377
FXUS65 KPSR 251842
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1142 AM MST Sat Jul 25 2026

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- Much above normal temperatures will continue through the
  weekend with readings approaching near record levels and Extreme
  Heat Warnings in effect.

- Strong outflow boundary winds will move through south-central
  Arizona late this afternoon and evening, with a slight chance to
  generate showers and and storms over the lower deserts.

- Temperatures will cool slightly early next week as high pressure
  weakens, but will rise again heading into the latter half of the
  week with widespread Major and areas of Extreme heat risk
  returning.

- Typical monsoon conditions are expected next week with daily
  thunderstorm chances favoring northern Arizona high terrain and
  southeast Arizona and low chances in the south-central Arizona
  lower deserts.

&&

.SHORT TERM /Today through Monday/...
The temperature at midnight in Phoenix was 107 degrees, which is
quite frankly disgusting and very unpleasant. This is not the
first time though that temperatures were this hot in the midnight
to 1 AM hour. The temperature was 107 at midnight back on July
30th, 2023 and was nearly as hot during the middle of the same
month, when the 97 degree record warm low was first set. There is
a decent chance to break the all time record warm low this
morning, especially considering the record was tied yesterday
morning and the temperature shortly after midnight this morning
was 3-4 degrees warmer than the same time yesterday morning.
Whether the record is broken is largely dependent on the winds. If
a westerly breeze can be maintained through sunrise, then the
record will probably be broken and it is not out of the realm of
possibility to see the first 100 degree low.

After another hot morning temperatures this afternoon will again
heat up to similar levels to yesterday, if not 1-3 degrees hotter,
with lower desert highs forecast to reach 114-119 degrees. This
combo of forecast record warm lows and near record highs is
leading to widespread Major HeatRisk and areas of Extreme HeatRisk
in the most populated areas. Combining this with the weekend only
increases the already heightened risk for heat-related health
impacts. Even the morning hours are not recommended for outdoor
recreation given the very hot start and rapid warming through the
morning - 110 degrees by 11 AM. The mugginess, dew point
temperatures in the upper 50s to 60s will only add to the
discomfort. While not much, there will be a small degree of
relief to the temperatures, at least with the highs, heading into
Sunday and Monday as H5 heights come down a few decameters and
850mb temps cool a few degrees C. The mornings will remain
uncomfortable with lows in the upper 80s to low 90s. High
temperatures Monday are forecast to drop to within a few degrees
above normal, but the added humidity may add a few degrees onto
the early afternoon apparent temperatures. So, for now the
Extreme Heat Warning will be maintained through Monday.

The prospect of showers and thunderstorms in the lower deserts of
South-Central AZ are slightly better today-tonight than they were
the past few days, for a few factors coming together. Broad
anticyclonic flow remains in place across the Desert Southwest,
with an IT (Bertha remnants) seen moving across Sonora, MX this
morning and there is a small mesoscale low pressure over central
NM. Latest guidance shows the mesoscale low will progress into
east-central AZ this afternoon and evening, assisting Rim
convection and inducing a light east-northeast steering wind off
the Rim. DCAPE will be fairly high today across South-Central AZ
(1200-1800 J/kg), given the very hot temperatures, and latest
HREF favors moderate to strong outflows (30-50 mph wind gusts)
moving off the Rim into the lower deserts in the late afternoon
and evening. It remains to be seen if the outflows will generate
new storms over the lower deserts or if the cap/CIN will will be
too much to overcome. Even if it is overcome, showers and storms
over the lower deserts are not expected to be too intense, due to
sub-1000 J/kg CAPE, owing to the very warm air aloft and deep
boundary layer. The strongest storms today will be around Tucson
and points south, where moisture and instability will be greatest,
with modest shear (20-25 kt) as well. These storms will likely
push outflows north-northwestward toward South-Central AZ later
in the evening, which may collide with the southwestward-moving
outflows to spark activity. Mid and upper level ascent will
increase heading into the overnight hours tonight, to perhaps
support lingering showers during the night, as an upper level jet
streak nudges in from the east.

Heading into Sunday and Monday, the synoptic setup will take on
more of a traditional monsoon regime with high pressure centered
to the northeast and increasing southeast flow. Storms will
primarily focus over N AZ and SE AZ, with the strongest storms
still near the international border. Despite an increase in
boundary layer moisture (11-12 g/kg mixing ratios) and
instability model soundings show a moderate-strong capping
inversion that may be difficult to overcome for convection to
ensue over the lower deserts, away from terrain features. Latest
NBM has 10-20% chances in Maricopa and northern Pinal counties
Sunday and Monday.

&&

.LONG TERM /Tuesday through Friday/...
Strong, expansive ridging will remain nearly in place through next
week across the southwest and central United States with the
anti-cyclone center rotating back from central Colorado into New
Mexico and Arizona. Early in the week, sufficient easterly flow
will prevail over the region juxtaposed with marginally supportive
mixing ratios of 9-11 g/kg for scattered storms. There remains
considerable uncertainty regarding a more preferred time frame for
higher POPS in any given location with mesoscale details likely
becoming more important towards convective evolution. Overall,
this appears to be a very typical monsoon pattern with alternating
convectively active and inactive days. However, by the latter
half of the week, there are a handful of NAEFS members indicating
notable strengthening of the high pressure with 600dm H5 heights
materializing and the center of the anticyclone shifting to over
northern AZ/southern UT. It appears the NBM/WPC forecasts are
latching onto this scenario as POPs dwindle to much lower than
expected values given the ensemble mean synoptic pattern. The
larger impact of this outcome would be a return to major HeatRisk
and extreme heat thresholds towards the end of the week, after the
very short-lived reprieve at the beginning of the week. As a
result, the current Extreme Heat Warning may actually be extended
as one prolonged warning event.

&&

.AVIATION...Updated at 1842Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Gusty winds with the potential for multiple wind shifts this
evening/overnight will be the main weather issue through the
period with occasional passing mid/high level cloud decks
potentially lowering and becoming thicker this evening. Confidence
is high that at least one outflow boundary will move through the
metro this evening with gusty winds (25-30 kt, 50% chance of some
gusts in excess of 35 kt). Confidence is lower on how many
outflows will move through the metro, from which directions, and
if they will be carrying any BLDU leading to reduced VIS. Models
continue to show a NE`rly outflow arriving between 00-01Z this
evening. Models also hint at an additional SE`rly outflow will try
to make it into the metro a couple hours later, however they show
the NE`rly outflow dominating over the SE`rly outflow. If the
NE`rly outflow dominates this evening, as currently expected, then
little to no reductions in VIS are expected from BLDU. However, if
a SE`rly outflow can make it into the metro BLDU and reduced VIS
will become more of a concern, depending on the strength of the
outflow. The possibility of SHRA/TSRA behind the wind shift
remains around 20% and therefore has not been included in the TAF.
If there are multiple colliding outflows over the metro,
confidence will increase. Confidence is low on the wind direction
after the outflow moves through the metro. Currently looks like
winds will southerly during the overnight hours before going
SE`rly early tomorrow morning.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major weather issues will exist through Sunday morning under
occasional passing mid/high cloud decks. Wind patterns will be
nearly identical to the past 24 hours, generally oscillating
between SE and SW. Gusts may be more prevalent at KBLH this
afternoon. May have to watch for an additional period of gusty
winds at KBLH during the overnight hours. It will depend on if an
outflow can make its way into the area.

&&

.FIRE WEATHER...
There will be better chances for showers and storms this weekend
into early next week, than the previous few days, but with
activity still mostly favoring the high terrain of northern AZ and
southeastern AZ and slight chances (10-20%) in the lower deserts
of south-central AZ. There is high confidence that strong gusty
thunderstorm outflow winds will progress into the lower deserts
late this afternoon and this evening, which may offer slightly
better odds for rain over the lower deserts today than in the
following few days. Extreme, well above normal, temperatures will
contribute to seasonally dry afternoon conditions. Hottest
temperatures will be today, with minimum afternoon RH values in
the 10-20%. Temperatures then fall several degrees heading into
the beginning of next week and moisture increase slightly, leading
to minimum RH values improving slightly to 20-30%. Temperatures
will warm back up again during the latter half of next week and
minimum RHs will again fall to the 10-25% range. Overnight
recoveries will be fair most nights with RH values mostly in the
35-50% across lower deserts to 45-65% across southern Gila
County. Daily afternoon thunderstorms will continue through next
week, mostly across higher terrain and outside of thunderstorm
outflows, wind speeds 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 until 8 PM MST this evening for AZZ556-
     560>562.

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

&&

$$

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