213
FXUS65 KPSR 042010
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
110 PM MST Tue Aug 4 2026

.KEY MESSAGES...

- Extreme heat will persist through the end of the week with
temperatures hovering near to several degree above normal.

- Shower and thunderstorm chances will favor east and southeast
Arizona the remainder of the week with gusty outflow winds and
blowing dust the most likely impacts for south-central Arizona.

&&

.SHORT TERM /Today through Thursday/...
Elongated subtropical ridging was meridionally bisecting Arizona
this afternoon with a H5 594dm anti-cyclone center over western New
Mexico. This configuration was confining shortwaves in enhanced
easterly flow over northern Sonora with very weak flow and more
neutral ascent structure closer to the high pressure core covering
the CWA. Despite strong thunderstorm outflows importing 11-12 g/kg
boundary layer mixing ratios into the majority of the forecast area
this morning, exceptionally warm air at the top of the mixing depth
has contributed to strong inhibition with forecast CinH in excess of
100 J/kg the remainder of the day. As a result, it would require
multiple deep outflow boundaries to release instability this
afternoon/evening, and little to no modeling suggests more than
residual, isolated midlevel showers/virga. Instead, another round of
gusty outflow winds emanating in far southern Arizona will be
possible mid/late evening across south-central Arizona, though the
magnitude and extent of impacts appears less than Monday.

The synoptic trend over the next 72 hours is towards the migration
of the anti-cyclone center into southern Utah while increasing in
both magnitude and breadth as the H5 core approaches 600dm. While
this northward shift would tend to support increasing convective
chances with cooler lower/middle tropospheric temperatures and
increased easterly flow, the strengthening anti-cyclone will
generally negate these tendencies imparting growing subsidence and
expansion of the warm core aloft. This will create an ebbing effect
on both temperatures and convective potential. Afternoon highs
should retreat closer to daily normals Wednesday with only minor to
moderate HeatRisk, but then quickly resume a warming trend Thursday
as areas of major HeatRisk re-emerge. Similarly, thermodynamic
conditions appear slightly more favorable for thunderstorm
development across lower elevations Wednesday afternoon/evening as
CinH likely drops below 50 J/kg where multiple, colliding outflows
could breach this inhibition. Surprisingly, nothing in the HREF
suite supports lower elevation storms resulting in very low POPS,
but it wouldn`t be unexpected if somewhat better chances
materialize.

&&

.LONG TERM /Friday through Monday/...
Little will change with the weather pattern for the rest of this
week, and likely well into next week as the high pressure ridge is
expected to remain centered over the Desert Southwest. The center of
the ridge is forecast to somewhat shift farther to the north by
Friday which could help to bring better rain chances, but guidance
shows the ridge also strengthening which will likely reinforce the
subsidence over much of our area. As of now, Friday is expected to
follow the same pattern as today and Wednesday with mostly eastern
Arizona high terrain storms and very conditional 5-15% PoPs into the
south-central Arizona lower deserts. As stated in the short-term
discussion, even though it will be a day-to-day low chance
environment for the lower deserts, it would not be surprising to
have a day where the elevated instability is managed to be tapped
into causing some scattered storms to fire. Hot and humid conditions
will continue to prevail with daytime highs likely nudging upward
again late week as the ridge restrengthens. The Extreme Heat Warning
currently goes through Friday which is very reasonable, but it will
be possible to have a day in there where it fails to reach criteria
over south-central Arizona if convection ends up being more
widespread one evening/overnight.

For the weekend into early next week, ensembles still favor the
ridge basically staying stationary with the center somewhere just to
our north. Some weakening of the ridge is likely to occur by early
next week and depending on how much moisture will be available we
could be looking at a further uptick in monsoon activity. The GEFS
is more optimistic with rain chances by early next week with
activity expanding into central and northern Arizona, but the EPS
holds off until later next week. If convection does eventually
become more widespread and impacts the lower deserts, temperatures
are expected to dip closer to seasonal normals.

&&

.AVIATION...Updated at 1715Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT;
The main aviation concern during the TAF period will be gusty
outflow winds and reduced VIS due to blowing dust late this evening
into early Wednesday morning. For starters, there remains some light
visibility restrictions from lingering dust from last night, with
some local 4-6SM, but this should continue to mix out this
afternoon. Winds are expected to follow diurnal trends, with the
switch to westerly winds this afternoon with some late afternoon
gusts to 20kts. Another outflow boundary is expected to move in from
the south/southeast sometime between 06-10Z based on current
forecast trends. Associated gusts may reach upwards of 30 kt, and
with the orientation of the boundary, another round of blowing dust
is certainly not out of the question. However, this outflow will be
heavily conditional upon how distant convection over southeast
Arizona evolves, so adjustments and amendments should be expected.


Southeast California/Southwest Arizona including KIPL and KBLH: :
Breezy conditions, mainly at KBLH, will be the main aviation concern
during the TAF period. There, winds will favor a S`rly direction
through the forecast, with gusts during the afternoon around 20-25
kt. Winds at KIPL will be much weaker, generally ranging 7-15 kt out
of the SE. FEW to occasionally SCT high level clouds will be present
through the majority of the forecast window.

&&

.FIRE WEATHER...
Hot temperatures will continue all week with fairly elevated
humidities, but showers and thunderstorms will mostly remain over
far eastern and southeastern Arizona. Gusty outflow winds are likely
to impact the south-central Arizona lower deserts again late this
evening. MinRHs will continue to improve, climbing to around 25-30%
by Wednesday, while overnight recoveries range between 40-70%.
Outside of storm outflows, winds will mostly follow diurnal
patterns, but southwesterly winds will be dominant much of the time
with afternoon gusts of 15-25 mph at times.

&&

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

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

&&

$$

SHORT TERM...18
LONG TERM...Kuhlman
AVIATION...Lojero/Frieders
FIRE WEATHER...Kuhlman

NWS Phoenix (PSR) Office