619
FXUS65 KPSR 110610
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1110 PM MST Fri Oct 10 2025

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- A Flood Watch remains in effect for southeast CA and southwest
  AZ through this evening and for all of south-central AZ from
  this afternoon through Sunday.

- Multiple rounds of showers with occasional embedded
  thunderstorms will affect much of the area today through at
  least Sunday morning with the heaviest rainfall likely over
  higher terrain areas to the north and east of Phoenix. Some
  locations could receive rainfall totals exceeding 2.00" which
  will promote excessive runoff into area watersheds, leading to
  flooding of low lying areas.

- Additional chances for showers and thunderstorms are expected
  across primarily southeastern Arizona for Monday, but still with
  slight chances in south-central AZ.


- Near to slightly above normal temperatures today and Saturday
  will cool to below normal by Sunday. Expect highs across the
  lower deserts to lower into the 80s by Sunday and persist
  through all of next week.

&&

.SHORT TERM /TODAY THROUGH SUNDAY/... After the first day of this
multi-day rainfall event, upwards of 0.5- 1.5" of rain has
already fallen across parts of south-central AZ, including Phoenix
and the foothills just to the north, while southwest AZ was
mostly missed and southeast CA had a few hundredths. Highest 24-hr
rainfall totals, through this morning, were northwest of Payson
with upwards of 2.0-2.5". Rain continues to fall across the
northern AZ high terrain and some light to moderate rain bands are
seen moving into parts of southwest AZ and southeast CA.
Satellite analysis shows a large cloud shield extending from TC
Priscilla, near the middle of Baja California, all the way through
the Colorado Rockies; being pulled between the subtropical high
over west TX and a deep Pacific low near OR. This record-level
tropical moisture - for this time of year - will continue to
stream up through the Desert Southwest through Saturday. Models
continue to show the remnant vorticity and forcing with Priscilla
moving through the region this evening and through Saturday
morning, from Yuma up through the central portions of AZ.

Scattered showers and isolated thunderstorms are expected to
continue through this afternoon across south-central AZ out through
the Lower Colorado River. Latest HREF, has a low probability of
rainfall reaching 1.00" through this afternoon across the lower
deserts. While chances for flash flooding this afternoon are low out
in southeast CA and southwest AZ, the Flood Watch has been allowed
to continue and will expire at midnight tonight. Heading into this
evening and through Saturday morning, when the remnants of Priscilla
finally move through, a more expansive area of moderate to heavy
rain, with embedded thunder, is expected to move through the central
portions of AZ. Model soundings are showing potential for a deep
warm cloud layer (up to 10K ft) and efficient warm rain processes,
capable of producing widespread high rainfall totals. Highest
rainfall totals this evening through Saturday morning will likely
still favor the upslope foothill areas north and east of Phoenix,
including some of the same areas that have already seen 1+ inches of
rain. HREF probabilities of >0.50" during this period are 50% or
higher to the north and east of Phoenix and closer to 20% in
Phoenix. Rain rates are not expected to be too high with this round
of rain, so slower prolonged runoff leading to rises in dry or
lightly running creeks, streams, and washes is favored more than the
more rapid flash flooding risk.

Models continue to show dry mid and upper level air quickly moving
in from the west through the day Saturday, following passage of
Priscilla`s remnants, while maintaining abundant low level
moisture, at least across most of southern AZ. Drier boundary
layer air is expected to push through southeast CA and into parts
of southwest AZ through Saturday. Models even show somewhat of a
dry line developing by the end of the day Saturday, situated just
east of the Colorado River. This change, with drier air aloft and
less widespread cloud cover, will actually end up leading to
higher instability heading into Saturday afternoon for parts of
AZ, with CAPE up to 1000 J/kg. This increased instability will
transition the environment more to a convective environment with
scattered thunderstorms capable of producing higher rainfall
rates. This is when the flash flood threat will likely become more
of a threat for south-central AZ. Shear magnitudes up around
30-40 kts for sfc-6km will also support some organized stronger
thunderstorms Saturday afternoon. A supercell or two cannot be
ruled out. So, there may also be some strong gusty winds and
small hail risk with storms Saturday.

Heading into Sunday, the environment will remain favorable for
showers and storms across south-central AZ, as the boundary layer
moisture remains elevated. In some ways the environment may
become even more favorable for strong thunderstorms capable of
producing very heavy rainfall, gusty winds, and small hail.
Heading into Sunday, southern AZ will be under the right entrance
region of a strengthening upper level jet, with the phasing of the
subtropical jet and jet with the Pacific low as it progresses
inland through the Great Basin and Intermountain West. This better
upper level support along with remnants of TC Raymond sliding up
through Sonora looks like it may lead to an area of mid-level
convergence somewhere in south-central AZ. Some of the hi-res
models and global models support this, with indications of
potentially a convergent line of showers and thunderstorms
developing as early as Sunday morning. With this in consideration,
the Flood Watch for south-central AZ has been extended through
Sunday.

Temperatures still managed to get into the low to mid 90s in
portions of south-central AZ this afternoon, while areas out west
have reached the mid to upper 80s. Despite all the rainfall tonight
into tomorrow, high temperatures are again forecast to be slightly
above normal for this time of year. The warm air advection from the
south is keeping thing a little warmer than one might expect. It is
not until Sunday that temperatures dip below normal, largely due to
passage of the trough to the north, in addition to the rainfall.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
Forecast uncertainty remains quite high starting heading into the
beginning of next week with any additional moisture and impacts
indirectly associated with TC Raymond now likely to mostly stay to
the south over far southeast Arizona into Mexico. However, we
will still see plenty of upper level forcing associated with a
deepening Pacific trough diving southward through California early
next week. We are still likely to see fairly good moisture
hanging out from around Phoenix through eastern Arizona during
this time with PWATs anywhere from 0.8-1.1". Plenty of low and
mid-level moisture will be in place for additional shower and
thunderstorm chances through at least Monday, but the chances for
heavy rainfall will be more localized and likely reliant on any
potential thunderstorms. WPC has highlighted a Slight Risk on
their Day 4 and Marginal Risk Day 5 EROs east and southeast of
Phoenix. NBM PoPs are mostly between 20-40% for Monday across the
south- central Arizona lower deserts to 40-60% across the higher
terrain of eastern Arizona.

Further decreasing of moisture is likely to begin by Tuesday with
rain chances mostly lingering across the eastern Arizona higher
terrain. Drier air is likely to continue to move into the region
from the southwest as the main Pacific low slowly moves southward
along the California coast. The eventual progression of this
Pacific low is still fairly uncertain with guidance suggesting it
may gradually move over at least northwest portions of our region
during the middle of next week with additional slight chances for
rain focused over eastern Arizona. This low may hang out close
enough for additional slight chances for rain even into late next
week, but it should also be in a weakening phase.

Temperatures will definitely be influenced by the Pacific low next
week with highs likely dropping from just shy of normal through
the weekend to around 5-8 degrees below normal for much of next
week. The latest NBM forecast highs show readings dipping into
the low to mid 80s across the lower deserts for much of next week.

&&

.AVIATION...Updated at 0610Z.

South Central Arizona including KPHX,KIWA,KSDL, and KDVT:
The primary aviation weather concern through the TAF period will
be rain with isolated thunderstorms tonight with additional
activity expected by tomorrow evening. Continued shower activity
is expected to overspread the metro area through the overnight
hours tonight with embedded thunderstorms possible. This activity
may lead to gusty, erratic wind directions along with brief MVFR
visibilities with any heavy shower/thunderstorms. We should see a
lull in activity by mid to late morning Saturday before activity
increases again late afternoon into the evening. By tomorrow
evening, hi-res guidance show an extended period of showers and
thunderstorms developing across the Valley and persisting into
Saturday night. SCT-BKN cloud decks will mostly remain aoa 7-10
kft with briefly lowered decks with shower/thunderstorm activity.
Winds are expected to favor the W-NW into the overnight hours
before switching around to the E-NE overnight tonight.

Southeast California/Southwest Arizona including KIPL and KBLH:
Shower activity continues to spread to the east of the Colorado
River Valley with lingering light VCSH tonight. This activity will
continue to diminish over the next hour or so. Winds at KIPL will
generally favor an E-SE component throughout much of the period
with periods of variability. At KBLH, winds will initially favor
the N-NE, with periods of variability overnight, before southerly
winds prevail by late Saturday morning. SCT-BKN clouds will mostly
remain aoa 8 kft through tonight with a clearing trend Saturday
morning.

&&

.FIRE WEATHER...
Wetting rainfall will continue today over much of the area with
more of a focus across southern and central Arizona. Rain may be
moderate to heavy at times leading to localized flooding,
especially over higher terrain areas. Elevated moisture levels
will keep MinRHs above of 30-40% through Saturday with drier air
eventually working into the western districts by Sunday. East
northeasterly winds will persist across the eastern districts with
northerly winds over the western districts today before shifting
to the southwest on Saturday. Occasional wind gusts between 20-30
mph will be possible during the period. Additional chances for
showers and thunderstorms will be possible Sunday through Tuesday
across the eastern districts.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flood Watch until midnight MST tonight for AZZ530>533-535-536.

     Flood Watch through Sunday evening for AZZ534-537>563.

CA...Flood Watch until midnight PDT tonight for CAZ560>570.

&&

$$

SHORT TERM...Benedict
LONG TERM...Kuhlman/Benedict
AVIATION...Smith
FIRE WEATHER...Kuhlman