110
FXUS65 KPSR 091740
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1040 AM MST Wed Jul 9 2025

.UPDATE...Updated 18z Aviation Discussion.

&&

.KEY MESSAGES...

-Strong high pressure over the region will result in well above normal
 temperatures through Thursday with temperatures peaking today as
 afternoon highs reach and exceed 115 degrees across the lower
 desert communities.

-The heat will result in widespread Major HeatRisk with Extreme
 Warnings in effect for much of the region through Thursday.

-Slightly cooler temperatures are expected by Friday through this
 weekend, but will remain above normal

-Thunderstorm activity will continue to be limited to the Arizona
 high terrain and southeast Arizona during the next several days.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
The latest objective analysis shows an expansive subtropical high
across the Desert Southwest, with 500 mb heights of 597-598dm, which
is near record heights for this time of the year. This will
translate to afternoon highs today across most of the lower deserts
communities of 114-118F, resulting in widespread Major HeatRisk
with Extreme Heat Warnings in effect across virtually the entire
region, including the higher terrain zones below 4000 feet east of
Phoenix. Therefore, it is very essential given this dangerous
heat episode to take all the necessary heat precautions to prevent
any heat-related illnesses. Daily record highs are likely to be
in jeopardy, especially in both Phoenix and El Centro where the
forecast highs for today at both sites are 118F (Previous record
in Phoenix was 116F set back in 2024 and 1958 and in El Centro was
117F set back in 1958).

Heading into Thursday, a weakening area of low pressure currently
sitting off the northern CA coastline will migrate eastward towards
Intermountain West Region causing the high to flatten out a bit
with 500 mb height fields decreasing slightly to 594-597dm. As a
result, afternoon highs will be slightly cooler ranging between
110-116F across the lower deserts, but still hot enough to result
in areas of Major HeatRisk, especially with early morning lows
expected to be in the upper 80s to low 90s. Therefore, the Extreme
Heat Warnings continue in effect across the lower deserts. The
Extreme Heat Warning across the higher terrain areas below 4000
feet east of Phoenix was also extended through Thursday evening as
the latest NBM came in a couple of degrees warmer, boosting the
HeatRisk to the major category across these zones. The weakening
low migrating eastward across the Intermountain West Region will
also generate enough of a pressure gradient to result in some
gusty winds upwards of 25-35 mph across much of south-central AZ
during the afternoon and early evening hours, resulting an
elevated fire danger risk.

In terms of the convective side of things, very strong subsidence
will continue to hinder any potential for thunderstorm activity
across the lower deserts with any afternoon activity expected across
the higher terrain areas, mostly near the vicinity of the White
Mountains towards southeast AZ. A few showers and isolated
thunderstorm cannot be ruled out across far eastern Gila County.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
The subtropical high is expected to continue to slowly migrate
westward towards the southern CA coastline heading towards the end
of the week through the upcoming weekend. This will result in 500 mb
height fields to decrease slightly closer to 591-594dm. This will
translate to slightly cooler temperatures, but still remain a few
degrees above normal as afternoon highs will average around 110
degrees across the lower deserts with widespread Moderate
HeatRisk.

The convective potential through the weekend will continue to be
very limited as the upper-level flow pattern will remain unfavorable
for any deep moisture influx. In fact, as the high settles over
the southern CA coastline, the flow will turn out of the north,
bringing drier air with PWATs dropping below one inch during the
weekend. However, enough low-level moisture may still be present
for some afternoon convection to materialize, mainly across the
vicinity of the White Mountains and the southeastern third of AZ.
Heading into next week, model guidance continues to show the high
repositioning towards the Four Corners Region, especially by the
middle of the week. This would result in a more favorable flow
pattern for deeper moisture advection, with convective coverage on
the increase across the higher terrain areas initially before
chances increase across the lower deserts, more likely by the
latter half of the week.

&&

.AVIATION...Updated at 1740Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major aviation weather concerns will exist through Thursday
morning under FEW mid/high clouds. Winds will follow similar
trends to that of the last 24 hours. Directions have shifted out
of the west and will be followed by a period with W/NW gusts to
around 20 kts late this afternoon. Thursday morning, confidence is
lower than usual on exact wind directions at KPHX, though they
will likely remain AOB 5 kts.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns are expected through the next
24 hours under occasional scattered mid/high cloud decks. A
westerly wind component will be favored at KIPL, with a period of
variability anticipated this afternoon. At KBLH, expect an
extended period of variability before SW winds establish, with
sustained speeds around 10-15 kts and occasional higher gusts this
afternoon into the evening. Southerly winds are forecast at both
sites around the 14-15Z timeframe tomorrow morning.

&&

.FIRE WEATHER...
Regionally dry conditions and above normal temperatures will
persist through the next week as lower deserts highs reach and
exceed 110 degrees nearly every day, with temperatures peaking
today as most lower desert locations reach and exceed 115 degrees.
MinRH values will range from 10-20% each day, while MaxRH values
will be the lowest through tonight at 20-40% before increasing up
to 30-50% the rest of the week for most of the area. One exception
will be across Imperial and southern Yuma Counties where periodic
gulf surges will result in MaxRH values in excess of 50-60%. The
overall wind pattern will follow the familiar diurnal trends, with
some afternoon/early evening breeziness with 15-25 mph peak
gusts. An uptick in the winds is expected Thursday and Friday
afternoons with 25-35 mph peak gusts. This may lead to locally
elevated fire weather conditions, primarily on Thursday due to
drier conditions. Very minimal rain chances will exist during the
next several days, focused mainly across the eastern and
southeastern third of AZ, with CWR <10% through at least the
upcoming weekend.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Thursday for AZZ530>556-
     559>562.

     Heat Advisory until 8 PM MST this evening for AZZ557-558-563.

CA...Extreme Heat Warning until 8 PM PDT Thursday for CAZ560>570.

&&

$$

SHORT TERM...Lojero
LONG TERM...Lojero
AVIATION...Whittock/95
FIRE WEATHER...Lojero/Benedict