623
FXUS65 KPSR 141700
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1000 AM MST Tue Jul 14 2026

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- Hot and muggy conditions will continue through mid week,
particularly across southeast California and southwest Arizona where
Extreme Heat Warnings have been issued through Thursday.

- A weather disturbance will bring widespread shower and
thunderstorm activity on Thursday and Friday with the potential for
heavy rainfall and localized flooding over eastern and central
Arizona.

- Temperatures will cool later this week with below normal
temperatures across much of Arizona to near normal for southeast
California by Friday.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY/...
The Desert Southwest monsoon is well underway and looks to remain
active at least for the next couple of weeks. The subtropical ridge
has moved far enough to the north to allow for very good moisture
transport into the region over the past few days. Deep moisture and
conditions conducive for monsoon storms are likely to be present for
most days through the weekend and probably longer. There are two
main forecast concerns over the next several days: First is the
Extreme Heat impacting portions of the western deserts today through
Thursday, and then the heavy rain potential for the eastern 2/3rds
of Arizona starting Thursday.

Currently, a near record strength upper level ridge remains centered
over the North-central U.S., extending through the entire central
U.S. and much of the Rockies. Moist southeasterly flow continues
across Arizona and even extending as far north as Montana. This
fetch of moisture is likely to remain in place for a good amount of
time with an active eastern Pacific tropical scene also helping to
direct moisture northward through Mexico.

The convective activity on Monday was expansive enough to overturn
the atmosphere throughout much of southern and central Arizona, so
today`s convective potential will be much more limited. Forecast
temperatures today across south-central Arizona have been lowered
slightly due yesterday`s rainfall activity with some lower desert
areas not even reaching normal readings. However, the western
deserts will heat up even further today under mostly sunny skies as
highs likely reach 110 degrees. Boundary layer moisture has also
increased enough to push surface dew points into the mid 60s to the
lower 70s. This amount of moisture will somewhat curtail
temperatures, but it will make it feel much more uncomfortable as
heat indices top 110 degrees across the western lower deserts to as
high as 115 degrees in the El Centro area. Guidance indicates a
worsening of the heat across the western deserts Wednesday into
Thursday with highs peaking at 110-113 degrees, but with heat
indices as high as 113-119 degrees. An Extreme Heat Warning has been
issued for the lower deserts of southeast California and throughout
the Lower CO River Valley starting late this morning through
Thursday evening. Overnight forecast lows right around record high
minimums were also a factor in the Extreme Heat Warning issuance.

Atmospheric instability is expected to recover starting Wednesday
with hi-res CAMs showing good coverage of afternoon convection
forming over higher terrain areas with a decent likelihood of it
moving into the lower deserts during the evening hours. As of now,
the coverage may end up being on par or even slightly better than
what occurred last evening. The upper level flow pattern later on
Wednesday should begin to become more favorable for storm
development over eastern Arizona as a large upper level low moves
eastward into Texas. The threat for any strong to severe storms on
Wednesday looks to be very marginal as forecast instability is only
around 500-750 J/kg and the winds aloft are overall weak. However,
we are more likely to see at least a minor threat of heavy rainfall
and localized flooding starting Wednesday as low level mixing ratios
remain around 11-12 g/kg and the steering flow weakens.

&&

.LONG TERM /THURSDAY THROUGH MONDAY/...
Active monsoon weather is expected to continue through the period
with Thursday and Friday showing the highest potential for impactful
weather. An important ingredient for more organized showers and
thunderstorms is expected to be introduced by Thursday. A large
easterly disturbance will continue to track across Texas into New
Mexico Wednesday into Thursday before stalling out over New Mexico
on Friday. This is expected to place at least the eastern half of
Arizona in a favorable ascent region for Thursday and Friday, and
potentially into Saturday.

Thursday has the better odds of being the best convective day as we
are anticipating the highest instability to go along with the upper
level support. The amount of cloud cover on Thursday is still a
question and it very well may influence the amount of potential
instability, but forecast soundings still show upwards of 1000 J/kg
of CAPE for Phoenix. Additional moisture transport into the region
should also push PWATs to between 1.8-2.1", suggesting heavy
rainfall will an increasing threat. NBM PoPs increase to 70-80% for
eastern and south-central Arizona Thursday, while WPC has introduced
a large Slight Risk for excessive rainfall. We will continue to
monitor the latest guidance as Flood Watches are likely to be needed
for some areas later this week. Shower and thunderstorm chances
should also expand westward toward the Lower CO River Valley
Thursday night with chances continuing areawide through at least
Friday. As of now, a Slight Risk for excessive rainfall is also
present for Friday, but the uncertainty is higher as instability is
likely to be lower and the easterly wave should begin weakening on
Friday.

Abundant monsoon moisture will persist over the weekend into early
next week with day-to-day storm chances continuing, but forecast
uncertainty is quite high. Another easterly wave looks to be
possible at some point during the first half of next week which may
bring another round of higher storm/rainfall coverage.

Forecast temperatures for later this week into next week are also of
low confidence due to the expected convective potential over much of
the area. The latest NBM forecast highs show readings dipping below
normal over the south-central Arizona lower deserts as early as
Thursday, but remaining right around normal for the western deserts.
Although model forecast spread for temperatures is quite high
beginning Thursday, it seems likely the Phoenix area will see at
least a day or two in the 90s on Friday and/or Saturday. Depending
on the amount of cloud coverage and even morning/afternoon rainfall
on Friday, highs may struggle to reach the low to mid 90s.

&&

.AVIATION...Updated at 1700Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Winds will be the main weather issue through Wednesday afternoon
under periods of mid/high cloud decks. Directions may remain
variable into early this afternoon before settling on a W/SW
direction. Mountain thunderstorms should be less pronounced today,
and likely not descending into the terminal footprint. Even outflow
winds may not impact all terminal locations, and there is large
uncertainty regarding the timing of an easterly wind shift
overnight. Have pushed back timing of an easterly shift, and it`s
not impossible that KPHX never truly turns east, and just becomes
variable for a few hours Wednesday morning.

Wednesday evening outlook: Chances for stronger, gusty easterly
outflow winds and direct TS impacts will increase substantially late
afternoon/early Wednesday evening. Brief periods of MVFR/IFR
visibility in TSRA are possible early/mid evening.


Southeast California/Southwest Arizona including KIPL and KBLH:
No major weather issues will exist through Wednesday afternoon under
periods of mid/high level cloud decks. Winds will generally vary
from a diurnal SE component to a nocturnal SW direction. Any gusts
will be limited and directions may become variable for a period
around sunrise.

&&

.FIRE WEATHER...
Elevated moisture levels will result in daily chances for showers
and thunderstorms over the eastern districts through Wednesday
before increasing in coverage and spreading westward late week.
Humidities will continue to improve through the rest of the week,
while temperatures eventually cool to around or even below normal by
Thursday. MinRHs are expected to hover between 20-30% over the lower
deserts to 30-40% over the AZ high terrain through Wednesday before
improving further late week. Outside of potential thunderstorm
outflows, winds will tend to be light and somewhat favor diurnal
trends.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Thursday for AZZ530-532.

CA...Extreme Heat Warning until 8 PM PDT Thursday for CAZ562-563-
     565>567-569-570.

&&

$$

SHORT TERM...Kuhlman
LONG TERM...Kuhlman
AVIATION...18
FIRE WEATHER...Kuhlman

NWS PSR Office Area Forecast Discussion