514
FXUS65 KPSR 131729
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1029 AM MST Sun Jul 13 2025

.UPDATE...Updated 18Z 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 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 1110Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
Periods of thick, elevated smoke creating slantwise visibility
issues will be the primary weather impact through Monday morning.
While surface visibilities will not be affected, slantwise
concerns will be maximized near sunrise/sunset times. Otherwise,
confidence is very good that winds will follow the same trend seen
over the past 24 hours, with gusty winds (15-20kts) this afternoon
and light and VRB by tomorrow morning.

Southeast California/Southwest Arizona including KIPL and KBLH:
No significant weather issues will exist through Monday morning under
clear skies. Wind trends will be very similar to the past 24 hours
with some form of a southerly component persisting, and only modest
afternoon/evening gustiness.

&&

.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...Ryan/18
FIRE WEATHER...18/Kuhlman