935
FXUS65 KPSR 092123
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
223 PM MST Thu Oct 9 2025

.KEY MESSAGES...

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

- Active weather with multiple rounds of showers and embedded
  thunderstorms will begin today and persist through at least
  Saturday. Some locations could receive rainfall totals exceeding
  2.00" which will promote excessive runoff into area watersheds,
  leading to flooding of low lying areas.

- Near normal temperatures today and Friday will cool to below
  normal starting this weekend. Expect highs across the lower
  deserts to lower into the 80s by Sunday and persist through the
  majority of next week.

&&

.SHORT TERM /TODAY THROUGH SATURDAY/...
The threat for heavy rainfall and flooding will begin today and
increase through this weekend. This will be a long duration rainfall
event across the Desert Southwest which could potentially last
through early next week. Due to the tropical nature of the airmass
in place ahead of TC Priscilla, efficient rainfall processes will
lead to hydrological concerns as the event unfolds. The main
concerns will be excessive runoff leading to flooding of area
streams, creeks, and washes which will drain into low lying areas.
Everyone should exercise caution and heed any warnings that are
issued. Anyone traveling through the region should prepare for
delays and poor driving conditions. Always remember to turn around
don`t drown if encountering flooded roads.

Heading through the rest of this evening and tonight, we will
continue to see tropical moisture streaming up through interior MX
into AZ. Latest CAMs indicate the main focus for rainfall will
extend from SE CA through SW AZ and into N AZ overnight where lift
will be maximized ahead of a deepening upper-lvl trough over
NorCal. This initial rain band may be more broken and not as
consistent as previous model runs indicated, however there will
still be a risk for locally heavy rainfall across the western
deserts tonight. By early Friday morning, the remnants of TC
Priscilla will begin to be pulled nwd up the spine of the Baja
California and provide a focus for a band of heavier rainfall to
develop over SW AZ into N AZ. This will become the main band of
showers and storms that will slowly shift SE with time through
this weekend. Rain chances will continue to increase from W to E
throughout the day on Friday to upwards of 50- 60% across the
western half of the forecast area. Due to the abundant moisture
and cloud cover across the region on Friday, temperatures will
cool back down around normal and slightly below normal for
locations that do see rainfall.

The bulk of the rainfall is expected to occur from Friday evening
through Saturday morning as the mid-level remnants of TC Priscilla
are expected to progress through Arizona from southwest to northeast.
Enhanced forcing from the arrival of the mid-lvl trough with
strong mid-level jet 40-50 kts should provide for fairly steady
moderate to heavy rainfall focused across south-central Arizona
Friday night and Saturday morning. Due to the upslope component
of the mid-lvl flow, the foothills and higher terrain NE of
Phoenix will likely be the bullseye for highest rainfall totals.
Eventually this activity should gradually shift more over the
higher terrain of southcentral AZ by Saturday afternoon with
periods of showers likely lasting into the overnight hours
Saturday night. One important thing to note is if there is enough
clearing on Saturday afternoon, we could see steepening lapse
rates and increased instability across Maricopa County including
the Phoenix Metro which could result in isolated thunderstorms.
If this were to occur, a few storms could be strong and produce
small hail and gusty winds.

Forecast rainfall amounts have not changed much from previous
forecasts with amounts likely averaging 0.3-0.5" over southeast
California and 0.5-1.0" over southwest Arizona. Higher amounts are
expected over south-central and eastern Arizona where 1-1.5" is
likely across the lower deserts to 1.0-2.5" over higher terrain
areas. Localized higher amounts are expected to occur with a few
locations potentially pushing 2-3". These amounts may shift
slightly, but represent the most likely outcome based on the
current forecast.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
Considerable forecast uncertainty remains for Sunday through
Tuesday as a second tropical system may bring another period of
moderate to heavy rainfall to portions of Arizona. The best
potential is definitely expected to be over southeast Arizona, but
it very well could extend into our area. Guidance mostly agrees
the eventual remnants of this tropical system will traverse across
the Gulf of California on Sunday with another round of tropical
moisture shifting into at least southeast Arizona later Sunday
into Monday. The remnants of the TC are then likely to push
through Sonora Mexico providing ample forcing for rain across at
least southeast Arizona. The Pacific trough will also continue to
provide for good upper level support during this event as it is
likely one or more shortwaves will brush across northern portions
of the Desert Southwest.

Guidance shows moderate to heavy rainfall potential at least
extending into Gila County from as early as Sunday night through
as late as Tuesday afternoon with some members showing heavy
rainfall as far northwest as Phoenix. We will continue to monitor
for the potential for heavy rainfall through early next week and
can`t rule out the threat for some strong thunderstorms. The
tropical influence will likely push to the east of our region at
by later on Tuesday, but rain chances very well could persist
into Wednesday as models show a strong shortwave diving across at
least northern portions of our region later Tuesday into
Wednesday. However, by this point in time moisture availability
will be a concern as drier air is likely to be moving into the
region from the southwest.

Temperatures are forecast to drop going into the weekend with
readings eventually settling into the 80s for highs by Sunday. As
the Pacific trough begins to influence our region by early next
week, heights aloft will drop further and this will help to keep
temperatures below normal for several days. NBM forecast highs
show readings mostly in the low to mid 80s for the at least the
first half of next week and potentially even through all of next
week.

&&

.AVIATION...Updated at 0555Z.
South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
An initial band of light SHRA is moving across the Phoenix area
now. Additional spotty SHRA is seen behind the band to the south.
VCSH is in the TAFs through 20-21Z when there may be a break.
Additional, rounds of VCSH/-SHRA is expected during the TAF
period, mainly tonight and heading into tomorrow afternoon. SCT to
BKN clouds will prevail through the entire TAF period, with VFR
CIGs and lowest cloud bases around 8-10K ft AGL. An E`rly wind now
will turn more N`rly to NE`rly this afternoon. Some erratic wind
shifts are possible with any shower. Potentially to a brief S`rly.
Wind speeds will mostly be in the 5-12 kt range through the
period, with an occasional gust up to 15-20 kt. The potential for
TS this period is very low and then increases tomorrow afternoon
and evening.

Southeast California/Southwest Arizona including KIPL and KBLH:
Main aviation concern today is the potential for showers and
storms. Most of the activity through this afternoon looks to stay
outside of the vicinity of the terminals, with the highest
probability for convective activity being along the peninsular
mountains west of KIPL. VCSH mention in the TAF has been pushed
back to tonight. Multiple periods of showers are anticipated, with
another favored period beginning toward mid-morning tomorrow.
Winds a KIPL will shift to a W`rly to N`rly component this
afternoon, with extended periods of VRB, and KBLH will favor an
E`rly wind through this afternoon before shifting N`rly tonight.
FEW to BKN clouds decks, ~10kft, will persist.

&&

.FIRE WEATHER...
Tropical moisture will continue to progress through the region
today, allowing for increasing coverage of showers and isolated
thunderstorms. The main focus for wetting rainfall will be over
western half of the forecast area tonight before spreading into
southcentral Arizona Friday and Saturday. Moderate to heavy
rainfall will be likely at times. Easterly winds will persist
across the eastern districts through Friday with some gusts
upwards of 25-30mph, especially over the higher terrain. Winds
across the western districts should tend to favor the east today
and then out of the north northeast tonight into Friday. Due to
the increase in moisture and rain chances, temperatures will
gradually cool from near normal to below normal by this weekend.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Flood Watch through Friday evening for AZZ530>533-535-536.

     Flood Watch from Friday afternoon through Saturday evening for
     AZZ534-537>563.

CA...Flood Watch through Friday evening for CAZ560>570.

&&

$$

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