340
FXUS65 KPSR 312253
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
353 PM MST Fri Jul 31 2026

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

&&

.KEY MESSAGES...

- Extreme heat will persist over the region through at least the
  weekend temperatures topping out around 115 degrees and above
  over much of the lower deserts, hovering right around record
  levels.

- In response to the very hot conditions, Extreme Heat Warnings
  are in effect regionwide now until Monday.

- Drier air over the region will confine any chances for showers
  and thunderstorms over far eastern Arizona high terrain areas
  through at least Monday.

&&

.SHORT TERM /Today through Sunday/...
Extreme heat continues to be the main forecast point during the
near term as the sub-tropical high continues to strengthen.
Current RAP analysis indicates associated atmospheric heights
have now reached upwards of 598-600dm, making this instance of the
anti-cyclone one of the strongest all time for this time of year,
according to climatology. With this type of intensity, and with
relatively dry air in place, at least for the monsoon season,
allowing for more efficient surface heating, daily high
temperatures between 110-118 degrees will be common across the
lower deserts through at least Sunday. Probabilities of reaching
120 degrees across parts of southwest Arizona and southeast
California have come down over the past few days, but reaching
that threshold cannot be completely ruled out as some low end
chances (<30%) remain, mainly for locations around the Lower
Colorado River and Imperial Valleys. Overnight lows will not offer
much relief as readings will bottom out only into the middle 80s
to low 90s. As a result of these temperatures, Extreme Heat
Warnings will continue regionwide for the next several days.

With the sub-tropical high now positioned directly over Arizona,
increasing regional subsidence, and the above-mentioned dry air in
place, monsoon shower and thunderstorm activity will be heavily
inhibited through at least this weekend. Best rainfall chances
will be confined to the White Mountains and portions of
southeastern Arizona, where somewhat better moisture can be found.
It looks the only chances to see convection within our CWA
boundary during this time frame will be for far southeastern Gila
County, but probabilities only max out at around 10-20%.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
The ridge is forecast to weaken Sunday into Monday with H5
heights dropping to 594-596dm or right around the 90th percentile
of climatology. Despite the ridge weakening, the residual heat
dome will take some time to cool as forecast highs Monday only
drop a couple degrees from Sunday`s readings, keeping the HeatRisk
at Major to Extreme for much of the area. As the ridge weakens
and also shifts its orientation some, moisture should begin to
increase again across southeast Arizona on Sunday and then
eventually over all of southern and central Arizona Monday into
Tuesday. As a result, convective potential will tick upwards early
next week, first over the Arizona higher terrain and eventually
into the lower deserts during the middle part of next week. The
expected increase in convection is likely to help to cool things
off Tuesday into Wednesday, dropping the HeatRisk into a high-end
Moderate to low-end Major. There is still a good amount of
uncertainty as far as the storm chances during the first half of
next week, so any delay in the moisture may result in having to
extend the Extreme Heat Warning another day or so for portions of
the area.

&&

.AVIATION...Updated at 2250Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation weather concerns under FEW-SCT mid to high-
level cloud decks can be expected throughout the TAF period.
Generally westerly winds will prevail throughout the TAF period,
although a period of light easterly to variable conditions are
likely early Saturday morning. Some occasional gusts in the mid to
upper teens are likely through early this evening and once again
for Saturday afternoon/early evening.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns under some passing high cirrus
cloud decks can be expected through the TAF period. Winds will
mostly prevail out of the southeast at KIPL and will vary between
the southeast and southwest at KBLH. Overall wind speeds will
generally remain aob 10 kts, with some occasional gusts into the
mid to upper teens, mainly at KBLH.

&&

.FIRE WEATHER...
Strong high pressure will persist over the region through the
weekend while relatively dry air confines any rain chances to
over far eastern Arizona. Expect daily MinRHs mostly between
10-15%, while falling overnight RHs offer only little to modest
relief. Record to near record temperatures are also forecast today
and through the weekend. Winds will mostly follow diurnal
patterns, but west southwesterly winds will be dominant much of
the time with afternoon gusts of 15-20 mph at times.

&&

.CLIMATE...
Record high temperatures:

Date       Phoenix         Yuma         El Centro
----       -------         ----         ---------
Jul 31   116 in 2020    119 in 1957    119 in 2020
Aug 1    116 in 1972    117 in 1993    118 in 1993
Aug 2    114 in 2025    117 in 1918    117 in 1969
Aug 3    116 in 2024    116 in 1998    117 in 2021

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Monday for AZZ530>563.

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

&&

$$

SHORT TERM...RW
LONG TERM...Kuhlman
AVIATION...Lojero
FIRE WEATHER...Kuhlman
CLIMATE...18