964
FXUS65 KPSR 180727
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1227 AM MST Sat Oct 18 2025

.KEY MESSAGES...

- Dry and tranquil weather conditions will persist this weekend
  with temperatures back into the normal range.

- Temperatures will warm a bit further early next week with lower
  desert highs topping out around 90 degrees before cooling back
  into the normal range later in the week.

- A passing weather system during the middle of next week may
  bring some light shower activity focused over the Arizona high
  terrain; otherwise dry conditions will continue next week.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...
Upper level ridging is beginning to take over across the Desert
Southwest as a shortwave trough exits to the east and a cut-off
starts to take shape well to our southwest. Dry conditions will
continue over the next few days as the ridge is likely to stay in
place through at least Monday. H5 heights are forecast to rise
from the current 580dm to around 588dm by later on Monday leading
to a steady warming trend through Monday. NBM temperatures show
lower desert highs back into the normal range today (84-88
degrees) before peaking in the upper 80s to as warm as the lower
90s early next week. Overnight lows will also gradually creep
higher during the period with readings mostly in the 60s by
Tuesday and Wednesday morning. Other than the occasional passing
thin high clouds, skies will remain fairly clear through Monday.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
Little has changed with the expected evolution of the cut-off low
as guidance keeps it near stationary roughly 600-700 miles
southwest of San Diego through Monday night before beginning to
shift toward the northeast on Tuesday. As the system does
approach our region Tuesday into Wednesday, southerly flow should
increase allowing for at least a brief 12-18 hour window of
moisture advection into Arizona. PWATs are likely to increase from
0.3-0.4" on Monday to around 0.7-0.8" later Tuesday and Tuesday
night focused across south-central and southeast Arizona. The
moisture increase is notable, but the best forcing is likely to
stay over southern California and western Arizona where the air
will be much drier. Guidance is still showing some very modest
chances for showers and light accumulations across the Arizona
high terrain later Tuesday through a good portion of Wednesday
afternoon, but it should be far from any impactful weather. NBM
PoPs have actually gone down a bit from yesterday with only 10-15%
chances across the high terrain just to the north and east of
Phoenix and 5-10% chances into Phoenix. The cut-off low should
then exit to the northeast of the region by early Thursday leaving
a couple days of fairly zonal flow.

Temperatures are expected to take a slight dip as the cut-off low
enters our region starting Wednesday with lower desert highs
likely falling back closer to 85 degrees. After the passage of the
system, highs should drift back upward again by next weekend with
upper 80s a good possibility by Friday or Saturday of next week.

&&

.AVIATION...Updated at 0450Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns are anticipated through the TAF
period. Winds across the Phoenix area terminals will follow
diurnal tendencies with extended periods of light and variable to
at times calm conditions. Winds at KIPL and KBLH will be light and
variable with speeds under 5 kt through the period. Skies will be
mostly clear with FEW-SCT high level clouds moving in tomorrow
afternoon.

&&

.FIRE WEATHER...
High pressure will take a stronger hold across the region this
weekend into early next week as temperatures gradually rise to a
few degrees above normal by Monday. Humidities will remain fairly
stable with MinRHs mostly between 15-20% across the lower deserts
to 20-25% for higher terrain areas. Light winds are also
anticipated through at least Monday with directions mostly
following common diurnal patterns. A mostly dry weather system is
then expected to pass through the region during the middle of next
week bringing chances for mostly higher terrain light showers.
The system should also boost humidities slightly while also
leading to a period of occasional breezy westerly conditions
focused on Wednesday.

&&

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

$$

SHORT TERM...Kuhlman
LONG TERM...Kuhlman
AVIATION...Berislavich
FIRE WEATHER...Kuhlman

NWS Phoenix Office