388
FXUS65 KPSR 050949
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
249 AM MST Sat Jul 5 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 close to 115 degrees for some
  lower desert locations.

- Extreme Heat Watches have been posted for the Phoenix metro,
  along with surrounding areas of Maricopa and Pinal Counties,
  for Tuesday through Thursday

&&

.SHORT TERM /TODAY THROUGH SUNDAY/...
Morning atmospheric analysis reveals sub-tropical ridging now
encompassing much of the Desert Southwest and Northern Mexico, while
a few disturbances pass well to our north. This area of high
pressure will become the dominant weather regime for our region
over the next several days as it continues to build and migrate
further west In its current stage, with heights aloft between
592-594dm, day-to-day temperatures compared to yesterday will be
a few degrees warmer, but hover right around seasonal levels.
Highs across the lower deserts this afternoon are expected to
range between 101-109 degrees.

Model guidance does bring a quick developing area of low pressure
just off the California Coast over the weekend, which could inhibit
the progression of the ridge ever so slightly, and perhaps even
lower heights aloft into Sunday. Typically, when heights remain
steady or drop slightly, this translates to a similar trend in
day-to- day temps, but in this case, afternoon highs for Sunday
are forecasted to rise to between 106-111 degrees for the lower
deserts. The reason for this can be found in the trends of our
regional 850mb temperatures, as they are forecasted to increase
from today into Sunday.

Moisture content this weekend will be lacking, and it does not
appear a better influx can expected as we remain under unfavorable
flow aloft. This will largely keep any monsoonal related shower and
thunderstorms at bay through the rest of the weekend, except down in
southeast Arizona, where better moisture is available. However,
Hi- res guidance does hint as some short-lived activity along the
Maricopa, Pima County border, but chances are slight at best (10-
30%).

&&

.LONG TERM /MONDAY THROUGH FRIDAY/...
Looking beyond toward the upcoming week, the aforementioned ridge
will continue to build and eventually park itself over Arizona and
southeast California. With heights aloft projected to climb to 597-
599dm, temperatures will continue their upward climb, with most
lower desert locations ranging between 108-116 degrees through most,
if not all of the work week. Tuesday through Thursday looks to be
the hottest period as the ridge peaks in strength and sits virtually
right on top of our CWA. MaxT values of 110-116 will be common for
the lower elevations, translating to areas of Major HeatRisk. In
turn, an Extreme Heat Watch has been issued for the Phoenix
metro, and the surrounding areas of Maricopa and northern Pinal
Counties for the above-mentioned timeframe. Additional Extreme
Heat Products will likely be needed in the next 12-24 hours for
areas in Southwestern Arizona and Southeastern California. It
would also not be surprising, depending on subtle forecast shifts,
if products for some areas are extended into Friday, but
uncertainty regarding strength and positioning of the high will
delay that decision at least for a few more days.

For the fans of monsoon rainfall, you may want to look away. Due to
the expected subsidence aloft and the continuation of unfavorable
flow, rain chances will be limited to far Southeastern Arizona
through the end of the work week. Confidence is high that most of
the region will remain dry through this period, with very few (if
any) ensemble members showing measurable rainfall through Friday.

&&

.AVIATION...Updated at 0520Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major weather issues will exist through Saturday night under a
few, occasional mid/high cloud decks. Overnight wind directions will
be the greatest forecast uncertainty 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 issues will exist through Saturday night 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
be less evident in time and magnitude.

&&

.FIRE WEATHER...
Temperatures continue their warming trend toward above normal
levels through the remainder of the weekend as high pressure
builds overhead. Relatively high moisture across the eastern
districts will translate to MinRHs between 15-25%, but further
west, values will range closer to 10-15%. Those lower values
become more common across the region as drier spreads further
east. Overnight recoveries will only offer marginal relief, as
MaxRHs hover between 20-45% over the next several days. Winds will
follow familiar diurnal trends, with typical afternoon breeziness.
Rain chances will be confined to high terrain areas of the far
eastern districts, but CWR are <10%.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Watch from Tuesday morning through Thursday evening
     for AZZ534-537>540-542>544-546-548-550-551-553>555-559.

CA...None.
&&

$$

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