Chiriaco Summit, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

128
FXUS65 KPSR 200600
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1100 PM MST Wed Aug 19 2026

.UPDATE...06Z Aviation Discussion

&&

.KEY MESSAGES...

- Scattered thunderstorms are expected this afternoon and evening
  across eastern and south-central Arizona. Strong gusty winds,
  blowing dust and locally heavy rainfall will be possible.

- Temperatures are forecast to remain several degrees above daily
  normals through the rest of the week with lower desert highs
  ranging between 107-113 degrees and overnight lows generally in
  the mid 80s to low 90s.

- Extreme Heat Warnings are in effect through Sunday evening due
  to continued areas of major HeatRisk.

- Thunderstorm chances will continue through Thursday before
  decreasing in coverage by Friday or Saturday.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
This evening and tonight remains to look promising with
thunderstorm and showers likely developing in the eastern AZ high
terrain and in Southern AZ. The subtropical ridge has promoted
easterly winds across the region and a gulf surge has lead an
increase in moisture with current PWATs between 1.5-1.6" for most
of south central AZ. This is a notable increase from 24 hours ago
where PWATs were generally between 1.2-1.3" across south central.
This moisture is expected to stay throughout today and tomorrow as
mixing ratios start to improve by this evening ranging between
10-12 g/kg. Current mesoscale analysis is already showing that the
high levels of CIN from this morning`s 12Z sounding are starting
to erode to near or below 100 J/kg with forecast models continuing
to show further eroding by this evening to mostly below 100 J/kg.
Additionally, MUCAPE forecasted to climb to at least 1000 J/kg
across all of southern and most of central Arizona to as high as
2000-2250 J/kg across southeast Arizona by early afternoon. Models
are in great agreement in scattered thunderstorms starting to
develop along the Mogollon Rim into the White Mtns and over
portions of southeast Arizona. With these storms outflows are very
likely and it is very plausible we will have colliding outflows
somewhere over the Phoenix metro late this evening giving rise to
additional storm development. SPC has upgraded Pinal County,
portions of southern Maricopa County, and the southern tip of Gila
County into a slight risk for severe storms and a Marginal risk
still remains across the remainder of Gila, and Maricopa County
for today. We also can`t rule out the threat for localized heavy
rainfall today, but storm movement should be enough to keep most
storms from producing more than an inch or so over any particular
location, but WPC has kept our region only in a Marginal risk for
excessive rainfall for today and tomorrow.

In addition to the chances for thunderstorms, another major impact
will be strong gusts and localized areas of dense blowing dust. With
the strong to severe storms likely tonight damaging winds will be a
concern, with DCAPE values forecasted  up to 1600, strong outflows
are projected for tonight. HREF currently shows a 50-70% chance of
gusts above 35 mph by this evening in eastern Maricopa County and
Pinal County. Due to these conditions a Blowing Dust Advisory
remains in place until 10PM MST tonight.

Models are continuing to show Thursday being another fairly active
weather day as moisture will remain plentiful across the area and
the subtropical high center moves to over the Four Corners area.
However, depending on how active tonight ends up being the
atmosphere may be too worked over by tomorrow evening to produce
much in terms of severe storms, and lingering clouds well into the
morning hours may also inhibit heating, keeping instability lower
than today. That being said, if today is not as active as
anticipated, Thursday is likely to be the biggest storm coverage
day.

Hot and humid conditions are expected today with lower desert
afternoon highs between 108-112 degrees, but much higher heat
indices are forecast for locations across southeast California
through the Lower CO River Valley. Expect late afternoon heat
indices of 113-120 degrees in the aforementioned areas.
Temperatures are more uncertain for Thursday due to potential
impacts from storms this evening and lingering clouds, but NBM
guidance indicates very similar highs and heat indices again
breaching 110 degrees over the majority of the lower deserts.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Hot and somewhat humid conditions are expected to prevail through
the upcoming weekend with a high probability of the Extreme Heat
Warnings being extended soon. Forecast uncertainty has been an
issue for late this week into the weekend as storm chances were
higher with model runs earlier this week. However, it now seems
more likely than not drier air will move into the area beginning
Friday leading to much more limited shower and storm chances
through the upcoming weekend. The lower storm coverage and fairly
consistent upper level heights should keep daily highs right
around 110 degrees or even a couple degrees above through the
weekend. Guidance does hint at some better moisture advecting into
the area early next week, but the latest trends show the ridge
center drifting back toward our region. If that holds true, our
convective potential should remain on the lower side with little
to no relief from the hot temperatures.

&&

.AVIATION...Updated at 0600Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
The main aviation concern will be focused over the next few hours
with lingering shower and thunderstorm activity. Gusty and erratic
winds along with reduced VIS will be the main concerns through
about 07-08Z. Further SHRA/TSRA activity will be possible as far
as 11-12Z, but direct impacts at the terminals is less certain
during this timeframe. Conditions should dry out by sunrise. As
long as the rainfall remains in the vicinity, erratic winds may be
common through much of the night and even as far as the morning
hours. Westerly winds will become established earlier than usual
by the late morning timeframe. Another window of outflow potential
will exist Thursday evening, but timing and strength remains
uncertain at this time.


Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns are expected during the next 24
hours. Winds will favor a SE`rly component at KIPL, while SSE to
SW`rly directions will be common at KBLH. Periods of VRB
conditions may be observed around the dawn at each terminal. SCT
cloud decks will be present through much of the forecast window,
with the lowest bases around 15 kft.


&&

.FIRE WEATHER...
For today, expect above normal temperatures with increasing
moisture and rain chances. Scattered thunderstorms producing
gusty winds are likely to impact the eastern districts from late
afternoon through this evening. Elevated moisture levels will
persist through Thursday with additional chances for scattered
showers and storms before some slight drying and lower rain
chances occurs Friday into the weekend. MinRHs of 20-30% are
anticipated through Thursday before lowering to 15-25% beginning
Friday. Outside of gusty and erratic winds near any thunderstorm,
overall winds will follow the typical diurnal tendencies with some
modest afternoon upslope gustiness.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Sunday for AZZ530>544-546-
     548>551-553>555-559-560.

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

&&

$$

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