931
FXUS65 KPSR 232321
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
421 PM MST Thu Jul 23 2026

.UPDATE...Updated 00z Aviation Discussion...

&&

.KEY MESSAGES...

- Temperatures much above normal will persist through the weekend
with readings approaching near record levels resulting in Extreme
Heat Warnings.

- The high pressure system responsible for the extreme heat will
also restrict thunderstorm development with chances retreating into
the mountains through the end of the week.

- Temperatures should cool slightly, back to near normal to slightly
above normal, early next week as increased thunderstorm coverage
returns to the region.

&&

.SHORT TERM /Today through Saturday/...
A broad area of high pressure is encompassing much of the southern
US with the ridge axis centered over western CONUS. Additionally,
Tropical Storm Bertha remains just off the coast of Louisiana and is
expected to make landfall later today. With high pressure building
into the region, subsidence is starting to take over along with
dryer air moving into the area. PWATs are around 0.2-0.3" lower than
they were yesterday (current PWATs of 1.4-1.6" across the area).
Despite this, hi-res guidance does show a few isolated showers and
storms popping up over the most favored higher terrain locations
today and tomorrow during the afternoon and evening hours, but
chances remain under 10%. The high pressure will start to migrate
more over the Four Corners region this weekend allowing easterly
waves into our region prompting an increase in shower and
thunderstorm activity across eastern and southeastern AZ. One of the
easterly waves that will move through on Saturday will be the
remnants of Bertha. This wave in particular looks to remain south of
our area and really only influence the activity in SE AZ. Ensemble
members only show minimal moisture transport associated with this
wave, however, it is expected to at least be a forcing mechanism for
activity in SE AZ. While little to no activity is expected across
the lower deserts of south-central AZ, models do support more robust
outflows from these storms reaching the lower-deserts of south-
central AZ which could spark some isolated shower and storm
activity.

H5 heights are around 596 dm over AZ this afternoon. Models remain
in good agreement that the high pressure system will continue to
strengthen, peaking on Friday-Saturday around 597-598 dm.
Temperatures early this afternoon have already reached 113 degrees
at Phoenix Sky Harbor Airport. Temperatures will warm even more
tomorrow and Saturday with afternoon high temperatures forecasted to
reach up to 112-119 degrees across the lower deserts and 100-110
degrees across the higher terrain areas. Morning lows will also be
warm and around 84-94 degrees across the lower deserts and 78-85
degrees across the lower deserts. Temperatures of this magnitude
will easily result in widespread Major HeatRisk with localized areas
of Extreme HeatRisk. An Extreme Heat Warning remains in effect
across the lower deserts for today, Friday, and Saturday and for the
higher elevation valley population centers in Gila County for Friday
and Saturday. Remember to practice smart heat safety by drinking
plenty of water and electrolytes and limiting your time outside,
especially from the late morning through the early evening.

&&

.LONG TERM /Sunday through Wednesday/...
During the first half of next week, the anti-cyclone center will
propagate across the four corners into central Colorado allowing
enhanced easterly flow and better chances of inverted shortwaves
entering the SW Conus. However, there is considerable uncertainty
regarding the timing and location of any particular feature which
would enhance thunderstorm chances, not to mention mesoscale
details from decayed convective complexes which further
complicates the forecast. However, as early as Saturday night,
long tracking, strong outflows may be sufficient to incur isolated
storm development over lower elevations, while deepening moisture
profiles, increasing total column PWATs, and setting the stage
for enhanced convective coverage on following days. Various
modeling suites highlight different days with a more preferred
chance of storms sweeping into lower elevations early next week,
but all models indicate at least one easterly wave influencing
enhanced activity.

This easterly flow will also help erode higher midlevel heights
and temperatures; and combined with the convective influences, may
significantly reduce and complicate heat related impacts. A
growing trend in models shows outflows and convection rapidly
cooling temperatures across Arizona early in the week such that by
Monday, readings return to normal levels. GFS BUFR soundings are
even more aggressive towards outflows affecting temperatures
suggesting extensive cloud cover much of the day Sunday, and
readings falling well short of 110F. Not putting too much stock in
these types of details 3-4 days in advance, but certainly the
pattern supports this evolution where somewhat lower temperatures
and a return to only moderate HeatRisk arrives quicker than
previously forecast.

&&

.AVIATION...Updated at 2315Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation weather concerns under FEW mid to high level
cloud decks are expected throughout the period. The overall wind
pattern will continue to exhibit light, diurnal tendencies with
extended periods of variable conditions.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns under FEW mid to high level
cloud decks are expected throughout the TAF period. Winds will
fluctuate between the southeast to southwest with overall speeds
aob 10 kts. Some gusts between 20-25 kts are likely to materialize
at KBLH Friday afternoon.

&&

.FIRE WEATHER...
Thunderstorm chances will remain quite low the rest of the week with
only slight chances remaining over high terrain areas of far eastern
districts. Better chances for more expansive storm coverage and
wetting rainfall will arrive next week, but minimal activity is
still expected across the lower deserts. Well above normal
temperatures resulting in Extreme Heat Warnings for lower
elevations and foothill locations are expected through at least
the weekend. Despite the warmer and drier conditions, humidity
levels will not fall substantially with minimum afternoon readings
in a 10-25% range improving closer to 15-30% next week.
Correspondingly, overnight recovery will mostly be in a fair to
good range of 30-60% with somewhat higher values next week. Winds
should be fairly light through the period with only local
afternoon gusts 20-25 mph.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Monday for AZZ530>555-559.

     Extreme Heat Warning from 10 AM Friday to 8 PM MST Saturday for
     AZZ556-560>562.

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

&&

$$

SHORT TERM...Berislavich
LONG TERM...18
AVIATION...Lojero
FIRE WEATHER...Berislavich/18