643
FXUS65 KPSR 050908
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
208 AM MST Sun Oct 5 2025

.KEY MESSAGES...

- A gradual warming trend will begin today, with afternoon lower
  desert high temperatures returning to the middle 90s midweek
  and upper 90s to 100 degrees late week.

- Increasing rain chances late week into next weekend with a non-
  zero chance for impactful flooding rainfall possible, but
  forecast confidence remains low at this time.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...
Clear skies and dry conditions will continue to prevail over the
next few days as the region stays under a dry southwesterly flow
aloft. The region will largely be influenced by the subtropical
ridge situated to our east and southeast, while weak upper level
troughing remains positioned to our west into the Great Basin
area. Forecast thicknesses and H5 heights are shown to gradually
increase over the next several days and this will lead to a
noticeable warming trend. Daytime highs today are again expected
to mostly be in the upper 80s across the lower deserts, before
warming mostly into the lower 90s on Monday and mid 90s on
Tuesday. Overnight lows will remain fairly cool through Tuesday
morning with readings mostly in the upper 50s to mid 60s.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
Forecast uncertainty rises considerably during the latter half of
the week with guidance still showing at least some minimal
potential for heavy rainfall and impactful weather by next
weekend. Starting Wednesday, guidance is in very good agreement
showing decent mid-level moisture advecting into the area from
the east, eventually spreading through most of Arizona by
Thursday. This first batch of moisture is not likely to amount to
a whole lot as we are likely to still be under overall subsident
flow aloft and moisture in the low levels should remain fairly
limited. We should see increased clouds Wednesday into Thursday,
but rain chances are likely to be mostly limited to the Arizona
high terrain with PoPs still at most in a 10-20% range.
Temperatures during this time will also continue to warm up as the
subtropical ridge is likely to strengthen and nudge farther to
the west into our region. NBM forecast highs show readings across
the lower deserts in the mid 90s across southeast California to
the upper 90s across south-central Arizona.

Also occurring during the middle of the week, TC Priscilla is
forecast to continue to slowly track to the northwest staying to
the south and west of southern Baja. The latest NHC track has
Priscilla staying well west of Baja later this week with models
showing uncertainty with its track during its eventual
dissipation stage (likely on Thursday and Friday). The most likely
scenario has Priscilla staying west of Baja as it eventually
dissipates later this week, but we are still expected to see at
least some additional moisture advection into our region. This
moisture should eventually come into play as ensembles show a
deep Pacific low setting up off the Pacific Northwest at the same
time.

Model uncertainty is still too high to really have a good idea on
what will happen later this week into next weekend, but one
ingredient (moisture) is nearly certain to be in place. At some
point, the Pacific trough and an associated upper level jet is
likely to place our region within a fairly favorable area for
forcing for rainfall. How far south the trough and jet tracks is
still uncertain and it is definitely possible it will stay too
far to the north to really give our region much in the way of rain
chances. However, a stronger and more southerly track to the
trough may provide portions of our region with chances for heavier
precipitation by next weekend. NBM PoPs remain quite broad and on
the lower side (10-25%) from later Thursday through next weekend.
It may take several more days to have a good idea on how this
weather event will unfold.

&&

.AVIATION...Updated at 0440Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation weather concerns under clear skies are expected
throughout the TAF period. Winds will continue to exhibit the
typical diurnal tendencies with speeds aob 7 kts. There will
likely be extended periods of light variability, especially during
diurnal transitions.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns under clear skies are expected
throughout the TAF period. Winds will generally be light and
variable.

&&

.FIRE WEATHER...
Dry conditions with no chances for rain are expected through the
first half of the week. Temperatures will gradually warm during
the period reaching above normal by Tuesday. Expect light winds
through at least Tuesday, generally following diurnal patterns.
Daily MinRHs of 12-20% will continue through Wednesday, with
overnight recoveries of 30-50%. There should be increasing
chances for wetting rainfall by the end of the week, however,
better chances exist for next weekend and forecast confidence
remains low. However, there is at least high confidence that there
will be an increase in moisture by the end of next week pushing
minRHs into the 20-30% range with overnight recoveries of 45-65%.

&&

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

$$

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