264
FXUS65 KPSR 290505
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1005 PM MST Thu Aug 28 2025

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- After near to slightly below normal temperatures through Friday,
conditions will warm again over the weekend with widespread moderate
HeatRisk developing.

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

&&

.SHORT TERM /Today through Friday/...
Early afternoon WV imagery shows mid and upper level moisture
continuing to stream into southern California and parts of western
Arizona. This moisture stems from the remnants of TC Juliette, which
continues to advance inland toward the northeast. The forcing and
moisture from these remnants has led to continued light shower
activity across portions of southern California extending into
western portions of Arizona. Objective analysis show PWAT values
across the western CWA upwards of 1.5-1.8" with the 18Z Yuma
sounding showing most of this moisture residing above 700 mb and
minimal instability. Surface observations show only a couple of
locations across southeast California measuring any rainfall from
these very light showers. Light shower activity will continue
through the rest of the afternoon with some gusty winds possible at
times. The remnant tropical moisture will continue to exit to the
northeast this evening allowing for drier air to prevail tonight
into tomorrow. Drier conditions will persist through the end of the
week eliminating rain chances from the forecast. Drier conditions
and clearing skies will help boost temperatures across southeast
California and southwest Arizona Friday with forecast highs climbing
to around 100-105 degrees across the lower deserts Friday afternoon.

&&

.LONG TERM /Saturday through Wednesday/...
The boundary layer will noticeably dry out by Saturday as H5 heights
of 590-592dm remaining in place with the subtropical ridge
eventually repositioning itself over the Interior West on Sunday.
The drier surface conditions and continued mostly clear skies this
weekend will give a further boost to temperatures pushing daytime
highs between 102-106 degrees Saturday and 104-109 degrees Sunday.
The hotter temperatures this weekend will lead to widespread
Moderate HeatRisk.

As the ridge shifts northward into early next week, the flow around
the high center will allow for a return of east southeasterly flow
into southern and central Arizona by Monday. Guidance is also now
showing a potential inverted trough nearing or pushing into southern
Arizona as early as Monday and possibly stalling out for a couple
days providing some forcing for monsoon convection. Rain chances for
Monday and Tuesday have improved because of this potential
disturbance, but there is still some uncertainty, especially with
the amount of moisture that will work into our area. For now
guidance is showing only marginal amounts of moisture with PWATs
between 1.2-1.5". This would definitely be enough moisture for
higher terrain convection and outflows into the lower deserts, but
it might not be enough to trigger anything other than isolated
storms into the south-central lower deserts. This pattern could last
for a day or even 2-3 days before some additional drier air gets
pulled back into the area from the northeast and/or the inverted
trough dissipates. Looking out even further in time, both the GEFS
and EPS seem to be picking up on a better moisture return flow by
the following weekend, potentially associated with another tropical
system near or off the coast of Baja. 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 0505Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major weather concerns will exist through Friday night as
mid/upper level BKN cigs gradually scatter. Confidence is good that
winds will behave similarly to the past 24 hours with a later than
usual nocturnal wind shift, and periods of light and variable winds
Friday morning (possibly in lieu of a widespread easterly
component). Directions should revert to westerly by noon Friday with
limited wind gusts and nearly zero chances of thunderstorms and
associated impacts.


Southeast California/Southwest Arizona including KIPL and KBLH:
No significant weather issues will exist through Friday night as
thick 10-15K ft AGL cigs gradually clear the region. Confidence is
good that N/NW winds will prevail into the overnight before trending
towards a light and variable character by sunrise. Directions should
favor a S/SW component later Friday afternoon with limited
gustiness.

&&

.FIRE WEATHER...
Overall cloudy skies will prevail today with periods of very light
showers across the western districts. Drier conditions Friday and
into the weekend will lead to warmer temperatures and near 0% chance
of wetting rains. MinRHs over the next couple of days will mostly
range between 15-25%, falling into the teens for the weekend. Winds
will remain fairly light through the period mostly following typical
diurnal trends. Temperatures will remain near to slightly below
normal through Friday before rising to slightly above normal
starting Saturday. Chances for monsoonal activity will increase
again going into next week.

&&

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

&&

$$

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