099
FXUS65 KPSR 280852
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
152 AM MST Tue Jul 28 2026

.UPDATE...

Updated Aviation

&&

.KEY MESSAGES...

- Above normal temperatures will continue through the forecast
period with Extreme Heat Warnings in effect for portions of the area
through mid week.

- Typical monsoon conditions will continue for the next few days
with thunderstorm chances favoring Northern Arizona high terrain and
portions of Southeast Arizona and low chances in the South Central
Arizona lower deserts.

- High pressure will center itself over the region and strengthen
late this week, resulting in hotter temperatures and another period
of widespread Major to Extreme Heat Risk.

&&

.SHORT TERM /TODAY THROUGH SATURDAY/...

A MCV can be seen on GOES mid-lvl WV imagery along with a large
plume of moisture surging over Northern Mexico and southeastern AZ.
This system is expected to track through south-central AZ through
the overnight and early morning hours, with some isolated embedded
showers already seen in southern Graham County moving
northwestwards. This system will help the atmosphere regain some
moisture with this morning forecasted PWATs between 1.7-1.9", and
mixing ratios between 12-14 g/kg. Additionally, forecasted MUCAPEs
throughout the morning are between 500-1000 J/kg across most of the
lower deserts and upwards of 1500 in the eastern high terrain. Hi-
res CAMs have also picked up on these conditions and is projecting
morning thunderstorm/showers mostly in the eastern higher terrain
but a few isolated thunderstorms/showers will be possible across
southcentral AZ. By the afternoon moisture and CAPE values across
south central AZ is expected to decrease, however the higher terrain
will hold onto their moisture and instability with afternoon mixing
ratios remaining above 12 g/kg and MUCAPEs upwards of 1500 J/kg.
This will keep chances for thunderstorms and shower activity across
the eastern higher terrain between 15-30%. The HREF only shows about
a 10% chance of an outflow being produced out of the southeast, with
winds above 35mph, this is in decent agreement with other models,
such as the HRRR, where peak gusts this morning are forecasted
between 20-25 mph. Increased chances of outflows will be this
afternoon from the NE from storms in the higher terrain, where the
HREF shows a 10-30% chance of winds above 35 mph, however many other
models are currently not in good agreement with any outflows being
able to extend down into Maricopa County.

Starting Wednesday thunderstorm activity is expected to decrease
drastically as the region will begin to dry out and an exceptionally
strong ridge builds over the Desert SW. By mid week PWATs will drop
to between 1.4-1.6", then progressively lower to between 1-1.3" by
Friday. This drying will be accompanied with near to at
climatological max H5 heights (600 dam) that will drive temperatures
back to near record highs by the end of the work week and into the
start of the weekend. Temperatures will be fairly stable through
midweek, especially across the western deserts, with afternoon highs
in a 110F-114F range, between 2F-8F above daily normals for the
typically hotter spots and today likely being the "coolest" of the
next 7 days. The Phoenix metro will thankfully be a few degrees
"cooler" compared to the western deserts, with afternoon highs today
between 107F-110F. These temperatures are still above 4-6 degrees
above normal, before steadily climbing throughout the remainder of
the week. Friday and Saturday will be the hottest days this week
with temperatures in south central AZ between 112F-117F, while the
western deserts will be between 113F-120F. Overnight lows won`t
provide much relief either as throughout the week they will hold
steady in the upper 80s to low 90s. These temperatures will
produce wide spread Major to Extreme HeatRisk, which has lead to
the decision to extend the Extreme Heat Warning for the Phoenix
metro, Imperial Valley, and the Lower Colorado River Valley
through Sunday, and expanding the Extreme Heat Warning to include
the rest of the region starting Thursday, also going through
Sunday.

&&

.LONG TERM /SUNDAY THROUGH TUESDAY/...
By the end of the of the weekend and heading into the next work
week, global ensembles point towards H5 heights weakening slightly
to between 594-597 dams, and the center of the anticyclone over
AZ, stretching into the Four Corners region. Although these
heights will still remain above the 90th percentile of
climatology for this time of year, resulting in temperatures
remaining between 110F-114 in south central AZ, and the western
deserts between 113F-117F. Widespread Major to Extreme HeatRisk
will continue through Sunday, Major to localized Extreme Monday,
and Moderate to localized Major by Tuesday. By Sunday moisture
will begin to increase once again, with easterly to northeasterly
flow aloft which will have potential for increased chances of
thunderstorm development in northeastern AZ, with current PoPs
between 20-30% in eastern Gila County. Unfortunately, with this
outlook being so far in advanced conditions may change, so further
evaluation will be needed throughout the week.

&&

.AVIATION...Updated at 2300Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Some minor uncertainty in wind direction will be the only forecast
challenge through Tuesday evening under periods of thicker midlevel
cloud decks with thunderstorms remaining over mountains of eastern
Arizona. Confidence is good that west winds with modest gusts will
prevail much longer into the evening/overnight than usual. Most
evidence suggests KPHX never going easterly (variable, at best)
overnight with only partial decoupling. While BKN midlevel cigs
Tuesday morning may complicate wind trends, evolution should be
similar to today.

Southeast California/Southwest Arizona including KIPL and KBLH:
Occasionally gusty wind will be the only weather concern through
Tuesday evening under passing mid/high clouds. Confidence is good
that wind directions will oscillate between SE and SW at KIPL while
a southerly component will be preferred at KBLH. Gusts around 20 kt
will be common at KBLH during the afternoon.

&&

.FIRE WEATHER...
Typical monsoon conditions are expected through much of the
forecast, with thunderstorm activity mainly favoring the high
terrain of northern AZ and southeastern AZ and low chances (544-546-548-550-551.

CA...Extreme Heat Warning until 8 PM PDT Wednesday for CAZ567-569-570.

&&

$$

SHORT TERM...Ryan
LONG TERM...Ryan
AVIATION...18
FIRE WEATHER...Ryan

NWS Phoenix (PSR) Office