Chiriaco Summit, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

214
FXUS65 KPSR 050005
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
505 PM MST Wed Jun 4 2025

.UPDATE...Updated 00Z Aviation Discussion.

&&

.KEY MESSAGES...

- Scattered showers and storms are expected over Northern Arizona
  through the rest of the day, with isolated activity over the
  South Central Arizona high terrain over the next few hours.

- Conditions return to seasonably hot and dry by the end of the
  workweek and through the weekend.

- Areas of Moderate HeatRisk develop by Saturday and become more
  widespread by Sunday.

&&

.DISCUSSION...
Current upper level objective analysis places the center of a low
over Central AZ. As the upper low continues to eject
northeastward, a midlevel subsidence inversion is shown developing
over much of the eastern CWA, precluding the development of any
robust shower/storm activity over South-Central AZ, however, this
midlevel inversion is much less pronounced in GFS bufr soundings
for points in the western CWA. As such, some deeper updrafts could
potentially form further west, though midlevel lapse rates are
still quite low, CAPE is skinny, and LCLs are high. Latest runs of
some CAMs feature isolated convective showers forming over the
Kofa, Chocolate, and Western JTNP Mountains, consistent with
current cumulus buildups seen in visible satellite imagery.
Meanwhile, some lingering showers have been passing over portions
of Southern Gila County since late this morning, and this activity
has already lessened considerably. All convective activity over
the forecast area should cease before sunset. Overall, expect
little to no additional rainfall from any convective showers
through the remainder of the afternoon, though a few strikes of
lightning cannot be ruled out.

For the remainder of the workweek, ensembles show some level of
positively-tilted broad troughing will exist over the Western US,
but a subtropical ridge will start to edge closer from the
southeast, bringing positive midlevel height anomalies overhead.
As a result, expect thermal profiles to warm through the end of
the workweek, with a return to triple digit highs for the
typically hotter locales on Thursday (65% chance for 100+ deg F
at Phoenix Sky Harbor by Thursday, and 98% chance by Friday.)

By the weekend, ensembles show the forecast area solidly under the
influence of the aforementioned subtropical ridge, with another
upper level East Pacific ridge positioning itself off the Pacific
Northwest Coast. In between these features, a cutoff low is
pinched off the base of the broad Western US troughing and
retrogrades west of California (almost directly south of the East
Pacific ridge.) With the subtropical ridge overhead, expect H5
heights to peak around 590 dam. The latest NBM advertises lower
desert highs peaking around 105-109 on Sunday-Monday, with a
10-20% probabilities of reaching 110F at Sky Harbor and around
30% probabilities for that over portions of Southeast CA. With
these forecast highs, Moderate HeatRisk will develop over the
region this weekend, but it seems temperatures will not reach
Extreme Heat levels. Guidance then mostly favors the cutoff low
moving from just off the California Coast over the weekend into
or near our region by around next Tuesday. This feature is not
likely to bring much change for our region as it looks quite dry,
but it may be enough to drop daytime highs back into the normal
range by the middle of next week.

&&

.AVIATION...Updated at 0005Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
A light shower developed near KPHX, moving northeast. This shower
and any other that may pop up will be short-lived and should all
dissipate over the next 1-2 hours. No additional rain is expected
through the remainder of the TAF period following this. Winds will
tend to follow typical diurnal tendencies, with speeds mostly <10
kts and periods of light variability, through the period. Skies
become mostly clear this evening and will remain that way through
Thursday afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH:
No significant aviation concerns throughout the TAF period with
mostly clear skies prevailing. Winds at KIPL will favor S-E
directions and S directions at KBLH. Wind speeds at both terminals
will remain mostly at or below 10 kts.

&&

.FIRE WEATHER...
A weather system will exit the region later today with lingering
chances for showers and isolated thunderstorms into the afternoon
across the Arizona higher terrain. Drying conditions and hotter
temperatures are then expected through the rest of the week.
MinRHs will remain elevated today at mostly above 20-25% before
lowing to 10-15% by Friday. Winds should follow fairly typical
diurnal tendencies with periodic afternoon upslope gustiness.
The dry weather pattern is expected to continue through the
weekend into early next week with temperatures running 5-10
degrees above normal and daily MinRHs mostly in a 5-10% range.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

DISCUSSION...Whittock
AVIATION...Benedict
FIRE WEATHER...Whittock/Kuhlman