955
FXUS65 KPSR 262326
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
426 PM MST Sat Jul 26 2025

.UPDATE...Updated 00Z Aviation Discussion.

&&

.KEY MESSAGES...

- Near normal temperatures will warm to slightly above normal by
  the beginning of next week, resulting in widespread Moderate
  HeatRisk.

- Very dry conditions will greatly inhibit any rain chances
  through the weekend.

- Monsoonal activity should increase again across portions of
  Arizona region by the middle of next week.

&&

.SHORT TERM /Today through Sunday/...
Broad upper level troughing remains situated over the northeastern
Pacific and extending into the Western US, with an embedded
shortwave evident in mid-level wv imagery early this afternoon
over Central CA and moving into Western NV. Meanwhile, a
subtropical high is currently parked over the Southeast US, too
far east to influence the flow aloft over AZ. This unusual late
July setup has resulted in persistent, dry, southwesterly flow
over the region, scouring out available moisture and eliminating
rain chances across the entire state today. In fact, NAEFS/EPS
mean PWATS today into the first half of Sunday are generally below
0.5" across AZ, representing values below the 10th percentile and
in some places below the 2nd percentile of climatology for this
time of year. Another consequence of the proximity of the trough
to our northwest is a moderating of heights aloft, resulting in
near normal temperatures (even slightly below normal further
west this afternoon.)

By Sunday, ensembles show heights aloft gradually building from
the east as the subtropical high begins to shift westward.
As this occurs, anticyclonic flow will begin to impinge on the
eastern/southeastern portion of the state, reintroducing enough
moisture for perhaps a few isolated showers/weak storms to
develop. However, the forecast area will remain completely dry,
with near zero PoPs through the remainder of the weekend. The
primary sensible weather impact of this gradual pattern evolution
starting Sunday will be increasing temperatures. Daytime highs
are expected to reach near the 110 degree mark in the Phoenix area
to 105-108 degrees across the western lower deserts.

&&

.LONG TERM /Monday through Friday/...
The first part of next week will see the trough to our northwest
gradually weaken and likely lift a bit more to the north. As we
begin to somewhat lose the dry westerly flow influence from this
trough, the subtropical ridge is forecast to continue to
retrograde westward. Previous guidance was fairly confident in a
meaningful inverted trough moving out of northern Mexico and
reaching southeast Arizona later Monday into Tuesday. This is
still somewhat the case in the latest model runs, but the inverted
trough looks weaker and now is likely to get held up, not
reaching past southeast Arizona.

The slight shift in the flow pattern should still allow for a
period of southeast semi-moist flow into much of Arizona starting
Monday, but the recent model shift now mostly keeps the better
quality moisture across eastern Arizona through Tuesday. Very
limited shower and thunderstorm chances will be possible across
the eastern Arizona high terrain on Monday with slightly better
chances on Tuesday, but still mostly relegated to the higher
terrain. The flow pattern is not likely to change much going
through the middle of next week and this should provide for daily
chances for higher terrain convection and eventually increasing
moisture into the south-central Arizona lower deserts via
outflows. Guidance does try to indicate just enough moisture
working as far west as the Phoenix area to provide for some very
limited (10-15%) chances by next Wednesday. These daily low end
rain chances may very well continue through the rest of next week
as ensemble output shows little change in the positioning of the
subtropical high to our east and the broad troughing to our
northwest.

Temperatures next week look quite stable with H5 heights mostly
hovering within the higher end of the normal range. This should
keep daily highs right around or maybe 2-3 degrees above normal
throughout the entire week. The increased moisture and clouds
should also lead to higher overnight lows across south-central
and eastern Arizona with readings within the Phoenix metro mostly
between 83-88 degrees each night. Lower humidities and generally
clear skies across the western deserts should provide for
overnight lows mostly in the mid 70s to lower 80s.

&&

.AVIATION...Updated at 2325Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Winds will follow typical diurnal trends through the TAF period,
with speeds mostly at or below 10 kts and some afternoon gusts up
to 15-20 kts, with a brief period of S`rly winds near noon
tomorrow. High cloud decks will become SCT this evening through
tomorrow. No slantwise visibility impacts expected.

Southeast California/Southwest Arizona including KIPL and KBLH:
Winds at KIPL will predominantly favor the west while at KBLH
winds will generally be out of the south to southwest. Wind gusts
upwards of 20-25 kts are expected at both terminals this afternoon
and evening. There is around a 20% chance winds exceed 30 kts at
KIPL this evening for a couple hours. Near the end of the TAF
period, S to SSW winds are expected at both terminals.

&&

.FIRE WEATHER...
Very dry conditions with zero rain chances and near to slightly
above normal temperatures will continue through the weekend. Some
lower desert location may reach 110 degrees starting Sunday before
moisture increases gradually across the eastern districts next
week. MinRHs through Monday will be in the 5-10% range across the
lower deserts with poor overnight recoveries of only 15-35%.
Winds will tend to follow their typical diurnal tendencies with
some afternoon upslope gustiness. With the increase in moisture
next week there will also be increasing shower and storm chances
across the eastern districts, especially later in the week.

&&

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

$$

SHORT TERM...Whittock
LONG TERM...Kuhlman
AVIATION...Ryan/Benedict
FIRE WEATHER...Kuhlman