838
FXUS65 KPSR 130952
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
252 AM MST Sun Jul 13 2025

.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 providing
for some isolated storms over the eastern high terrain. Low PoP
chances of mainly 10-20% is expected for this afternoon east of
the Phoenix area.

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 and
Southeast California/Southwest Arizona including KIPL and KBLH::

No major aviation concerns are expected during the TAF window.
Winds will follow typical diurnal trends, with some afternoon and
evening gusts near 20 kts later in the forecast period. The usual
switch to the east at KPHX early Sunday morning is still
uncertain, but if one were to occur, it will be short lived.
Otherwise, west winds will prevail at the terminal. Wildfire
smoke will create hazy skies across the region, but the majority
of it should remain suspended aloft. Some slantwise visibility
issues cannot be completely ruled out, however, surface VIS should
remain clear.

&&

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