520
FXUS65 KPSR 042310
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
410 PM MST Fri Jul 4 2025

.KEY MESSAGES...

- Temperatures warm through the remainder of the weekend with lower
elevation highs hovering around 110 degrees by Sunday, resulting in
widespread Moderate HeatRisk.

- Further warming, and generally dry conditions, are expected into
next week with highs pushing near 115 degrees for lower desert
locations.

&&

.SHORT TERM /TODAY THROUGH SUNDAY/...
Afternoon showers and storms are firing off in southeastern Arizona,
but will remain well south of the region today, as much drier air
behind the decaying trough has a firm grip over western and central
Arizona. The exceptions to this will be around enhanced terrain
features of far southeastern Gila and Maricopa Counties, where some
very weak and short-lived showers may pop, but chances for these
areas max out at around only 20%.Temperatures this afternoon will
reach into the lower to mid-100`s across the lower deserts, with
evening temperatures cooling into the mid to upper 90s.

Building high pressure over Texas and Northern Mexico is projected
to strengthen over the remainder of the weekend, helping to nudge
the Pacific Low off to our west further north. This will translate
to warming temperatures during this timeframe, with afternoon highs
hovering near 110 degrees once again by Sunday. Global models do
indicate another Pacific Low developing just off the California
Coast by late Saturday, which presents an opportunity for a limit on
how far the region warms up. However, by that point, the sub-
tropical high will be the dominant feature and will help to stave
off any further advance eastward of this follow-on disturbance,
keeping us on an upward temperature trajectory. In terms of
rainfall, the strengthening high and a relatively unimpressive
moisture profile should suppress the development of convection for
most, if not all, of the region. Only chances (20%) will be once
again focused around high terrain areas.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Exiting the weekend, the sub-tropical high is expected to continue
its westward migration while continuing to strengthen, resulting in
a persistent warming trend into the start of next week. It appears
that ensemble guidance has come into better agreement regarding
where this ridge will setup and how far temperatures will rise.
Previous runs had depicted discrepancies between the GFS and EPS,
with the latter leaning drier and hotter. Well, it appears the GFS
is now trending toward that drier and hotter solution. Heights aloft
will push toward 597dm, translating to temperatures at the surface
between 108-116 degrees through the middle portion of the week. In
turn, areas of Major HeatRisk begin to develop as early as Monday,
becoming more widespread by Wednesday. With increasing confidence
and coverage of Major HeatRisk, Extreme Heat Products are likely to
be issued over the next 12 to 24 hours. Along as the high sits
directly overhead, and we do not see a better of influx of moisture,
which does not appear will be the case, convection is likely to be
suppressed across the vast majority of the region through at least
the middle of next week, except the typical high terrain spots of
eastern Arizona.

&&

.AVIATION...Updated at 2310Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major weather concerns will exist through Saturday afternoon
under a few mid/high cloud decks. Uncertainty in overnight wind
directions will be the greatest forecast challenge as some terminals
may not truly complete an easterly switch overnight, rather staying
variable through the morning hours. Confidence is good that a
westerly component will settle across the area Saturday afternoon
with limited gustiness.


Southeast California/Southwest Arizona including KIPL and KBLH:
No weather concerns will exist through Saturday afternoon under
clear skies. Confidence is very good that trends in wind speeds and
directions will be similar to the past 24 hours, though gusts will
likely be less pronounced.

&&

.FIRE WEATHER...
Near to below-normal temperatures will persist into the start of
the weekend, with above-normal readings returning by Sunday. Some
lingering moisture will result in relatively elevated MinRH  values
with readings between 20-25% in the eastern districts and 15-20% in
the western zones. Overnight recoveries Friday night will offer some
decent relief as readings hover between 40-60%. However, drier air
will lead RH values on a quick decline as daily minimums fall to 10-
15% by Sunday. As expected, MaxRHs will follow a similar drying
trend. Diurnal wind trends can be anticipated, with typical
afternoon breeziness. Rainfall activity over the next several days
will be quite limited, with only minimal chances (<10%) of wetting
rains over the eastern districts.

&&

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

&&

$$

SHORT TERM...Young/RW
LONG TERM...RW
AVIATION...18
FIRE WEATHER...RW