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FXUS65 KPSR 041135
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
435 AM MST Fri Jul 4 2025


.UPDATE...Updated 12z Aviation Discussion...

&&

.KEY MESSAGES...

- Dry, along with cooler-than-normal, conditions are expected for
  the 4th of July.

- Temperatures warm through the remainder of the weekend, with
  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/...
Morning WV imagery and 500mb analysis reveals drier air spreading
across the Desert Southwest as the region sits between troughing
over California and building high pressure over Texas and Northern
Mexico. With this setup in place, the 4th of July is shaping up to
be quite nice, with near to slightly below normal regional
temperatures and virtually zero chances of showers and thunderstorms
for most of the forecast area. 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%.

The aforementioned high pressure 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 1125Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major aviation weather concerns under mostly clear skies are
expected throughout the TAF period. The overall wind pattern will
exhibit the more typical diurnal tendencies with easterly winds
this morning shifting out of the west by the late morning hours
with the west winds persisting well into the overnight hours. Wind
speeds will generally remaining aob 10 kts, although some
occasional afternoon/evening wind gusts in the mid to upper teens
will be possible.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns under clear skies are expected
throughout the TAF period. At KIPL, southeast winds will prevail
through this afternoon with a period of westerly winds expected
this evening. At KBLH, winds will generally persist out of a
southerly direction throughout the period. Speeds at KIPL will
remain aob 10 kts while at KBLH, wind gusts upwards of 20-25 kts
will be common throughout the day, diminishing this evening.

&&

.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...RW
LONG TERM...RW
AVIATION...Lojero
FIRE WEATHER...RW