791
FXUS65 KPSR 230501
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1001 PM MST Wed Jul 22 2026

.UPDATE...Updated 06z 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/...
Early afternoon satellite WV imagery showed a weak cyclonic
circulation centered over southern Utah, aiding in thunderstorm
development around the Four Corners region. Further to the south
across south-central Arizona, drier conditions are beginning to
settle in with PWATs dropping to around 1.5-1.8" according to the
latest mesoanalysis. Given the drier, more stable atmosphere,
thunderstorm activity will be limited in coverage today and
primarily confined to the higher terrain/orographic features east of
Phoenix. NBM PoPs are highest across southern Gila County (~20%)
this afternoon, quickly dropping below 10% across the lower
elevations, before all areas see chances fall below 10% Thursday.

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 597-598dm.
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 0500Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation weather concerns are expected throughout the TAF
period. The overall wind pattern will continue to favor light and
diurnal tendencies along with extended periods of variable
conditions. FEW to occasionally SCT mid to high level cloud decks
with bases as low as 10 kft will be common throughout the period.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns under a FEW mid to high level
cloud decks are expected throughout the TAF period. The overall
wind pattern will favor light and diurnal tendencies along with
extended periods of variable conditions.

&&

.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...Smith/18
LONG TERM...18
AVIATION...Lojero
FIRE WEATHER...18