485
FXUS65 KPSR 072200
AFDPSR
Area Forecast Discussion
National Weather Service Phoenix AZ
300 PM MST Mon Jul 7 2025
.UPDATE...Updated Short Term Discussion.
&&
.KEY MESSAGES...
- Dry conditions and above normal temperatures are expected this
week with highs forecast to reach and exceed 115 degrees across
many of the lower desert communities Wednesday
- The heat will result in widespread Major Heat Risk with Extreme
Heat Warnings in effect for much of the region Tuesday through
Thursday
- Temperatures are forecast to lower a few degrees by the end of
the week through this weekend, but will remain above normal
- Thunderstorm activity will remain subdued due to strong high
pressure and lower moisture, and confined mostly to the Arizona
high terrain and Southeast Arizona
&&
.SHORT TERM /TODAY THROUGH TUESDAY/...
Strong high pressure remains centered near the AZ/NM border this
afternoon, with H5 heights around 594dam, and WV satellite shows
a cutoff low pressure circulation just off the CA coast. Aircraft
soundings out of Phoenix show minimal changes to the boundary
layer thermal profile over the last 24 hours. Thus, afternoon
temperatures today are expected to be similar to yesterday, with
lower desert highs forecast around 106-111 degrees. Through
Tuesday, modeling consistently shows the coastal low circulation
weakening while the high strengthens and shifts more into AZ. H5
heights are forecast to increase up to 597-598dam by the end of
the day Tuesday, which is right around record level for this time
of year. As a result, surface temperatures will further heat up.
Highs Tuesday are forecast to be 2-4 degrees warmer than today,
with lower desert highs more around 109-114 degrees. The highs
tomorrow, with warm morning lows, will push more areas into Major
HeatRisk, especially across the eastern half of the CWA. An
Extreme Heat Warning begins tomorrow for the lower deserts of
Maricopa and Pinal Counties, and the San Carlos area of Gila
County.
Aside from the heat, breezy to locally windy conditions are
ongoing along the lower Colorado River Valley this afternoon.
Winds are a little stronger than originally forecast, with
southerly wind gusts reaching up to 25-40 mph. This is leading to
some widespread hazy conditions from lofted dust and sand and even
may be creating some localized surface visibility reductions from
shallow dust channels. Winds in this area are forecast to
gradually weaken late this afternoon and evening. Thunderstorm
activity the next couple afternoons will remain confined to the
High Country and parts of Southeast AZ, as meager moisture
profiles and increasing subsidence from the strengthening high
will hinder any potential for more widespread convection.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
Wednesday is expected to be peak of the extreme heat episode as
the subtropical high becomes more expansive across the Desert
Southwest and strengthens slightly. This will translate to
widespread high temperatures of 115+ degrees across the lower
deserts with the latest NBM showing a greater than 80% of
occurrence. Temperatures of this magnitude will result in
widespread Major HeatRisk across the majority of the region with
Extreme Heat Warnings in effect across virtually the entire CWA
with exception of the elevations above 4000 feet east of Phoenix
where Heat Advisories are effect. Both Phoenix and El Centro have
a 70% chance of at least tying a daily record high.
The subtropical high is expected to weaken slightly heading into
Thursday as what is leftover from the aforementioned cutoff low
moves eastward through the Great Basin and Intermountain West
Regions, resulting in a suppression of the high. Temperatures are
expected to cooldown slightly but still hot enough for areas of
Major HeatRisk to remain in place with Extreme Heat Warnings
in effect for all of the lower deserts. Heading into the end of
the week and next weekend, the high will continue to slowly
migrate westward towards the southern CA coastline and as a
result heights aloft will continue to decrease slightly. This will
translate to slightly cooler temperatures, enough to drop
readings below extreme heat thresholds but still remain above
normal as afternoon highs will hover around 110 degrees across the
lower deserts.
With the subtropical high stationed over the region and the flow
pattern not favorable for deeper moisture advection into the region,
conditions are expected to remain mostly dry for the next several
days across the majority of the region with any storm potential
to be confined across the White Mountains through the southeastern
third of AZ. In fact, virtually all of the EPS and GEFS ensemble
members do not indicate any measurable rain potential for the
lower deserts until at the earliest the middle of next week when
potentially the subtropical high migrates into the Four Corners
Region, resulting in a more favorable flow pattern for deeper
moisture advection and thus more widespread storm chances.
&&
.AVIATION...Updated at 1720Z.
South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major weather issues will exist through Tuesday morning under
FEW/SCT mid/high cloud decks that will be primarily relegated to
the mountains east of the terminals this afternoon. West winds
will dominate the TAF period. Confidence is moderate to good that
the typical nocturnal switch to east winds will not take place at
KPHX tonight. The typical shift to east/southeast is only expected
at KIWA overnight tonight.
Southeast California/Southwest Arizona including KIPL and KBLH:
No major weather issues will exist through the next 24 hours under
clear skies. Winds will mostly favor SE to S at both terminals,
with a relatively short period of SW winds during the evening for
KIPL.Slightly stronger winds (10-15 kts sustained with gusts up
near 20 kt) anticipated at KBLH this afternoon.
&&
.FIRE WEATHER...
Above normal temperatures will persist throughout the week as
lower deserts highs reach and exceed 110 degrees each day. MinRH
values will generally be in the teens each day, while MaxRH
values will be lowest Tuesday and Wednesday night at 20-40% and
then increase up to 30-50% the rest of the week for most of the
area. The exception will be across Imperial and southern Yuma
Counties where periodic gulf surges will result in MaxRH values in
excess of 50%. The overall wind pattern will follow the familiar
diurnal trends, with some afternoon/early evening breeziness. A
slight uptick in the winds is expected Wednesday and Thursday
afternoon, which may lead to locally elevated fire weather
conditions in the afternoon. Very minimal rain chances will exist
throughout the week with CWR <10% through at least next weekend.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning from 10 AM Wednesday to 8 PM MST Thursday
for AZZ530>533-535-536.
Extreme Heat Warning from 10 AM Tuesday to 8 PM MST Thursday for
AZZ534-537>540-542>544-546-548-550-551-553>555-559-560.
Heat Advisory from 10 AM to 8 PM MST Wednesday for AZZ557-558-
563.
Extreme Heat Warning from 10 AM to 8 PM MST Wednesday for AZZ541-
545-547-549-552-556-561-562.
CA...Extreme Heat Warning from 10 AM Wednesday to 8 PM PDT Thursday
for CAZ560>570.
&&
$$
SHORT TERM...Benedict
LONG TERM...Lojero
AVIATION...Berislavich/Whittock
FIRE WEATHER...Lojero/Benedict