613
FXUS65 KPSR 012141
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
241 PM MST Tue Jul 1 2025

.KEY MESSAGES...

- Extreme heat conditions will continue today across the lower
  deserts as high temperatures top out between 110-115 degrees.

- Isolated to scattered thunderstorms, with strong gusty winds and
  blowing dust being the main threats, will impact much of south-
  central and eastern Arizona this afternoon and evening and
  again on Wednesday.

- Drier conditions will end any rain chances starting Thursday
  night with near normal temperatures lasting into Saturday,
  before heating back up Sunday into Monday.

&&

.NEAR TERM /THROUGH THIS EVENING/...
Early afternoon convection has begun along the Mogollon Rim and
White Mountains, with a slow progression to the south and west.
Some lingering light showers/virga continues in a north- south
orientation along or west of the Lower Colorado River Valley where
the nose of the higher moisture levels are meeting some broad
scale ascent with the troughing feature centered along the West
Coast. Showers/storms will continue to progress in a southwesterly
progression this afternoon and evening along the higher terrain
of eastern Arizona, with enhanced outflows reaching the lower
deserts this evening which is likely (50-70%) to result in winds
gusting 40+ mph as inverted-V sounding profiles will support
strong downburst winds. Hi-res models are more excited about
convection developing over the the valley floors later this
evening than previous runs, but due to the very dry antecedent
conditions, still leaving relatively low (10-20%) chances for this
evening and into the overnight period across the south-central
Arizona lower deserts.

.SHORT TERM /TONIGHT THROUGH WEDNESDAY NIGHT/...
For tonight into Wednesday morning, the modest monsoon moisture
is likely to have pushed as far west as western Maricopa Co. with
drier air still getting pulled northeastward into southeast
California as the Pacific low moves onshore across central
California. By Wednesday afternoon, we should see better upper
level forcing over our area from the incoming Pacific low and this
should combine with the modest monsoon moisture over south-
central and eastern Arizona. Despite PWATs only being around 1.3"
Wednesday afternoon, the colder air aloft and the forcing from the
incoming Pacific low are likely to help overcome the limited
moisture. The colder air aloft and steeper lapse rates will help
to build 500-1000 J/kg of MUCAPE for Wednesday afternoon. The 06Z
HRRR shows a scenario where convection not only develops over the
higher terrain Wednesday afternoon, but also over Pima and
southern Maricopa/western Pinal Counties with the help of the
trough. The higher storm areal coverage is likely to produce
several storm outflows and likely additional development along
outflow collisions, likely affecting portions of the Phoenix
metro. Just like today, a dry sub-cloud layer should promote a
strong gusty wind and blowing dust threat. One negative we see for
storm organization and duration is the fairly weak winds aloft
and overall low shear. Potential rainfall amounts for Wednesday
afternoon and evening will be better than today with the best
cells potentially dropping localized amounts of up to an inch, but
most areas are not likely to see more than 0.25". NBM PoPs of
15-20% over the south-central Arizona lower deserts seemed too low
and have been adjusted upward to closer to 25-30%. These higher
PoPs may still may underdone.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Starting Thursday, guidance shows the weakening Pacific low moving
eastward into western portions of the Desert Southwest. This will
push west southwesterly dry flow over our area throughout the day
Thursday. The timing of this drying is still a bit uncertain, but
it likely won`t be fast enough to stop some isolated to scattered
showers and thunderstorms from forming Thursday morning and
afternoon. PoPs Thursday are actually the highest over the
Phoenix area in the morning at 20% with the drier air likely
ending chances in the afternoon for the lower deserts. Higher
terrain areas east of Phoenix should keep rain chances through the
afternoon hours before ending in the evening as the remnants of
the low shifts into northeast Arizona. The passage of the low on
Thursday will also keep temperatures from reaching the normal for
the date with highs mostly between 100-105 degrees.

For the 4th of July, dry westerly flow will end any rain chances
and temperatures will maybe gain a degree over Thursday`s highs.
Overnight temperatures will also noticeably improve by Friday
with lows mostly in the 70s for the lower deserts to the lower 80s
within the urban core of Phoenix. The weather pattern for the
coming weekend will initially keep the broad cyclonic flow in
place, but we are likely to see the sub-tropical ridge to
gradually build back in from the east with a high center forming
somewhere over New Mexico. This should keep a dry westerly flow in
place through the weekend with no realistic rain chances. As the
ridge gradually takes over again across our region, temperatures
are expected to gradually heat up with highs nearing the 110
degree mark again as early as Sunday. There is still some model
uncertainty for the first half of next week, but trends are
showing the ridge shifting more toward the Four Corners area by
next Tuesday or Wednesday allowing moisture and rain chances to
again return to portions of the area.

&&

.AVIATION...Updated at 1730Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
The early morning visibility restrictions have slowly improved to
P6SM however there will continue to be hazy conditions this
afternoon with some lowered slantwise visibilities. Very high
confidence remains regarding an outflow boundary moving through
the valley TAFs this evening out of the E/NE thanks to high
terrain convection this afternoon. Best timing for the arrival of
this boundary looks to be between 01-02Z, bringing gusts in excess
of 30 kts and areas of blowing dust. A lot of uncertainly on how
low visibilities will get in dust, but not expecting a significant
reduction at this time. Chances for precipitation in the valley
still looks very low (10-20%) tonight, so no mention of SH/TS in
the TAFs at this time.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns are expected during the next 24 hours.
Early afternoon variability will be common before winds resume
their diurnal trends (W at KIPL, S`rly at BLH) later this
afternoon and evening. Many just some few/sct mid and high level
clouds.

&&

.FIRE WEATHER...
Today will again be very hot, but with a slight uptick in moisture
levels pushing MinRHs this afternoon into the teens to up to 20%
for much of the eastern districts. Thunderstorm activity will
also increase today over eastern Arizona higher terrain with
chances upwards of 40%. Gusty erratic winds are likely to occur
with the thunderstorm activity, with outflow winds expected to
move into the south-central Arizona lower deserts by early
evening. Wednesday should bring another active weather day across
the eastern districts with shower and thunderstorm chances at
around 50% over the higher terrain to around 30% into the lower
deserts. Humidities will continue to improve on Wednesday with
MinRHs around 20% for the lower deserts to 30-35% in Gila Co.
Storm chances diminish starting Thursday and end completely by
Friday. Drier air will filter into the region by the weekend with
MinRHs falling to 10-15% by Sunday. Temperatures will run near
normal from Thursday through the weekend.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST this evening for AZZ530>540-
     542>544-546-548-550-551-553-554-559.

     Blowing Dust Advisory until 8 PM MST this evening for AZZ553-554.

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

&&

$$

NEAR TERM...Young
SHORT TERM/LONG TERM...Kuhlman
AVIATION...Frieders
FIRE WEATHER...Kuhlman