650
FXUS65 KPSR 201824
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1124 AM MST Thu Nov 20 2025

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- Periodic rain showers with a few isolated thunderstorms continue
  early this morning across central and eastern portions of Arizona,
  and will slowly come to an end through the late morning and
  afternoon hours.

- The Flood Watch for northeastern Maricopa County remains in
  effect through 6am MST.

- Another weather system will then bring very good chances for moderate
  rainfall Thursday night and Friday across southeast California
  and southwest Arizona with light rain chances extending through
  the rest of southern Arizona on Saturday.

- Temperatures through the end of the workweek will be around 10 degrees
  below normal and steadily rise to near normal by early next
  week.

&&

.SHORT TERM /TODAY THROUGH FRIDAY/...
Early this morning, upper level water vapor satellite imagery and
objective analysis show a clearly defined upper level closed low
pressure system, currently centered over Southwestern AZ.
Additionally, there is a deep trough off the coast of the Pacific
NW that will dive southward into our area later today and into
Friday. The low pressure system in southwestern AZ is causing the
light shower activity across central and eastern portions of AZ.
Water vapor satellite imagery continues to show moisture streaming
into central and eastern AZ, that is supporting the ongoing
shower activity, along with drier air starting to push into
western and southern portions of AZ, where activity has ended or
is coming to an end. Current PWAT values are around 0.6-0.8",
which is around 180- 200% of normal for this time of year, across
central and eastern portions of the state. MUCAPE vales remain
limited, only around 100- 250 J/kg, however, this has been enough
to support some isolated thunderstorm activity. So, while most of
this activity will be showers, some isolated thunderstorms remain
possible. Additional rainfall totals for this activity are
0.00-0.25" across central AZ (including the Phoenix Metro), and
0.20-0.50" isolated 0.75-1.00" across the higher terrain in
eastern AZ. These rainfall totals could flooding concerns.
Therefore, the Flood Watch for northeastern Maricopa County
remains in effect through 6am MST.

This initial low pressure system will progress eastward across AZ
through the morning and into the afternoon, becoming an open wave by
the late morning/early afternoon hours. Additionally, the
aforementioned deep trough off the coast of the Pacific NW will
quickly dive southward along the Pacific coast throughout the day
today, becoming a closed low in the process. Part of the energy
associated with the low causing the ongoing shower activity across
AZ will get wrapped up into the low diving southward along the
Pacific coast. The rest of the energy will quickly advect into the
Plains as a shortwave trough tonight into Friday.

The second low pressure system that will be diving southward along
the Pacific coast today will bring additional rain chances to the
region late tonight-Sunday. The low will continue to push southward
tomorrow eventually settling just off the northern coast of the Baja
by late Friday night. This low will merge with an Atmospheric River
in southern CA late tonight/early Friday and will push PWATS to a
0.70-1.00" (180-230% of normal) range across SE CA and SW AZ. These
high PWAT vales in conjunction with the low pressure system and it`s
associated vorticity will lead to really good rainfall chances (60-
80%) across SE CA and SW AZ. Models show MUCAPE values of 100 J/kg
or less, so most, if not all, of the activity will remain as showers
with little to no thunderstorms expected (only a 10-20% chance of a
few isolated thunderstorms). Rainfall totals of 0.50-1.00" are
currently forecasted across SE CA and SW AZ from late tonight
through Friday. Some higher rainfall totals, of over an inch, are
expected, especially over higher elevation areas of southeast
California and where any banding of heavier showers occurs. It seems
fairly likely this will cause some flooding issues on Friday for the
typical flood prone areas and a Flood Watch may end up being needed.

Some of the shower activity will try to push into portions of
central AZ by Friday afternoon and evening. However with PWAT values
around 0.5-0.7", minimal rain is expected to reach the ground and
most activity may just be virga showers. Little to no
accumulations is expected across central AZ on Friday. The low
will eventually start to move onshore and then eastward into AZ by
Saturday afternoon and into Sunday (this and associated rain
chances are discussed in the long term discussion, see below).

These low pressure systems along with the clouds and associated
rainfall chances will help to keep temperatures well below normal
through at least the end of the workweek. Temperatures will be 7-15
degrees below normal today and tomorrow. Across SE CA and SW AZ,
afternoon high temperatures are forecasted to be in the mid to upper
60s to near 70 degrees today and in the upper 50s to low 60s
tomorrow. Across the south-central AZ lower deserts, afternoon highs
will be in the low to mid 60s today and in the mid 60s tomorrow.
Across the higher terrain, afternoon high temperatures will be in
the 50s today and tomorrow. Low temperatures both morning will range
from the mid 40s to low 50s across the lower deserts, the warmer
temperatures are expected in the more urban areas. The higher
terrain areas will see morning lows ranging from the mid 30s to the
mid 40s. With the highest elevations seeing temperatures near
freezing.

&&

.LONG TERM /SATURDAY THROUGH THURSDAY/...
As mentioned above, the second closed low, bringing shower
chances to SE CA and SW AZ late Thursday into Friday, will finally
start to move onshore by Saturday afternoon. The center of the
low will move into SW AZ by early Sunday morning and move
northeastward through the day. Activity will linger through
Saturday morning across SE CA and into Saturday afternoon across
SW AZ before ending as the low pressure system moves east of these
locations. Additional rainfall totals of 0.00-0.25" are expected
on Saturday.

As for central and eastern portions of AZ, PWAT values will remain
in the 0.5-0.7" range through Saturday morning, keeping rain chances
less than 30%. Minimal accumulations are also expected as most
activity may just be virga showers through Saturday morning. By
Saturday afternoon, when the center of the low pressure system moves
into central AZ, PWATs will raise to 0.7-0.9" range (180-210% of
normal). PWATs will be around 0.6-0.8" across the higher terrain in
eastern AZ. This is when the best chance for showers will be across
central (40-50%) and eastern AZ (60-70%). Models show no instability
with this round of activity, so it should remain as just showers and
no thunderstorms across central and eastern portions of the state.
The low will be east of AZ Sunday night and quickly advect into the
Plains on Monday. PWAT values will fall back below 0.7", and with
the low and its associated forcing east of us rain chances across
our region will be back to zero by Sunday night. For Saturday-
Sunday, rainfall totals of 0.00-0.30" are currently forecasted for
south-central AZ and 0.20-0.50" across the higher terrain of
eastern AZ.

With the low pressure system still in our area, temperatures will
remain below normal through the weekend. Lower desert locations will
see afternoon high temperatures in the mid 60s on Saturday and in
the low to mid 60s (south-central AZ) and upper 60s to around 70
degrees (SE CA and SW AZ) on Sunday. Higher terrain areas will see
afternoon highs in the upper 50s to low 60s on Saturday and in the
50s on Sunday. Morning lows, both days, will range from the upper
40s to mid 50s across the lower deserts and in the 40s across the
higher terrain areas.

With the low pressure system well to our east on Monday heights
aloft will rise leading to a gradual warming trend. Ensemble models
are in good agreement that no additional weather systems are
expected across our region through at least the middle of next
week, which means dry conditions are expected across the region
next week. Additionally models are in good agreement that heights
aloft will continue to rise next week leading to a gradual warming
trend, with temperatures returning to near normal by early next
week. This will result in afternoon highs in the low 70s across
the lower deserts and in the mid to upper 60s across the higher
terrain. Additionally morning lows will be in the 40s to low 50s
across the area next week.

&&

.AVIATION...Updated at 1822Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Shower activity has mostly pushed east of the terminals this
morning, however, low CIGs will continue to linger into the
afternoon. MVFR CIGs down to 2-3 kft are expected to persist
through midday before climbing to around 5-6 kft for this
afternoon. Clouds are expected to mostly scatter out by this
evening with FEW decks aoa 6 kft. Winds through this afternoon
will favor a westerly component before switching around to the
east by around 00Z-01Z. Another weather system will begin pushing
into the region for Friday, bringing increasing cloud cover along
with a few light showers/virga toward the end of the TAF period.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns are anticipated through this
afternoon under mostly clear skies. Winds will favor the W at KIPL
through this evening and S-SW at KBLH. A weather system will bring
increasing cloud cover and rain chances to southeast California
starting tonight with the best chances occurring Friday. Chances
for MVFR CIGs will climb upwards of 30-50% by the end of the TAF
period with a 20% chance of IFR CIGs.

&&

.FIRE WEATHER...
Periodic showers along with a few isolated thunderstorms will
continue across central and eastern AZ this morning and
afternoon, providing very good chances for wetting rains. Below
normal temperatures and elevated moisture will remain in place
keeping MinRHs in a 40-70% range following excellent overnight
recovery greater than 80%. Locally gusty winds upwards of 20 mph
will be possible at times, though weaker wind speeds will be more
common through the period. Another weather system is expected to
move mainly across the western districts late tonight and
continuing through Friday leading to very good chances for
wetting rains with more scattered shower activity across the
eastern districts Saturday through Sunday. Temperatures will
mostly remain below normal through the weekend with humidities
staying elevated.

&&

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

$$

SHORT TERM...Berislavich
LONG TERM...Berislavich
AVIATION...Smith
FIRE WEATHER...Berislavich