210
FXUS65 KPSR 300515
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1015 PM MST Tue Sep 29 2026

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- Below normal temperatures will be common through the end of the
week across the eastern portion of the forecast area, while near
normal readings will return to the western deserts.

- Dry conditions will prevail from Thursday though at least early
next week as high pressure takes hold across the region.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY/...
Areas of light to moderate rainfall will continue across portions of
the region, mainly for Southern Gila, through this evening before
the majority of the shower and thunderstorm activity begins to push
of out of our forecast area. As expected, rainfall totals over the
past few days have varied greatly, with the driest spots seeing only
a few hundredths of an inch, while measurements upwards of 2-2.5"
have been seen so far in parts of south-central Arizona.
Accumulations will continue to rise for some areas, so it is not out
of the question that areas of 3+", mainly confined to foothill and
high terrain areas, will be seen once this is all said and done.

Even though most of the lower desert rainfall has moved on, it may
not be the last of shower and thunderstorm activity seen over these
areas. With drier air surging behind the main rain bands, noticeable
clearing has taken place across most of the region. This dry air
advection will not completely scour out boundary-layer moisture
which, combined with day-time heating, should promote the presence
of some decent CAPE upwards of 500-1000 J/kg. With the best ascent
associated with the low removed from our area at this point, any
convection that can pop will be heavily dependent on orographic
influences. A sharp gradient of 0-6km shear will be located
overhead, so maybe some longer lived cells are be observed, but the
majority should be short-lived due to lack of mid and upper-level
support/lift. Even with the environment, confidence in this round of
activity is fairly low as CAMs have been inconsistent run-to-run on
where it places these showers and storms, with some keeping them
within the Flagstaff CWA, while others show the Phoenix metro and
even areas as far south as the I-8 corridor seeing something form.
Nonetheless, the main impacts will be brief heavy downpours, gusty
winds, and perhaps some isolated instances of small hail if storms
can become strong enough.

Today should feel a bit like fall across the portions of the region
as high temperatures will run a good 15 degrees or so below normal
across south-central Arizona. Readings for the lower elevations will
run in the 70s and low 80s, while the higher elevations will
struggle to get out of the 60s. The further west you go, the warmer
it will be as Southwest Arizona and Southeast California will reach
into the middle 80s and lower 90s, which is still a good 4-8 degrees
below normal.

Wednesday will be a transition day as the Pacific low gradually
exits the region. Some morning scattered showers are likely to still
be across the far eastern Arizona high terrain, but any activity
should quickly wind down in the afternoon. Elsewhere on Wednesday,
sunny skies and warmer temperatures are forecast for southeast
California and southwest Arizona while the south-central Arizona
lower deserts will see some lingering clouds and a continuation of
well below normal temperatures.

&&

.LONG TERM /THURSDAY THROUGH WEDNESDAY/...
Model guidance shows upper level ridging fully moving into our
region on Thursday and likely staying put through the upcoming
weekend. This will lead to gradual drying and mostly clear skies
while temperatures slowly rise closer to the normal range for the
south-central Arizona lower deserts. The western lower deserts may
reach 100 degrees again starting Friday, but for the eastern half of
Arizona some reinforcing cooler air from the east Friday through
Saturday should keep daytime highs at or just above 90 degrees
through Saturday. This cooler easterly flow may even continue into
early next week with temperatures in the Phoenix area staying right
near seasonal normals for early October.

&&

.AVIATION...Updated at 0515Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major weather issues will exist through Wednesday evening under
periodic midlevel cloud decks, though uncertainty in wind shifts and
directions will be heightened this period. West winds should become
easterly by midnight, however variability may be common through the
overnight. Periodic 8-10K ft AGL cigs will sweep across the Phoenix
metro overnight, and an isold SHRA may be possible, though chances
and coverage are too low to include in this package. Very low
confidence exists regarding wind directions throughout the day
Wednesday as a low pressure system may sit directly on the Phoenix
metro creating a wide variety of directions, though speeds should
not be particularly strong.


Southeast California/Southwest Arizona including KIPL and KBLH:
No weather concerns will exist through Wednesday night under mostly
clear skies. Confidence is excellent that weakening W/NW winds will
become variable for a prolonged period during the day with a
tendency towards becoming southerly by Thursday.

&&

.FIRE WEATHER...
Widespread showers and isolated thunderstorms will affect much of
the area early today before mainly affecting the Arizona high
terrain this afternoon and evening. Moderate to heavy rainfall is
likely to impact the Arizona high terrain through at least early
afternoon. Humidities will begin to trend lower across the western
districts later today, but more so on Wednesday. Elevated humidities
will persist across the eastern districts through at least Thursday.
Winds will be breezy to locally windy at times today before becoming
light again on Wednesday. Drier conditions and near to slightly
above normal temperatures are forecast for later this week and
through the weekend.

&&

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

&&

$$

SHORT TERM...RW
LONG TERM...Kuhlman
AVIATION...18
FIRE WEATHER...Kuhlman