666
FXUS65 KPSR 231758
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1058 AM MST Sun Aug 23 2026

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- Isolated to scattered thunderstorms, some strong to possibly
  even severe, are expected this evening across south-central
  Arizona.

- Increasingly less favorable conditions for thunderstorms will
  develop starting Monday with virtually no chances for rain from
  Tuesday through the rest of the week.

- High temperatures will reach or exceed 110 degrees nearly every
  day this week and will be near daily records, while morning
  lows remain unusually warm.

- Extreme Heat Warnings are in effect through Saturday with daily
  Major to Extreme HeatRisk.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...
Today could shape up to be another somewhat busy monsoon day, but
unlike last Wednesday moisture and the amount of instability will
be more limited. Atmospheric conditions at the moment are not
very conducive for convection due to the limited moisture, but the
upper levels are somewhat favorable for development. The
subtropical high has shifted far enough to the east (eastern New
Mexico/western Texas) to decrease the subsidence inversion. An
upper level trough has also moved in along the West Coast placing
much of our region within or near the more favorable right
entrance region of a weak upper jet. So, despite the overall
meager moisture currently in place, other atmospheric ingredients
are more favorable and better moisture is expected to advect
northward today potentially putting southern and central Arizona
back in the game for monsoon storms.

Given the anticipated scenario for late this afternoon and
evening, we are becoming more confident in our chances for
isolated to scattered thunderstorms. Part of this confidence comes
from the 06Z HRRR which shows storms developing north of Phoenix
and over Pima County late this afternoon with both clusters
sending outflows toward the Phoenix metro. With forecast MUCAPEs
near 1000 J/kg and CIN falling to below 100 J/kg late this
afternoon, any decent outflow collision seems likely to spark off
additional storm development. The 06Z HRRR shows this exact
progression with storms developing over or near the Phoenix metro
early this evening. Additionally, since moisture will be more
limited, DCAPEs will be very high (1700-2000 J/kg) supporting
strong to locally severe wind gusts. Forecast PoPs have been
raised into a 20-30% range, which better matches the latest high-
res guidance.

Convective chances for Monday are even more uncertain as guidance
generally shows at most a 10% chance despite moisture and
instability being better than today. However, subsidence will be
much stronger on Monday as the subtropical ridge begins to move
westward back into our region. We will have to wait until tonight
to have a better idea on the storm potential for Monday, but it
does seem to be considerably lower than this afternoon/evening.

Temperatures today will again be right near record highs with
lower desert readings from 110-115 degrees. The increased boundary
layer moisture expected for Monday should hold daytime highs down
a bit with NBM forecast highs currently between 106-111 degrees,
but heat indices will mostly match what are expected today.

&&

.LONG TERM /TUESDAY THROUGH SATURDAY/...
Forecast attention turns away from monsoon storm potential and
back toward the extreme heat conditions starting Tuesday. The
subtropical high center will continue to shift westward into our
region into the middle part of the week with the center likely
settling somewhere over southern Arizona from Wednesday through at
least Friday or Saturday. Forecast H5 heights are also shown to
reach 594-597dm for the latter half of the week which places it
just shy of climatological records for late August. NBM
temperature guidance remains quite consistent showing highs rising
into a 112-116 degree range for the latter half of this week as
conditions dry out. Daily temperature records in Phoenix will
continue to be in jeopardy through the entire week, but are likely
to fall short in Yuma and El Centro. Once the high center moves
overhead by Wednesday, rain chances will essentially go to 5% or
less. As of now, conditions for any monsoon storm activity do not
look good through next weekend.

&&

.AVIATION...Updated at 1800Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:

The potential for multiple outflow boundaries resulting in sudden,
gusty wind shifts this evening, as well as SHRA/TSRA developing in
the Phoenix Airspace presents the greatest weather issue during
this TAF period. Winds will favor E/SE late this morning followed
likely by a period of VRB winds before shifting out of a
prevailing westerly direction by 20-22Z this afternoon. TS over
the northern and eastern AZ high terrain are likely to send a
first outflow towards the lower elevations late this
afternoon/early this evening, which would cause a sudden wind
shift out of a N/NE`rly direction. A cluster of strong storms is
then expected to develop over western Pima, southwestern Pinal,
and/or southern Maricopa Counties this evening, which would
likely send a second, stronger outflow across the terminals from
the S/SW. This second outflow may cause temporary surface VIS
restrictions due to blowing dust and more prolonged slantwise VIS
issues if rain does not follow. Chances for SHRA/TSRA remain
around 20-30% across the terminals this evening, and so have
included this in PROB30 groups between 04-07Z. The wind forecast
is very low confidence this evening into the overnight hours due
to the possible influence of multiple outflows, and gusty, erratic
winds are expected if SHRA/TSRA develop near the terminals. Cloud
bases will remain mostly above 10 kft AGL through the period.

Southeast California/Southwest Arizona including KIPL and KBLH:

No major aviation concerns are expected through the next 24 hours.
Winds at KIPL will favor southeasterly directions. TS activity
over the Baja spine may send an southwesterly outflow into KIPL by
the late afternoon hours, with a less than 20% chance for direct
TS impacts. KBLH will swing between south to SW`rly winds, with
occasional gusts to around 20 kts. There is also a low chance
(less than 10%) for SHRA/TSRA conditions at KBLH, particularly
during the overnight period. FEW-SCT mid and high level cloud
decks will be common through the period.


&&

.FIRE WEATHER...
Hot temperatures will prevail through the entire week with shower
thunderstorm chances mainly today and possibly Monday. Strong
gusty winds will be possible late this afternoon and evening with
any thunderstorms, while chances for wetting rains will remain
below 20%. Minimum RHs will improve through Monday with readings
of 15-25% today and 20-30% Monday, before dropping back into the
teens into the middle part of the week. Temperatures will be
around 5-10 degrees above normal, with lower desert highs
eclipsing 110 degrees nearly every afternoon. 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 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
Aug 29   116 in 2023    117 in 1954    117 in 2005

&&

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

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

&&

$$

SHORT TERM...Kuhlman
LONG TERM...Kuhlman
AVIATION...Whittock
FIRE WEATHER...Kuhlman
CLIMATE...18/Kuhlman