121
FXUS65 KPSR 021716
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1016 AM MST Sat Aug 2 2025

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- Hot temperatures with lower desert highs near or slightly above
  110 degrees will persist, resulting in at least widespread
  Moderate HeatRisk each day.

- Extreme Heat Warnings with areas of Major HeatRisk will affect
  portions of south-central AZ through this evening.

- Another more widespread Extreme Heat episode is expected by mid
  next week, with record high temperatures likely along with
  Major to Extreme HeatRisk.

- Overall dry conditions will prevail for much of the area with
  any rain chances remaining primarily confined to the higher
  terrain east of Phoenix.


&&

.SHORT TERM /Today through Sunday/...
The main weather story through the weekend will be the heat as a
strong ridge of high pressure currently centered near the AZ/MX
international border dominates over the region. The subtropical
ridge will reach its peak intensity today as 500 mb heights climb
to around 596-598 dm, which is above the 99th climatological
percentile. As a result, temperatures this afternoon will top out
well above normal with forecast highs upwards of 110-113 degrees
across the lower deserts. Afternoon highs in Phoenix will push
into record territory with a 70-80% chance of tying or breaking
the daily record high of 113 degrees. Given the unusually hot
temperatures, widespread Moderate HeatRisk will be in place today
with areas of Major HeatRisk across parts of south-central
Arizona. An Extreme Heat Warning remains in effect for much of
south-central Arizona through this evening.

Aside from the heat, the positioning of the aforementioned ridge
will lead to continued drying conditions as dry westerly flow aloft
prevails. This dry air is evident on early morning WV imagery and
the 00Z PHX sounding, which showed a dry atmospheric profile with
only a shallow layer of mid level moisture. Forecast soundings
indicate continued drying through tomorrow as PWATs bottom out
around 20-40% of normal. As moisture continues to get scoured out of
the region, HREF guidance indicates enough lingering moisture to
promote a small chance for an isolated shower or thunderstorm to
pop up over southern Gila County this afternoon with better
chances for convection remaining focused across far eastern and
southeastern Arizona. By Sunday, very dry conditions will be in
place eliminating any rain chances in the forecast.

&&

.LONG TERM /Monday through Saturday/...
The primary weather concern will be the unseasonably hot
conditions during the upcoming workweek. Starting off the
workweek, very dry conditions in place will allow for near normal
overnight lows Monday morning and will help to keep HeatRisk in
the Moderate category with localized areas of Major HeatRisk.
Going forward through the early part of next week, ensemble
guidance show the center of the subtropical ridge of high pressure
shifting eastward into southern NM while strengthening. By the
middle part of next week, ensemble and deterministic guidance show
500 mb heights peaking around 598-600 dm. The strength of the
ridge is likely to be in record territory for the climatological
period over the entire region Wednesday and Thursday. Temperatures
will quickly respond as daytime highs across the lower deserts
pushes to around 113-118 degrees. Record highs are likely to be
set with temperatures of this magnitude and may tie or break the
all-time hottest temperature for the month of August in Phoenix.
The hottest Phoenix has ever recorded in the month of August was
117 degrees which has happened 4 times (2011, 2015, 2020, and
2023). Overnight lows are also expected to climb into the lower
90s in Phoenix during this time, offering little overnight relief.
By the end of next week, the subtropical ridge is expected to
weaken, resulting in lowering temperatures.

With all that said, widespread Major to Extreme HeatRisk will
increase across most of the area by Wednesday and continuing through
Friday. Extreme Heat Watches remain in effect for south-central
Arizona starting Tuesday before expanding to include the entire CWA
Wednesday and continuing through Friday. Everyone should take extra
care next week to exercise heat safety to avoid heat-related health
issues.

The position of the ridge is expected to promote southerly moist
advection into the region going into Tuesday. Ensembles continue to
reflect a good deal of uncertainty in the amount of moisture we will
see pulled into the region. For now, the best chances for any
monsoon activity are expected to remain focused across the Rim and
down into southeastern Arizona.

&&

.AVIATION...Updated at 1715Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:

No major aviation concerns are anticipated through Sunday morning
under clear skies. Winds will follow a typical diurnal pattern
for this time of year, with occasional afternoon/early evening
gusts to 15-20 kts except at KIPL. At KIPL, light (AOB 6 kts) and
VRB winds through the afternoon will give way to west winds this
evening, with gusts potentially to 20-25 kts, though confidence is
too low in gusty conditions to include in the TAF.

&&

.FIRE WEATHER...
Drier conditions will continue to settle in this weekend with only
a small chance for an isolated shower or thunderstorm across
southern Gila County this afternoon. Min RHs will fall into the
5-10% range this weekend, while Max RHs range between 20-30% for
most areas. Winds will generally follow diurnal tendencies with
typical afternoon upslope gustiness. Temperatures will remain
above normal with lower desert highs mostly between 108-114
degrees. Overall dry and hot conditions will continue into next
week with any rain chances remaining mostly confined to the higher
terrain east of Phoenix.

to prevail
into next week with only very limited mostly high terrain chances
around Tuesday or Wednesday.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Watch from Wednesday morning through Friday evening
     for AZZ530>533-535-536.

     Extreme Heat Warning until 8 PM MST this evening for AZZ534-
     537>544-546-548>555-559.

     Extreme Heat Watch from Tuesday morning through Friday evening
     for AZZ534-537>563.

CA...Extreme Heat Watch from Wednesday morning through Friday evening
     for CAZ560>570.

&&

$$

SHORT TERM...Smith
LONG TERM...Smith
AVIATION...Whittock
FIRE WEATHER...Smith