627
FXUS65 KPSR 281120
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
420 AM MST Thu Aug 28 2025

.UPDATE...Updated 12Z Aviation Discussion.

&&

.KEY MESSAGES...

- Cloudy skies and light shower activity will affect southeast
  California and portions of southwest Arizona today with fairly
  cloudy skies elsewhere.

- After the near to slightly below normal temperatures through
  Friday, conditions will turn hot again over the weekend with
  widespread Moderate Heat Risk developing.

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

&&

.SHORT TERM /Today through Friday/...
Drier air filtered throughout much of the area late Tuesday into
Wednesday, but in the past 12 hours or so mid and upper level
moisture has been streaming into southern California and now
portions of Arizona. This moisture was once associated with TC
Juliette centered west of central Baja, but the system has been
getting quickly sheared apart with the high level moisture getting
pulled northward with the help of the weakening Pacific trough
off the southern California coast. As this higher level moisture
continues to stream over the western deserts, we will see top down
saturation take place eventually allowing some light rain showers
to cover portions of southeast California and southwest Arizona
from around sunrise through this evening. Rainfall amounts are not
expected to amount to much with locations seeing a trace to maybe
a few hundredths of an inch. The cloud cover today will be quite
thick across the western deserts keeping temperatures well below
100 degrees, while some breaks in the clouds across the south-
central Arizona deserts should allow for highs at or just over 100
degrees.

Later tonight into Friday the moisture tap from the remnants of
Juliette will shut off and the drying conditions will again
commence. Friday is looking like we will see mostly sunny skies as
the subtropical high again takes over across the region. This will
boost temperatures out west to just above 100 degrees again with
similar readings in the Phoenix area.

&&

.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 1120Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No significant weather issues will exist through the TAF period
under BKN midlevel cigs that will start improving by the end of
the period. Light east (or variable) winds in this morning will
switch back to W/SW by noon. A late easterly shift is again
expected during the overnight/early morning hours Friday, and
winds may just go light and variable instead. Some occasional
virga will be possible today as solid cigs persist, no SHRA/TSRA
activity is expected.

Southeast California/Southwest Arizona including KIPL and KBLH:
Gusty W/NW winds today with widespread virga/SHRA will be the
greatest weather issue under persistent thick cigs around 10K ft
AGL. Virga/scattered -SHRA has spread into the area early this
morning. Gusts around 25-30kt will be prevalent by the mid-to-late
morning hours. KIPL will have the best chance for prolonged light
rain, gusty winds, and lowest cigs. Activity should begin clearing
the area late this afternoon/early this evening. Clouds will begin
to clear and lift during the overnight hours.

&&

.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 20-30% before gradually decreasing into the
teens by Saturday. 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...Kuhlman
LONG TERM...Kuhlman
AVIATION...Berislavich/18
FIRE WEATHER...Kuhlman

NWS Phoenix Office