570
FXUS65 KPSR 221100
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
400 AM MST Sat Aug 22 2026

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- High temperatures reach or exceed 110 degrees nearly every day
through the next week and will be within a few degrees of daily
records, while morning lows remain unusually warm.

- Extreme Heat Warnings are in effect through Friday evening with
daily major to extreme HeatRisk.

- Thunderstorms will primarily favor higher terrain areas through
early next week, with drier and less favorable conditions next week.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...
Extreme heat will be the primary weather hazard through the short
and long term forecast. Early morning objective analysis shows a
596dm high pressure centered over CO/NM. Models show that this high
will slowly progress eastward through the beginning of next week.
Despite the center of the high moving away from our region, H5
heights over our region will remain in a 594-597dm range. With
heights of this magnitude, the NBM continues to show afternoon highs
(morning lows) of 110-116 (83-91) degrees across the lower deserts
and 100-110 (70-80) degrees across the higher terrain areas.
Temperatures of this magnitude are 5-8 degrees above daily normals
and some locations could tie or break their daily records (see
Climate section below). These temperatures will lead to widespread
high-end moderate to major HeatRisk across much of the CWA and
therefore the Extreme Heat Warning remains in effect.

The best thunderstorm chances will exist across the higher terrain
areas through the beginning of next week with only slight chances
for some isolated activity across the lower deserts. Thunderstorm
chances across the lower deserts for this afternoon are around 10-
20%. While some hi-res models (HRRR and RRFS) are trying to pick up
on some more scattered activity across south-central AZ (including
the Phoenix Metro), they are likely overdoing the coverage. Models
show limited moisture today (PWATs of 1.0-1.3"), mixing ratios only
around 6-7 g/kg, MUCAPE values less then 500 J/kg, and around 25-50
J/kg of CIN. The hi-res models showing scattered to widespread
activity for this evening are likely picking up on some upper-level
divergence and colliding outflows. While there will likely be
multiple outflows moving off the higher terrain this evening not
much activity (other than some isolated showers and maybe a few
isolated storms) is expected even if they do collide due to all the
limiting factors mentioned earlier. Strong to locally severe wind
gusts and areas of blowing dust will be the primary hazard with any
storm this afternoon and evening, with high DCAPE values (1800-2000
J/kg).

Models are in decent agreement that there will be a slight increase
in moisture on Sunday and Monday (PWATs increase to around 1.1-1.6"
across the area) with the highest moisture expected on Monday.
Instability will be about the same on Sunday as today, but will
increase to around 1000-1500 J/kg on Monday. Additionally, mixing
rations will increase to around 10 g/kg on Monday. Despite the
increase in moisture, instability, and mixing ratios models show an
increase in CIN (100-200 J/kg). Activity each day will depend on how
the day prior plays out. But right now, Monday looks to have
slightly better chances than Sunday. Either way, most of the lower
deserts are expected to remain dry with the best chances (and
coverage) of thunderstorms expected across the higher terrain areas
to the east of the Phoenix Metro.

&&

.LONG TERM /TUESDAY THROUGH NEXT FRIDAY/...
Ensemble members are in good agreement that by Tuesday drier air
will start to filter back into the region as the subtropical high
starts to retrograde back over our region. By the middle of the week
the center of the high will be straddling the AZ/NM border and by
the end of the week the center of the high will be over AZ. As the
high moves overhead, PWATs will drop into a 0.8-1.2" range across
our region and steering flow will be out of the S/SW. The
combination of these factors will lead to poor chances for
thunderstorm development across the region. The NBM shows that
Tuesday and Wednesday there could be enough moisture around to
support isolated thunderstorm chances for the higher terrain areas.
But by the end of next week thunderstorm chances for our area shut
off and will mainly be relegated to the Mogollon Rim.

Unusually hot temperatures will be the main story next week. As
mentioned above the subtropical high will slowly retrograde back
over our region beginning on Tuesday, which will result in a gradual
warming trend for our area. The high is also expected to strengthen
to around 596-598dam during this time. The combination of the center
settling over our region and strengthening will result in
temperatures heating up to around 10 degrees above normal for this
time of year. Afternoon highs (morning lows) are forecasted to be in
the 110-116 (85-95) degree range across the lower deserts and in the
100-110 (75-85) degree range across the higher terrain areas. The
increase in temperatures will also result in an increase in
HeatRisk, with widespread extreme HeatRisk forecast for the majority
of the CWA by Wednesday. There remains high confidence in the heat
forecast for next week. So, the Extreme Heat Warning remains in
effect through next Friday and will likely need to be expanded to
more areas by the middle of the week and may eventually need to be
extended into next weekend.

&&

.AVIATION...Updated at 1100Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Uncertainty in TSRA/SHRA coverage and corresponding gusty outflow
winds/wind shifts will be the primary forecast challenge through
Sunday morning under periods of mid/high cloud decks. Confidence is
good that light east winds will prevail through early/mid afternoon
with a slow transition to W/SW by late afternoon. TS development
over higher terrain areas may send gusty outflow winds towards the
Phoenix terminals during the early evening with a S/SE direction
most likely. While direct TS impacts are not likely, briefly gusty
winds and decaying SHRA could affect operations mid evening. If more
concentrated storms can materialize along with multiple colliding
outflow boundaries, better chances for isolated TS development in
lower elevations will be enhanced with stronger and more prolonged
wind gusts.


Southeast California/Southwest Arizona including KIPL and KBLH:
No major weather issues will exist through Sunday morning under
mostly clear skies. Trends in winds should be similar to the past 24
hours, generally varying between SE and SW with extended periods of
nearly calm conditions in between. TS activity over the Baja spine
late this afternoon may send an outflow and decaying SHRA towards
KIPL prior to sunset. Chances for direct TSRA impacts are too low to
include in this TAF package, however gusty SW winds justify a
continued mention through the early evening.

&&

.FIRE WEATHER...
Hot and seasonally dry conditions are expected nearly every day,
through next week. Aside from a brief increase in moisture Sunday-
Monday, minimum RH values each afternoon will be around 12-18% (15-
25% Sun-Mon). Temperatures will be around 5-10 degrees above normal
through the next week, with lower desert highs eclipsing 110 degrees
most afternoons. There will be slight chances for storms each
afternoon through Monday, but they will mostly favor the higher
terrain areas. Drier conditions, with lower storm chances are
expected by the middle of next week. Outside of thunderstorm outflow
winds, winds will follow the typical diurnal tendencies with some
modest afternoon upslope gustiness.

&&

.CLIMATE...
Record highs:

Date       Phoenix         Yuma         El Centro
----       -------         ----         ---------
Aug 22   113 in 2011    115 in 1969    117 in 1969
Aug 23   114 in 2011    115 in 2011    116 in 1969
Aug 24   115 in 2020    119 in 1985    117 in 1985
Aug 25   113 in 2011    116 in 1962    117 in 1962
Aug 26   117 in 2011    115 in 2020    115 in 1981
Aug 27   114 in 2023    120 in 1981    117 in 1981
Aug 28   117 in 2023    118 in 2023    117 in 2009

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Friday for AZZ530>555-559-
     560.

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

&&

$$

SHORT TERM...Berislavich
LONG TERM...Berislavich
AVIATION...18
FIRE WEATHER...Berislavich/Benedict
CLIMATE...18