197
FXUS65 KPSR 230456
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
956 PM MST Mon Jun 22 2026

.UPDATE...Updated 06z Aviation Discussion...

&&

.KEY MESSAGES...

- Hotter temperatures this week will result in widespread
  Moderate Heat Risk and localized Major Heat Risk on Wednesday
  and Thursday.

- An Extreme Heat Watch has been issued for portions of the area
  on Wednesday and Thursday with forecast highs between 110 and
  115 degrees across the lower deserts.

- Dry conditions will prevail through the next week with very
  limited chances for isolated showers and a few weak storms mid
  week for portions of Southeast California and Southwest Arizona.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...
A fairly compact, W-E elongated subtropical high remains centered
in the vicinity of El Paso early this afternoon, with zonal flow
in place to its north across much of the Western US. As troughing
in the northern stream continues eastward into the North-Central
CONUS, ensembles remain in excellent agreement that the flattened
subtropical high will amplify/expand, increasing heights aloft
from our southeast. Guidance is in good agreement that H5 heights
will peak late Tuesday into Wednesday, with ensemble mean values
between 595-598 dam, around the 98th-99th percentile of
climatology. This will result in increasing temperatures through
the middle of the work week, with a majority of the typically
hotter spots across the lower deserts expected to near or top 110F
Tuesday afternoon, 3F-6F above daily normals.

As the subtropical high strengthens to our southeast, southerly
flow aloft will become established and import modest midlevel
moisture into the region. Current midlevel water vapor imagery
does indicate a subtle plume of moisture over the Northern
Baja/Gulf of California and offshore, with a collocated
deformation axis and area of upper level diffluence shifting
northward. Moisture may combine with this transient ascent
mechanism to result in isolated shower activity over portions of
the Western CWA late Tuesday, however, PoPs are mostly focused
over Central Riverside County/Joshua Tree NP. The primary impact
from this increase in moisture will be the introduction of
midlevel cloud cover and higher humidity at the surface resulting
in much warmer overnight lows heading into the middle of the week.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
The increasing influence from the subtropical high pushing
temperatures even hotter Wednesday into Thursday will be the main
forecast concern later this week. The latest NBM forecast
temperatures have bounced back from the slight dip with
yesterday`s guidance with the bulk of the lower desert showing
highs between 111-114 degrees for both Wednesday and Thursday. The
increase in low level moisture will also lead to much warmer
overnight lows with readings only dipping into the low to mid 80s
for much of the area to as warm as the upper 80s to around 90
degrees for much of the Phoenix metro. Due to the building heat,
we have issued an Extreme Heat Watch for portions of the area,
including Phoenix, Yuma, and El Centro for Wednesday and Thursday.

An upper level trough will slide southeastward into the
Northwestern U.S. starting Wednesday and eventually closer to our
region by Friday. This feature will help to lower heights across
our region starting Thursday, but there will be a noticeable lag
to any decent cooling. Forecast highs Friday are still between
110-113 degrees, but overnight temperatures should cool off more
quickly due to the expected drier air that will work into the
area from the west starting on Friday. The trough to our north
should really start to influence our region by the coming weekend,
knocking down H5 heights more into a 585-588dm range Saturday to
as low as 582-585dm on Sunday into next Monday. NBM forecast highs
are shown to dip into or even a few degrees below normal by
Sunday. The main forecast concern will turn away from Extreme Heat
Friday into the coming weekend and more toward breezy to locally
windy conditions causing critical fire weather concerns.

&&

.AVIATION...Updated at 0455Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation weather concerns expected throughout the TAF period.
The overall wind pattern will follow the typical diurnal
tendencies with speeds aob 10 kts along with some occasional
afternoon/early evening gusts in the mid to upper teens. There is
a bit of uncertainty of whether or not a full easterly shift
materializes overnight tonight into early Tuesday morning,
especially at KPHX, with the potential for variable directions to
be more prominent. Nevertheless, a full westerly shift should
materialize by the mid to late morning hours. Clear skies will
prevail into Tuesday morning before some mid to high clouds move
in during the afternoon/evening hours.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns can be expected throughout the
TAF period. At KIPL, winds will generally be out of the southeast
while at KBLH, winds will generally be out of the south. Some
gusts between 20-25 kts can be expected at KBLH once again Tuesday
afternoon. Clear skies will prevail into Tuesday morning before
some mid to high clouds move in during the afternoon/evening
hours.

&&

.FIRE WEATHER...
Locally elevated fire weather conditions due to very low humidity
and afternoon upslope/upvalley breeziness will continue through
the middle of the week. Afternoon minimum humidities will improve
slightly into a 10-15% range starting Tuesday, however, there will
be little to no improvement in overnight recoveries as they
remain mostly poor between 15-35%. Temperatures will heat up into
an above normal category for much of the week with lower desert
highs topping 110 degrees at least on Wednesday and Thursday, and
overnight lows will offer little relief as they rise into the 80s
for much of the lower deserts. Winds will remain generally terrain
driven through the middle of the week with upslope/upvalley gusts
between 20-25 mph during the latter half of the afternoon into
the early evening. Areas of critical fire weather conditions look
likely by Friday or Saturday as southwesterly winds increase
across the region.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Watch from Wednesday morning through Thursday
     evening for AZZ530-532-533-537-540-542>544-546-548-550-551.

     Extreme Heat Warning from 11 AM Tuesday to 8 PM MST Wednesday
     for AZZ560.

CA...Extreme Heat Watch from Wednesday morning through Thursday
     evening for CAZ562-566-567-569.

&&

$$

SHORT TERM...Whittock
LONG TERM...Kuhlman
AVIATION...Lojero
FIRE WEATHER...Whittock/Kuhlman

NWS Phoenix (PSR) Office