489
FXUS65 KPSR 011206
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
506 AM MST Tue Jul 1 2025

.Update...Updated Aviation Discussion

&&

.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.

&&

.SHORT TERM /TODAY THROUGH WEDNESDAY NIGHT/...
The first taste of the monsoon has arrived with the ridge center
positioned near the Four Corners area since Sunday night. This has
allowed for easterly flow into eastern Arizona and a gradual
increase in low and mid level moisture. Marginal moisture will
continue to advect into eastern and central Arizona over the next
24-36 hours pushing PWATs up to 1.2-1.3" over south-central
Arizona. However, the moisture today is expected to be limited
enough to mostly favor higher terrain areas. The latest hi-res
CAMs show convection firing this afternoon along the Mogollon Rim
into the White Mtns as well as over southeast Arizona.

This activity should produce at least one organized easterly
progressing outflow reaching Pinal and eastern Maricopa County
sometime between 4-7 pm. This expected outflow has a high (~70%)
probability of producing 35+ mph winds over the aforementioned
areas and a 30-50% probability through the rest of the Phoenix
metro. The outflow winds are likely to produce areas of blowing
dust across Pinal Co., where patchy dense dust will be possible,
with more limited blowing dust potentially affecting portions of
the Phoenix area. Hi-res guidance also shows some isolated
convection developing along the advancing outflow, but fairly
limited moisture into the lower deserts should keep the shower
and/or thunderstorm activity fairly sparse. We are currently
carrying PoPs of around 30% across the higher terrain and into
central Pinal Co. to 15-20% within the Phoenix metro. The limited
moisture today will keep rainfall amounts fairly light with only
very localized amounts up to 0.5-0.75" possible.

Temperatures today are forecast to be a couple degrees lower than
Monday with readings between 110-115 degrees, but a slight
increase in surface dew points will make it feel just as hot
across the lower deserts. The Extreme Heat Warnings are still in
effect through 8 pm today for all of the lower deserts across
south-central and southwest Arizona and southeast California.

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 0536Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
Most of the TAF sites early this morning have seen VIS down to 3-5
miles thanks to lingering lofted dust from overnight elevated
winds. These VIS reductions may stick around for the next several
hours as there is no efficient way at this time of day to clear
the dust out. It is possible, if not likely, that current TEMPO
groups are extended due to the low confidence surrounding this
near-term impact. Winds during this timeframe will be generally
out of the E-SE, slowly veering more to the S by this afternoon.
However, winds during the early afternoon window may see frequent
150v220 variability.

Very high confidence remains regarding an outflow boundary moving
through the metro this evening out of the E/NE thanks to high
terrain convection this afternoon. Best timing for this boundary
still looks to be between 01-02Z, bringing gusts in excess of 30
kts and areas of blowing dust. As of now, the only VIS reductions
included in the TAFs are for KPHX and KIWA, but slantwise VIS
reductions cannot be ruled out for the other terminals. Chances
of precipitation have increased slightly overnight (10-20%), but
still remain too low to warrant inclusion any mention of SH/TS in
the TAFs at this time, but isolated convection may develop over
terrain features within 40 miles of KPHX, like over the
Superstitions and the Estrellas. Cloud bases should remain above
12k ft.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns are expected during the next 24 hours.
Morning variability will be common before winds resume their
diurnal trends (W at KIPL, S`rly at BLH) later this afternoon and
evening. Clear skies will be present through the majority of the
period, but windows of FEW-SCT bases around 15k ft will be
observed this morning and perhaps again this evening/tonight.

&&

.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 from 4 PM this afternoon to 8 PM MST this
     evening for AZZ553-554.

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

&&

$$

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