816
FXUS65 KPSR 141735
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1035 AM MST Mon Sep 14 2026

.UPDATE...18Z Aviation Discussion

&&

.KEY MESSAGES...

- Abundant moisture will remain situated across the eastern half
  of Arizona providing enhanced chances for showers and
  thunderstorms through the middle portion of the week, especially
  over the mountain locations.

- There will be the potential for some storms to produce strong
  winds, but the bigger threats will be heavy rainfall and
  localized flash flooding over the next few days.

- Near to slightly above normal temperatures are expected
  throughout the entire week.

&&

.SHORT TERM /Today through Wednesday/...
The next few days should be fairly active with periods of showers
and thunderstorms and an increased threat of heavy rainfall and
flash flooding. Current objective analysis shows the subtropical
ridge now planted over the Lower MS River Valley while a deep
Pacific trough is moving through the Northern Rockies/Southwest
Canada. This places our region within a somewhat drier
southwesterly upper level flow, but southerly moist low and mid
level flow. So, despite the drier air aloft that is coming in from
the west, the low and mid level moist advection is keeping PWATs
anywhere from 1.4-1.8" across south-central into eastern Arizona.
Surface dew points well into the 60s and low level mixing ratios
between 12-14 g/kg are anticipated to last for another 2-3 days as
the synoptic pattern will largely remain unchanged.

Current satellite and radar imagery shows a decaying complex of
showers and storms across southwest New Mexico and southeast
Arizona. To the west across south-central Arizona, the moist
southerly flow is beginning to show some CU development across the
Phoenix area into the central Arizona high terrain. CAMs suggest
some scattered showers and isolated thunderstorms are likely to
develop over the next few hours somewhere across Maricopa into
Gila County. This convection should stay elevated with the only
threat being localized heavy rainfall before diminishing by mid
morning.

The rest of today should provide plenty of sunshine to further
build instability with HREF MUCAPEs reaching 1000-1500 J/kg from
Phoenix eastward by mid afternoon. However, just like yesterday
convection is not quite expected to fully utilize the instability
as the upper levels will remain fairly neutral with the best jet
support across New Mexico and southeast Arizona. CAMs do indicate
good convective development across southeast Arizona during the
latter half of the afternoon with more isolated potential into the
south-central Arizona lower deserts. The expectation for late
this afternoon into the evening is for better chances over the
high terrain east and southeast of Phoenix with PoPs of 30-50% and
a 15-25% chance into the lower deserts. Forecast soundings
indicate nearly uncapped environment late in the afternoon and
marginal DCAPEs which could result in a few strong wind gusts. The
biggest threat for today is likely to be heavy rainfall and
potentially a localized threat of flash flooding across eastern
Pinal into southern Gila County.

After an expected break in the action later this evening into the
early overnight, CAMs show another likely round of showers and
storms developing at any point after 3 AM Tuesday morning with the
best area of focus over the high terrain just northeast of
Phoenix. This area may need a Flood Watch for Tuesday morning as
the HREF is showing a bullseye of over 1" average QPF across
northeast Maricopa County.

As upper level support increases on Tuesday and likely peaks
during the first half of Wednesday, we are likely to have off and
on scattered showers and storms anywhere across south-central and
eastern Arizona. The latest CAMs indicate one round of storms
Tuesday afternoon initiating somewhere south and southeast of the
Phoenix area before spreading north northeastward into the evening
hours. The main forecast concern for Tuesday and especially into
Wednesday will be the periods of showers and storms supporting a
marginal to a slight risk of excessive rainfall potentially
leading to localized flash flooding. Moisture will remain
plentiful and at least modest instability will support scattered
thunderstorm activity into Wednesday. A Flood Watch is likely to
be needed for portions of the area on Tuesday and Wednesday.

Elsewhere early this week, dry conditions will prevail across
southeast California and likely across most of southwest Arizona.
A dry line has already set up along the Lower CO River Valley and
it is expected to attempt to push farther into Yuma and La Paz
Counties at times through Wednesday. Although the CAMs do not show
any convection forming across far southwest Arizona, it would not
be impossible to get an isolated strong storm or two across La
Paz and/or Yuma Counties. Temperatures will continue to be
slightly above normal across the western deserts with highs
around 105 degrees, while more clouds and rain-induced cooling
should keep highs closer to 100 degrees across the south-central
Arizona lower deserts.

&&

.LONG TERM /Thursday through Sunday/...
Guidance is starting to agree on a quicker drying trend later this
week as the Pacific trough is favored to move farther into the
Great Basin and at least into northern and western portions of the
Desert Southwest. This is likely to push drier air eastward
through most if not all of Arizona as early as Thursday but more
so Friday into Saturday. Thursday is still a bit of an uncertain
day as rain chances may still linger across the south-central
lower deserts and definitely over eastern Arizona. However, by
Friday, enough dry air moving in should end chances over the
lower deserts and really limit chances over the high terrain. It
is doubtful we will completely scour out all of the moisture
across the higher terrain, so 10-20% PoPs remain each day across
eastern Gila County through the weekend.

As conditions dry out into the weekend, temperatures are likely
to face a bit of a warming trend but as of now the region is
favored to stay under broad upper level troughing into the
weekend. Lower desert highs are expected to warm to above normal
by Friday or Saturday, but so far the NBM indicates a most likely
range of 103-107 degrees.

&&

.AVIATION...Updated at 1735Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:

The main impact will be periods of VCSH/VCTS, and SHRA/TSRA later
this afternoon (00-04Z) and once again tomorrow morning (10-14Z).
Confidence remains low as early morning models had a similar
outlook this morning, with nothing developing as expected. However,
the environment looks more favorable over the next couple of days
but monitoring and updates will need to follow. SHRA/TSRA will be
capable of producing locally gusty winds with a low chance
(10-20%) for gusts >30 kts. A period of southerly cross winds will
give way to westerly flow by this afternoon (21-22Z) then back
E/SE tonight. Wind speeds will mostly stay under 10 kts, outside
of shower and storm influences. SCT to occasionally BKN cloud
decks around 8-10K ft AGL will be common through the TAF period.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns will exist through the TAF period
under mostly clear skies. Winds will continue to behave similar
to the past 24 hours varying between southeasterly and westerly at
KIPL and southerly to southwesterly at KBLH with periods gusts
between 20-25 kts this afternoon.

&&

.FIRE WEATHER...
Periods of scattered showers and thunderstorms are likely through
Wednesday across the eastern districts supporting a localized
heavy rainfall threat. Moisture levels will remain elevated except
for southeast California. Expect minimum humidity levels to still
fall into a 15-25% range for the western districts while the
eastern districts will only dip to 30-45% through Wednesday.
Winds will generally follow diurnal patterns across the eastern
districts, while much of the western districts will have elevated
southerly winds with occasional gusts above 20 mph. By Thursday
into Friday, much drier air is forecast to spread eastward across
the region, eventually ending rain chances for all but the far
eastern Arizona high terrain and lowering humidities into the
teens across the lower deserts.

&&

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

$$

SHORT TERM...Kuhlman
LONG TERM...Kuhlman
AVIATION...Ryan
FIRE WEATHER...Kuhlman