896
FXUS65 KPSR 122325
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
425 PM MST Sat Jul 12 2025

.UPDATE...Updated Aviation Discussion

&&

.KEY MESSAGES...

- Temperatures will hover a few degrees above the daily normals
yielding widespread moderate HeatRisk through early next week before
cooling closer to the seasonal average during the latter half of the
week.

- Thunderstorm chances will slowly increase over eastern Arizona
higher terrain into early next week with chances and associated
impacts eventually descending into lower elevations by the middle of
the week.

&&

.SHORT TERM /Today through Sunday/...
High pressure centered near the southern California coast is
spreading dry northwesterly flow across the region keeping
convective activity at bay this afternoon. Convection firing atop
the White Mountains is remaining mostly anchored over the higher
peaks, thus anything more than a slight migration to the southwest
near the far eastern CWA border will be the extent of the activity
worth noting. Otherwise, clear skies and afternoon high
temperatures will be near or slightly above normal as lower desert
high range in the 105-110 range.

With the highest heights aloft shifting west, H5 values in a
592-595dm range will be common over the forecast area the next
several days; and numerical guidance spread remains very narrow
advertising readings 2F-4F above normal yielding widespread
moderate Heat Risk. The shallow moisture advected into lower
elevations yesterday (and to a lesser extent early this morning)
from a classic "Gulf surge" has been partially scoured/mixed such
that favorable 10 g/kg boundary layer mixing ratios have been
depressed mostly south of the international border. By Sunday, a
piece of the anti-cyclone will begin to build into southern UT
fostering better synoptic scale flow while marginally better
moisture profiles advect westward from New Mexico. HREF membership
suggests more concentrated thunderstorm activity blossoming over
E/SE Arizona which should induce better organized outflows, albeit
at a distance from the forecast area, but likely still favorable
towards importing a deeper mixed, higher theta-e airmass into the
CWA setting the stage for a typical progression of monsoon impacts
next week.

&&

.LONG TERM /Monday through Friday/...
During the first half of next week, subtropical ridging will
propagate back towards the four corners, however midtropospheric
heights should be further eroded by the combination of northern
stream jet energy in the Great Basin and a very distinct inverted
trough approaching through northern Mexico. Ensemble agreement is
actually quite good with respect to this evolution with uncertainty
primarily tied to the timing and exact location of the latter
mentioned inverted trough which could potentially materialize into a
slow moving closed low by the end of the week. During this synoptic
transition, deeper moisture profiles will slowly improve over the
region through both low level advection and midlevel residual
moisture shed from upstream convective complexes. Recent GFS BUFR
soundings suggest this moistening phase rather gradual with deep
boundary layer mixing ratios near 10 g/kg and total column PWATs
above 1.50" not settling over the CWA until Wednesday. Regardless,
this appears to align with a typical monsoon season progression
where mountain storms first send distant outflows into lower
elevations, then marginally moisture profiles support storms
beginning to encroach towards lower elevations with stronger
outflows and blowing dust impacts, and finally stronger, colliding
outflows sparking storms across a larger portion of the forecast
area. During this evolution, confidence is good that slightly above
normal temperatures early in the week will retreat close to the
seasonal normal by the middle of the week.

During the latter half of the week, the synoptic pattern should
become extremely favorable for both higher theta-e advection and
large scale ascent mechanisms. A large preponderance of model output
suggests the aforementioned inverted trough nearly stalling over
northern Sonora providing some vorticity forced ascent and a highly
divergent and optimal jet level wind profile. In fact, operational
models indicate an enhanced meridional jet developing over the CWA
which would encourage pronounced lift juxtaposed with plumes of
higher theta-e surging into Arizona. Whereas strong winds and
blowing dust would be the initial impacts early/midweek, this
pattern may evolve into one of a heavier rainfall/flash flooding
threat late in the week supported by deeper moisture profiles, warm
rain processes, and training rainfall scenarios. Forecast soundings
suggest an evolution towards more moist adiabatic thermal profiles
hitting a "sweet spot" of low level 12 g/kg mixing ratios, PWATS
1.50-1.75", and MUCape 500-1000 J/kg. Historically, these types of
synoptic and thermodynamic profiles have produced some of the larger
thunderstorm impacts for the forecast area. Interestingly, the 00Z
ECMWF is now producing a classic signal of possible morning storms
with a theta-e surge both Thursday and Friday indicative of strong
forced ascent. While these forecasts don`t always come to fruition,
this signal has occasionally been a precursor to some larger
convective and flash flood events around south-central Arizona, and
close attention will need to be paid to these days later next week.
Not surprisingly, temperature guidance spreads widen substantially
with the uncertainty of thunderstorm effects, however readings near
to slightly below normal should be common with the potential for any
morning/early afternoon storms to relegate readings below 100F in
some lower elevation communities.

&&

.AVIATION...Updated at 2325Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No aviation concerns are expected during the TAF period. Winds
will continue to follow diurnal trends with some occasional gusts
upwards of 20 kts through sunset. Much like the past few nights,
the typical early morning E`rly shift at KPHX appears uncertain
and may only last for a brief window if it were to occur. If not,
W`rly winds will persist. Besides a FEW mid-level clouds to the
north and east of the terminals, skies will be mostly clear.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected over the next 24 hours as
diurnal wind trends and clear skies prevail. Some occasional
gusts will be observed at each terminal this evening, but speeds
will be generally light otherwise.

&&

.FIRE WEATHER...
Above normal temperatures and primarily dry conditions will persist
through early next week before moisture increases and thunderstorms
chances blossom over higher terrain of eastern districts, then
eventually into lower elevation locations. Wetting rainfall chances
will initially be quite low with the greatest fire weather threat
being lightning with minimal rainfall amounts, however by the
middle of the week, more widespread storms with higher moisture
content will favor areas of beneficial rainfall, particularly in
higher elevations of eastern districts. Otherwise, minimum RH
levels will fall into a 10-20% range the next several days before
improving closer to a 15-30% range during the middle of next week.
Poor to fair overnight recovery of 20-50% will similarly improve
closer to a 30-70% range. Afternoon upslope gustiness 20-25 mph will
be common through the period with stronger thunderstorm outflow
winds becoming more prevalent next week.

&&

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

$$

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