146
FXUS65 KPSR 300520
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1020 PM MST Fri Aug 29 2025

.UPDATE...06Z Aviation Discussion.

&&

.KEY MESSAGES...

- Temperatures for the Labor Day weekend will rise slightly above
  normal, leading to increasing widespread Moderate HeatRisk.

- Overall dry conditions will prevail through the weekend before rain
  chances gradually increase during the first half of next week.

&&

.SHORT TERM /Today through Sunday/...
We started off this morning with rumbles of thunder in some parts
of the Valley thanks to an outflow/gravity waves stemming from
convection down near the international border that acted upon
lingering mid-level moisture and instability. This allowed for
isolated to scattered showers and thunderstorms to develop across
central and eastern portions of the Valley, providing Phoenix Sky
Harbor with 0.01" while other areas saw upwards of around 0.25".
Drier conditions have since prevailed as dry westerly flow aloft
takes hold over the region, leading to mostly clear skies across
much of our area this afternoon as shown by the latest visible
satellite imagery.

Westerly flow aloft will persist into this weekend, allowing for
drier air to continue to be pulled into the region and dropping
PWATs near to below an inch. This will eliminate PoPs for most of
our area for the weekend outside of low end chances across the
southern Gila County high terrain by Sunday.

With drier conditions and plenty of sunshine prevailing across the
area this weekend, temperatures will rise slightly above normal for
the Labor Day weekend. NBM temperatures for Saturday show highs
topping out around 103-107 degrees across the lower deserts before
climbing to around 104-109 degrees Sunday. This will lead to
increasing widespread areas of Moderate HeatRisk for the holiday
weekend. If you have outdoor plans this weekend, be sure to stay
cool and hydrated.

&&

.LONG TERM /Monday through Thursday/...
As we turn our attention to next week, the overall synoptic
pattern will return to a more favorable pattern for monsoonal
activity with the high pressure being situated over the general
Four Corners Region, with easterly flow overhead. Guidance also
shows a potential inverted trough nearing or pushing into southern
AZ as early as Monday and potentially stalling out for a couple
of days proving some forcing for monsoonal activity. Monday may
end up being more of just a day for higher terrain activity with
outflow boundaries surviving into the lower deserts as the
atmosphere works to bring in better moisture (ensembles show PWATs
decreasing to 1" or less this weekend with westerly flow aloft)
across the lower deserts to support more showers and storms.
However, a few showers and storms would be possible if there were
multiple colliding outflow boundaries. PWATs will be on the rise
through the middle of next week with PWATs approaching 1.2-1.4"
range Tuesday and 1.3-1.6" range on Thursday. The EPS is running
about 0.2" higher PWATs than the GEFS. As for temperatures next
week, we look to cool off back below normal, especially if we have
showers/storms that move through and their associated cloud
cover. There are still a lot of unknowns for next week, but it
could shape up to be quite active if there is enough moisture
available.

&&

.AVIATION...Updated at 0520Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation concerns are anticipated through the forecast period.
Light westerly flow will continue for the next several hours, with
the exception of KIWA which should see an easterly shift around
09Z. Confidence is low for an easterly shift at KPHX Saturday
morning, but there may be a few hours of easterly winds between
12Z-16Z before returning out of the WSW by 17Z-18Z. Skies should
remain mostly clear aside from a few passing high clouds.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected through the forecast period
under mostly clear skies. Winds will be primarily W-NW at both
terminals overnight, becoming more N-NE at KBLH Saturday morning.
Speeds should remain aob 5 kts.

&&

.FIRE WEATHER...
Mostly dry conditions continue through the weekend with near 0%
chance of wetting rains. MinRHs today will mostly range between
15-20% this weekend. Winds will remain fairly light, with typical
afternoon breeziness, through the period while mostly following
typical diurnal trends. Temperatures this weekend will rise
slightly above normal with highs approaching 110 degrees for some
lower desert areas by Sunday. Chances for monsoonal activity will
increase again going into next week, with activity starting as
early as Sunday across the higher terrain in eastern Arizona.

&&

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

$$

SHORT TERM...Smith
LONG TERM...Berislavich
AVIATION...Salerno
FIRE WEATHER...Smith/Berislavich