889
FXUS65 KPSR 250006
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
506 PM MST Thu Sep 24 2026

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- The chances for showers and thunderstorms will continue through
  tonight, with the highest potential mostly focused over the
  foothills and higher terrain areas north and east of Phoenix.

- After drying out temporarily this weekend, rain chances will
  return to the region late Sunday into early next week as
  tropical moisture gets pulled northward into the Desert
  Southwest.

- Near to slightly above normal temperatures will persist through
  the weekend before noticeably cooling early next week.

&&

.SHORT TERM /Today through Friday/...
An extensive area of showers and storms was ongoing through much
of the morning hours, especially to the south and west of the
Phoenix Metro Area across much of western Maricopa county
extending into portions of La Paz and Yuma Counties. All of this
activity was associated with a mid-level low currently spinning
over southern AZ. This activity should gradually weaken heading
into afternoon hours. The mid-level low is expected to move northward
into central AZ by this evening. However, despite there being
good ascent, the extensive cloud cover and rainfall activity from
earlier has overworked the atmosphere to the point that it is
likely that little to no activity, with the exception of portions
of Gila County, will materialize through the rest of this
afternoon through early this evening as depicted by the latest
runs of the hi-res guidance. By late this evening into the
overnight period, however, as the mid-level low migrates into
central AZ, the orographic and synoptic lift will combine to lead
to an area of showers and storms forming mostly across the
foothills and higher terrain areas to the north and east of
Phoenix with only isolated coverage across the lower deserts. As
the mid-level low lifts to the northeast on Friday, westerly flow
will encroach much of the region and advect much drier air,
essentially ending rain/storm chances.

Given the extensive cloud cover still in place, afternoon high
temperatures across the south-central AZ lower deserts, in
particular, are likely to struggle to reach 90 degrees with many
locations staying in the 80s. Across the western deserts, lesser
cloud cover with more sunshine will cause readings to top out in
the mid to upper 90s. Mostly clear skies on Friday should allow
temperatures across south-central AZ to rebound to more seasonal
levels, in the mid to upper 90s, with slightly warmer readings
into the lower 100s across the western deserts.

&&

.LONG TERM /Saturday through Wednesday/...
Dry westerly flow is expected to persist through at least
Saturday with large scale troughing remaining over the Pac NW
while the subtropical ridge slowly shifts southwestward from east
TX into the interior of MX. Due to the presence of the ridge to
our east, 500 mb hghts are expected to peak around 586-588 dam
Saturday afternoon. This will result in highs topping out between
100-105 degrees across the lower deserts (4-6 degrees above
normal) under mostly sunny skies and zero chance of rain. From
Sunday into early next week, there does look to be a significant
degree of cooling as tropical moisture arrives and rain chances
increase. Highs will likely fall below 100 degrees across the
lower deserts on Sunday and continue to cool to the upper 80s and
lower 90s Monday through Wednesday.

Our attention then turns to the tropical Pacific Sunday into early
next week where potential moisture from two weakening hurricanes
(Polo and Odalys) will come into play. There is still a high degree
of uncertainty as to a) how far north the residual moisture will be
shed out ahead of these decaying storms, and b) where the plume(s)
of moisture will set up. Another major question mark will be just
how deep and progressive a developing trough of low pressure will be
over the Intermountain West. All of these factors will have to line
up perfectly for our forecast area to get significant rainfall.
Both the GEFS and EPS are telling a different story with varying
degrees of moisture and timing and intensity of said trough which
is really complicating things. The latest NHC track for Hurricane
Polo shows the storm making landfall along the coast of the Baja
California by Monday which if aligned with the passage of the
aforementioned trough would draw a large plume of moisture into
interior MX and and much of AZ. NBM PoPs have already increased to
around 20-30% with an initial band of moisture on Sunday, but
with the main lift arriving on Monday, PoPs are now widespread
30-60% across our forecast area. The remnant tropical moisture may
linger into Tuesday before fully exiting the region on Wednesday.
It is also worth pointing out that some ensemble members are
showing significant rainfall totals in excess of 1-2" across
southcentral AZ Monday-Tuesday but there is still significant
spread between members. Therefore, we will likely have to wait
until this weekend for things to become more clear.

&&

.AVIATION...Updated at 0005Z.

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

Cloudy conditions with 6-12 kt westerly winds are expected
through the next few hours. Forecast confidence degrades heading
into the overnight hours. An area of low pressure will move
through tonight and may generate additional SHRA with embedded
TSRA, but confidence is low. Any rain development will likely
influence the wind directions. Otherwise, a NW-N wind component is
favored through the night. Any rain should dissipate and move off
to the east by 12-15Z Friday morning, after which conditions will
return to a more traditional diurnal tendency, with light winds
veering to W-SW in the afternoon. Brief CIGs down to 6K ft AGL are
possible in SHRA/TSRA, with mid and high CIGS more common through
the night. FEW to SCT cumulus around 7K ft AGL are expected
Friday afternoon.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather impact are expected during the next 24 hours.
A 5-10 kt SW wind is expected for the next few hours at KIPL
before turning VRB and light SE heading into Friday. At KBLH, a
SSW-SSE wind is favored through most of the period, with speeds
mostly 5-10 kts and periods of VRB. SCT to BKN skies will be
present over the region through early tonight, followed by clearer
skies heading into Friday.


&&

.FIRE WEATHER...
Widely scattered showers and thunderstorms will be possible
through tonight, mainly focused over the higher terrain of the
eastern districts. Localized gusty and erratic winds will be
possible in the vicinity of any storm that develops. Rain chances
will decrease Friday into this weekend before much better chances
for wetting rainfall arrives early next week. MinRHs will range
from 25-60% today with a gradual decrease to around 15-30%
region-wide Saturday. Significant moisture return is expected
across the eastern districts by Monday which will keep RH values
above 40% with excellent overnight recoveries. Winds will
generally follow diurnal patterns with speeds around 10-15 mph
with typical afternoon gusts in the upper teens.

&&

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

$$

SHORT TERM...Lojero
LONG TERM...Salerno
AVIATION...Benedict
FIRE WEATHER...Salerno/Lojero