form of a closed
circulation was slowly migrating north along the Arizona/New Mexico
border early this morning. With this evolution, favorable divergence
aloft and downstream vorticity advection on the northern and western
periphery of the gyre were exiting the forecast area. In its place
as the vorticity center ejects into the central Rockies, deeper NW
flow and subsidence will become more pronounced over the next 36
hours as subtropical ridging retrogrades from the southern plains.
While this pattern will not completely scour away moisture, the
current 10-14 g/kg boundary layer mixing ratios will be replaced by
9-10 g/kg levels. Coincident with notable warming aloft, this will
heighten CinH and limit available MLCape such that even deep
convection over higher terrain locations may struggle. HREF output
reflects this with only isolated pulse driven deep convection this
afternoon, followed by essentially a completely dry forecast
Thursday and Friday.

The larger weather hazard over the next several days will be
building heat as strong subtropical ridging retrogrades back into
the SW Conus. Ensemble members are in excellent agreement depicting
the central anti-cyclone becoming established over western New
Mexico by Friday with H5 heights settling near 598dm. Surprisingly
given the agreement among the entire ensemble suite, numerical
spread is fairly wide likely owing to differences in boundary layer
moisture content across the CWA. Given the current low level
dewpoint status in south-central Arizona and lack of strong flow
throughout the troposphere, it`s more likely modest moisture lingers
and some of the more extreme forecasts above the 75th percentile
will not come to fruition. However across the western CWA where
moisture is not as plentiful, upper end readings above 115F will be
more likely. Regardless, widespread major HeatRisk (and local
extreme HeatRisk) with afternoon highs 5F-10F above normal will
become common, and an Extreme Heat Warning continues.

&&

.LONG TERM /Saturday through Tuesday/...
Strong high pressure will continue to be the dominant synoptic
feature through early next week with H5 heights 596-598dm sprawling
across the forecast area. Unsurprisingly given this pattern,
widespread major HeatRisk will continue with clear cut warning
criteria persisting through the weekend as temperatures hover 5F-10F
above normal. The preponderance of ensemble output suggests the
center of the subtropical anti-cylcone slowly lifting through the
four corners and into Colorado during the first part of next week
allowing easterly flow, subtle shortwaves, and stronger, moist
outflows to return to Arizona. Easterly wave energy will also help
erode some of the higher midlevel heights and temperatures while
also aiding the displacement of the anti-cyclone center. These
combined efforts should allow local H5 heights to fall below 594dm
though the timing at which this evolution occurs is somewhat
uncertain. Among GEFS members, there is fairly convincing evidence
of enhanced convection Sunday allowing deeper outflow intrusions
while H5 heights fall below 594dm reducing or eliminating the
extreme heat threat Monday. EPS members are more suggestive of
better convective potential delayed until Monday evening, but
regardless temperatures should return to near normal levels by the
middle of next week with the diurnal thunderstorm risks also
returning to the region.

&&

.AVIATION...Updated at 1728Z.

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

No major aviation weather concerns are expected throughout the TAF
period. Expect light winds throughout the period generally
following diurnal switches, but also with periods of variability.
SCT-BKN clouds aoa 10 kft will become FEW-SCT by later this
afternoon.

Southeast California/Southwest Arizona including KIPL
and KBLH:

No major aviation weather issues under few passing mid/high cloud
decks can be expected throughout the TAF period, but remaining
mostly clear. Winds will by diurnal at KIPL with periods of light/VRB
winds. While winds at KBLH will favor the south, slowly shifting
out the SW by late tonight.


&&

.FIRE WEATHER...
Thunderstorm chances will dwindle the remainder of the week with
only slight chances remaining over high terrain areas of far eastern
districts. Instead, temperatures will warm significantly with much
above normal readings and Extreme Heat Warnings. Despite the warmer,
drier conditions, humidity levels will not fall substantially with
minimum afternoon readings 15-30% the next couple days falling
closer to a 10-25% range over the weekend. Correspondingly,
overnight recovery will mostly stay in a fair to good range of 30-
60%. Winds should be fairly light through the period with only local
afternoon gusts 20-25 mph.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Monday for AZZ530-532.

     Extreme Heat Warning from 10 AM Thursday to 8 PM MST Monday for
     AZZ531-533>555-559.

CA...Extreme Heat Warning until 8 PM PDT Monday for CAZ562>570.

     Extreme Heat Warning from 10 AM Thursday to 8 PM PDT Monday for
     CAZ560-561.

&&

$$

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

NWS PSR Office Area Forecast Discussion