Chiriaco Summit, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

881
FXUS65 KPSR 221721
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1020 AM MST Sun Jun 22 2025

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- Below normal temperatures the next several days followed by a
return to above normal as early as Thursday with lower desert highs
returning around 110 degrees next weekend

- Dry conditions will prevail under mostly clear skies with
afternoon and evening breeziness (15 to 25 mile per hour gusts)

- Slight chances (10 to 20 percent) for afternoon storms in parts of
Southern Gila County beginning Tuesday

&&

.DISCUSSION...
Widespread heat alerts are seen from the Midwest through the
Northeast, while there are winter weather and freeze alerts in parts
of the Northwest. The yin and the yang, with a large area of high
pressure across much of the eastern CONUS and an anomalously cool
trough across the western CONUS. This trough across the West will
lead below normal temperatures today through at least Tuesday, with
today expected to be the coolest day in the forecast. Most lower
desert locations will come up short of 100 degrees this afternoon,
which is rare for late-June. Phoenix has only observed a sub-100
degree high 7 times between June 20th-30th during the 2000s (Yuma 11
times & El Centro 13 times). The morning low temperatures will also
be more pleasantly in the upper-60s to middle-70s through mid-week.

Unfortunately, the sub-seasonal temperatures will not last as global
models continue to show the trough in the West gradually weakening
and negative height anomalies disappearing by Thursday. The negative
height anomalies will not be immediately be replaced by positive
anomalies and strong high pressure, as the blocking high/heat dome
in the East is expected to persist through most of the week. H5
heights are still expected to slowly rise across the Desert
Southwest, however, and so will surface temperatures as a result.
Latest NBM forecast has a return to above normal as early as
Thursday and then 110 degree highs by next weekend.

With the trough still in the West, daily breezy conditions will
continue across the region, though winds will not be as strong as
the past couple of days. Winds are actually still quite breezy (25-
35 mph gusts) across Southeast CA early this morning, with westerly
downsloping winds in Imperial County and northwesterly winds behind
a dry cold front that has dropped down into eastern Riverside
County, but these winds will subside through the morning and become
light by this afternoon. Afternoon 15-25 mph gusts will be common
through the next several days.

So, when will monsoon storms get going here? Well, while the western
trough lingers across the area through early week it will maintain
dry southwest flow across Southeast CA and most of AZ and keep a
deeper moisture axis off to the east and southeast in New Mexico and
northern Mexico. As the trough weakens by midweek moisture levels
are expected to start rising across southeast and south-central AZ,
more to seasonal levels (lower desert PWATs of 0.7-0.9"). This looks
like it will lead to at least some isolated storms developing in
parts of southeast AZ beginning around Tuesday, including as far
north as the White Mountains and into Gila County. Grand ensemble
probabilities >50% for MUCAPE >200 J/kg suggests afternoon and
evening storms will mostly stay east of a line from Tucson through
Globe Tuesday through Friday. The MUCAPE probabilities then drop
heading into next weekend, suggesting a decrease in activity. NBM
PoPs in southern Gila County only peak around 10-20% Tuesday-Friday.

Looking a little further ahead, long-range models are not indicating
any strong signals for anymore negative height anomalies across the
West and there is consensus for the monsoon high becoming
established in the Desert Southwest around or just after July 4th.
Overall, it is looking like we will slowly ease our way into the
monsoon stormy season with moisture levels slowly creeping up.

&&

.AVIATION...Updated at 1720Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major weather issues will exist through Monday afternoon under
clear skies. Confidence is excellent that wind speeds will be much
weaker than the past 24 hours, though a few gusts around 20kt are
possible late afternoon/early evening. Timing of wind shifts will be
seasonally typical, however extended periods of variability (or
southerly cross runway component) during the transitions times may
be more common this TAF cycle.


Southeast California/Southwest Arizona including KIPL and KBLH:
Uncertainty regarding smoke/haze from wildfires across the
international border is the primary forecast challenge this periods
under otherwise clear skies. Confidence is excellent that wind
speeds will be much weaker than the past 24 hours with little
gustiness through the period. W/NW directions will be preferred much
of the time frame, however extended periods of variability are also
possible. While much of the smoke/haze will likely be lofted
impacting slantwise visibilities, there may be some minor surface
impacts as well depending on progress in wildfire management.

&&

.FIRE WEATHER...
There are no considerable fire weather concerns through the next 7
days, aside from perhaps some isolated dry thunderstorm impacts in
parts of southern Gila County (toward the White Mountains) beginning
Tuesday. Winds will be lighter than the previous couple of days, but
still breezy in the afternoons and evenings with daily peak gusts up
to 15-25 mph. Conditions overall will remain dry with daily minimum
RH values down to 5-15% and overnight recoveries only to 20-40%.
Near to below normal temperatures are expected through the first
half of the week, but will warm through the end of the week and
lower desert highs will push back to around the 110 degree mark by
next weekend.

&&

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

&&

$$

DISCUSSION...Benedict
AVIATION...18
FIRE WEATHER...Benedict