459
FXUS65 KPSR 071126
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
426 AM MST Fri Aug 7 2026

.UPDATE..Updated 12z Aviation Discussion...

&&

.KEY MESSAGES...

- Extreme heat conditions will continue through the weekend, with
  afternoon highs hovering near to several degrees above normal
  while humidity values remain higher than normal.

- Shower and thunderstorm activity will be confined to higher
  terrain areas and Southeast Arizona through at least the start
  of the weekend with gusty outflow winds and blowing dust the
  most likely impacts for lower elevations of South-Central
  Arizona.

- Monsoon rainfall chances begin to expand into the lower deserts
  by late this weekend and into the start of next week.

&&

.SHORT TERM /Today through Saturday/...
Current objective analysis reveals broad anti-cyclonic flow over the
Great Basin and Four Corners regions, helping to keep parts of
Arizona active with convective activity. After yesterday, in which
Southeastern and Southern Arizona saw widespread severe weather, the
atmosphere down there was incredibly worked over, limiting
thunderstorm coverage and allowing northern portions of the state
become the main focus for monsoon storms. Meanwhile, the lower
deserts of South-Central Arizona remain quiet, not because the
ingredients are not there, but rather a strong cap has been in
place, and there has not been any significant triggering mechanisms
to tap into available elevated instability. Model soundings point
towards a weaker cap across the eastern half of our coverage area,
so perhaps we see a bit more convective coverage for the population
centers of Maricopa and Pinal Counties. However, PoPs do not project
much optimism as rain chances remain at 15% or less. It would likely
require a strong enough outflow to set off any convection over these
areas, and as of now, guidance does not favor that outcome. However,
this does not completely rule out lower elevation activity, as there
are some hints amongst the hi-res data that favor a more active
result. Regardless of all this, typical orographically induced
shower and thunderstorms can still be expected for areas to the
north and east of the Phoenix metro.

Even though the high will remain in a favorable position for
continued monsoonal activity, Saturday may turn out out to be a bit
of down day compared to what we have seen across Arizona this week.
The reason for this downtrend will be the introduction of drier air
originating from the Rockies where PWATs are running well below
normal for this time of year (about 30-60%) of normal. The easterly
flow that usually provides the region the moisture needed to get our
seasonal rains will do the opposite for a time and erode at the
moisture that is currently in place. PWATs for Eastern and Central
Arizona will fall to around 70-90% of normal, which should greatly
inhibit storm activity. Convection should not completely cease, but
coverage should be focused primarily around the most enhanced
terrain features. NBM PoPs do appear to reflect this scenario as
rain chances are on par with chances for this afternoon, even though
moisture profiles will be much better today. Therefore, PoPs have
been lowered slightly for Saturday afternoon and evening.

The sub-tropical high will continue its trek eastward through the
near term, peaking at 594-597dm as it migrates. These heights aloft
are above the 90th-95th percentile for this time of year, indicating
a very warm airmass throughout the column for this time of year,
even for our standard. Now, this does not mean we are expecting
record breaking temperatures, but afternoon highs will run a good 4-
8 degrees above normal for early August, translating to readings
ranging near 107-115 degrees. As a result, high-end Moderate to
Major HeatRisk remains in the forecast and the Extreme Heat
Warning will remain in effect during this timeframe.

&&

.LONG TERM /Sunday through Thursday/...
The relative pause in convective activity should be fairly short
lived as the high will eventually become parked over the Four
Corners, inducing southeasterly flow over the region which should
provide renewed moisture flux. PoPs have fallen slightly compared to
24 hours ago, mainly for lower elevation areas, but that is not much
of a surprise as it make take a little bit more time to get moisture
profiles back to more favorable levels. The more favorable spots to
see convection will once again be the High County and Southeast
Arizona, but downstream effects from any activity that does form
could have impacts on our lower elevation zones. Once we get
closer, and get inside the hi-res window, we will have a better
idea on what impacts to expect.

Daily chances for shower and thunderstorms will reach into the front
half of the next workweek as sufficient moisture stays in place. The
lower deserts, if not by Sunday, may finally get in on some of the
action as low-level moisture looks to improve with model soundings
indicating mixing ratios reaching 11-12 g/kg. That will aid in
increasing instability and limiting the cap that has been so
prevalent the past few days. As typical with the monsoon, how one
day plays out will heavily influence what happens the subsequent
day, so day-to-day forecast changes should be expected, but with
moisture levels not likely to fall off through at least the middle
part of the week, we may be looking at one of the more active
periods we have seen so far this summer.

Temperatures will remain several degrees above seasonal levels
through Sunday, but there appears to be at least some relief on the
horizon. With increased moisture, storm coverage, and cloud cover,
afternoon highs over South-Central Arizona are expected to fall much
closer to normal for this time of year with projected lower-desert
highs between 101-106 degrees by Tuesday. Areas further displaced
from the storm activity, namely Southwest Arizona and Southeast
California, will see temperatures gradually decrease too thanks to a
weakening trend with the prevailing high, but readings should remain
slightly higher relative to locations further east. Highs for those
western desert locations will be closer to 105-110 degrees through
at least Thursday.

&&

.AVIATION...Updated at 1120Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Outflow winds and slight potential for thunderstorm activity this
evening will be the main aviation weather challenges during the
upcoming TAF period. In the meantime, conditions will remain
relatively tranquil through this afternoon with light easterly
winds to variable conditions prevailing through the early morning
hours before the typical westerly shift materializes mid to late
morning. Some occasional afternoon gusts in the mid to upper teens
will be possible. Heading into this evening, thunderstorm activity
across the higher terrain to the north and east may approach the
Phoenix metro, mostly likely after 02-03z, however, confidence of
any direct impacts is low at this time with the more likely
outcome that the activity dissipates before reaching the
terminals. There will be higher potential for an outflow boundary
to move through, shifting the winds out of the east to northeast.
SCT-BKN mid to high clouds will prevail through early this morning
before coverage decreases to FEW late morning through the
afternoon. Cloud coverage will increase to SCT-BKN once again this
evening.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns under FEW to occasionally SCT mid to
high-level cloud decks can be expected throughout the TAF period.
At KIPL, southeasterly winds will prevail through this afternoon
with a westerly shift likely this evening. At KBLH, winds will
generally fluctuate out of the south to southwest. Overall speeds
will remain aob 10 kts.

&&

.FIRE WEATHER...
Hot temperatures with relatively elevated humidity levels will
continue through the weekend. Though afternoon RHs do trend
downward through Saturday, regional readings should remain at 15%
or above into next week. Overnight recovery will offer modest to
decent relief as MaxRHs range generally between 30-55% through
Sunday, with even better readings expected by next week. Rain
chances through Saturday will be mostly confined to high terrain
areas and southeastern Arizona, with lower desert chances
remaining 15% or below. By Sunday, increasing moisture will
result in an uptrend in lower elevation shower and thunderstorm
chances, which appears likely to persist into the following week.
Outside of thunderstorm outflows, winds will follow familiar
diurnal trends, with typical afternoon upslope breeziness around
20 mph.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Sunday for AZZ530>544-546-
     548>551-553>555-559.

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

&&

$$

SHORT TERM...RW
LONG TERM...RW
AVIATION...Lojero
FIRE WEATHER...RW