952
FXUS65 KPSR 140510
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1010 PM MST Sun Jul 13 2025

.UPDATE...Updated Aviation Discussion

.KEY MESSAGES...

- Temperatures will continue hover a few degrees above the daily
normals early this week yielding widespread moderate HeatRisk before
cooling to around seasonal averages during the latter half of the
week.

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

&&

.SHORT TERM /Today through Monday/...
The subtropical high remains centered just off the coast of southern
California, while a shortwave trough is currently tracking south
southwestward through New Mexico. The high with H5 heights of 592-
594dm still parked over our area will provide for another day of
above normal highs today with readings around 110 degrees for the
majority of the lower deserts.

Farther east, better moisture is seen across New Mexico with some
of that moisture moving into southeast Arizona this afternoon.
Robust convection is currently firing along the Mogollon
Mountains in New Mexico and propagating to the southwest,
remaining south and east of the region. Here locally, low PoP
chances of mainly 10-20% is expected for this afternoon east of
the Phoenix area across higher terrain. While the current state of
convection would suggest a decreasing chance, we will have to
keep a close eye the evolution of these storms as they continue to
evolve later this afternoon and into this evening across
southeastern Arizona, as hi-res models are hinting at outflows
from the southeast possibly reaching northwestern Pinal County
into the overnight hours (generally 9 pm or later). The HRRR
continues to advertise this scenario, thus should robust outflows
reach this region, gusty winds up to 30-40 mph (HREF probabilities
still remain 10% or less for 35+ mph gusts) and blowing dust
could become problematic in the typical dust prone areas of Pinal
County. While impacts would remain limited with this scenario for
the Phoenix metro, cannot rule out hazy conditions setting in for
the overnight hours tonight. While there is some elevated
instability available, conditions are too dry (i.e. too much
inhibition) to reasonably think that thunderstorms could develop
along any outflow in Pinal County tonight.

Energy from this shortwave over New Mexico is then expected to track
southwestward into northern Mexico and Baja on Monday, while the
subtropical high shifts a bit farther to the west, imposing less
subsidence over our region. The moisture to our east and southeast
should also gradually begin to seep farther westward into south-
central Arizona on Monday. The weakening influence of high and the
slightly better moisture should allow for increased shower and
thunderstorm chances Monday afternoon and evening, but still with
the focus across the eastern Arizona high terrain. We can`t rule out
a couple showers or thunderstorms reaching the outskirts of the
Phoenix Metro Monday evening, but PoP chances are mostly below 15%.

&&

.LONG TERM /Tuesday through Saturday/...
The middle part of the coming week is looking quite good for monsoon
rain chances, largely due to a weak upper level trough/low
developing to our south by Tuesday and eventually slowly tracking
northward later in the week. This disturbance is seen forming over
Baja and the Gulf of California from the remnant energy from the
shortwave which is currently moving through New Mexico. The
subtropical high is also forecast to split with one high center
shifting westward over the Pacific and another center forming
somewhere around the Four Corners area by Wednesday. The flow
between the low to our south and the high to our northeast will in
turn shift out of the east southeast Tuesday into Wednesday allowing
better quality moisture to advect into our area.

For Tuesday, moisture is likely to still be a bit of a limiting
factor for shower and thunderstorm chances, while the developing
upper low to our south will just begin to present increasing forced
ascent into southern and central Arizona. Rain chances Tuesday are
still likely to be mostly confined to higher terrain areas, but PoPs
have increased to 10-20% into the Phoenix area by the evening.
Tuesday may also bring the chance for a few stronger storms over the
higher terrain, but as of now there are no clear signals for any
organized threat of strong storms. Although moisture will still be
somewhat limited Tuesday, a weak steering flow may pose a minor
threat for very localized heavy rainfall over the higher terrain of
eastern Arizona.

By Wednesday into Thursday, guidance is in good agreement showing an
increasingly organized upper level low centered just to our
southwest providing ample difluence aloft and forced ascent over the
eastern 2/3s of Arizona. Moisture advection should also be maximized
over southern and central Arizona during this time, but with the
GEFS and EPS still differing on how much moisture. The GEFS mean
PWATS currently show upwards of 1.5", while the EPS is closer to
1.8", centered over south-central Arizona. The EPS is also slightly
stronger with the upper level support. Despite the decent moisture
and upper level support, both model suites seem to be underplaying
the rainfall potential later this week. For now, guidance mostly
supports the highest NBM PoPs of 30-60% over south-central and
eastern Arizona falling from mid day Wednesday through Thursday
evening. It is still early to be able to nail down the details, but
we may see the first round of storms on Wednesday afternoon and
evening with the chance of a few strong to severe storms with winds
and heavy rainfall the main threats. As the event continues into
Thursday, the threat may transition to more of a heavy rainfall and
flood threat. We still have several days until this potential, so
forecast thinking very well could change. For now, WPC is
highlighting areas from Phoenix eastward in a Marginal Risk for
excessive rainfall.

Model uncertainty increases even more by Friday into next weekend as
there are differences with the eventual track of the upper low and
if it actually ejects north of our region or not. The GEFS mostly
favors the low stalling out over our region before dissipating
completely, while the EPS ejects the low to our northwest by
Saturday. If the EPS is correct, then we would likely see a big push
of dry air into our area, while the GEFS would mostly continue our
monsoon storm chances through next weekend. Either solution seems
plausible at this point in time with the NBM PoPs showing an overall
downtrend overall.

Temperatures going into the middle part of this week are expected to
cool off, especially over central and eastern Arizona where storm
activity is likely. NBM forecast temperatures quickly dip to a few
degrees below normal by Wednesday, but then begin turning hotter
again into next weekend as monsoon activity may begin to wain. H5
heights are also expected to increase later this week into next
weekend as the subtropical ridge restrengthens somewhere to our east
and northeast.

&&

.AVIATION...Updated at 0510Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
Periods of elevated smoke creating slantwise visibility issues
will be the primary weather impact through Monday evening,
especially around sunrise and sunset. Surface VIS should remain
unaffected. Winds will continue to follow diurnal trends, but the
usual E`rly shift at KPHX continues to remain an uncertainty.
However, a decaying outflow approaching from the SE may be what
throws winds back to the E overnight, but guidance has a longer-
than-usual period of VRB directions as this feature may fizzle out
right on top of the metro. Stronger outflow winds out of the E are
being hinted at for Monday evening, but too much uncertainty is
present to include mention in the TAFs at this time.

Southeast California/Southwest Arizona including KIPL and KBLH:
Periods of lofted smoke creating slantwise visibility issues will
continue to be the main aviation impact through Monday evening,
with those issues enhanced during the sunrise and sunset periods.
Some gusty winds out of the SE and S at KIPL and KBLH respectively
may develop early tonight, gusting around 25 kts, but this will
largely depend on far a wave feature propagates westward.
Otherwise, winds will follow familiar diurnal trends through the
period.

&&

.FIRE WEATHER...
Above normal temperatures and primarily dry conditions will persist
early this 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 across south-
central and eastern Arizona. Otherwise, minimum RH levels will fall
into a 10-20% range the next couple of days before improving closer
to a 15-30% range during the middle part of the 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 by mid week.

&&

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

$$

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