133
FXUS65 KPSR 011705
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1005 AM MST Fri Aug 1 2025

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- Hot temperatures with lower desert highs of around or just over
  110 degrees will continue to persist with at least widespread
  Moderate HeatRisk each day.

- Extreme Heat Warnings with areas of Major HeatRisk will affect
  portions of south-central AZ today and Saturday.

- Another more widespread Extreme Heat episode is expected mid to
  late next week, with record high temperatures possible along
  with Major to locally Extreme HeatRisk.

- Overall dry conditions will prevail for much of the area with
  limited chances of showers and storms mainly over eastern
  Arizona today and possibly again early next week.


&&

.SHORT TERM /Today through Saturday/...
Moisture ticked upward a bit yesterday with some fairly minimal
shower and thunderstorm activity across the Arizona lower deserts,
lasting into the early overnight hours across eastern portions of
the Phoenix metro. However, drier air is already working its way
eastward across western Arizona, expected to spread over the rest
of the area by this afternoon. This should end rain chances
across the lower deserts with only a few showers or a weak storm
possible this afternoon across far eastern Arizona.

The subtropical high has also begun to recenter itself across
southern Arizona, while also strengthening through early Saturday
pushing H5 heights upwards of 598dm. The boundary layer will still
contain some elevated moisture levels today and this will somewhat
contain temperatures, but the lower deserts are still forecast to
reach between 109-112 degrees. As we continue to lose our surface
moisture going into Saturday, highs may increase by another
degree or two. Both today and Saturday will present localized
areas of Major HeatRisk across the south-central Arizona lower
deserts with the Extreme Heat Warning going into affect late this
morning and lasting into Saturday evening. NBM probabilities show
an 80% chance of tying the record high of 113 degrees in Phoenix
on Saturday.

&&

.LONG TERM /Sunday through Friday/...
The main forecast concern in the long term will be the building
heat during the middle to latter part of next week with record
temperatures likely to occur. Initially, we will get a little bit
of a break by Sunday with overnight lows improving due to the
drier air and H5 heights lowering a smidge. This should drop lows
back to around normal which would be as much as five degrees
lower in Phoenix compared to current lows. Daytime highs are still
forecast to top out between 108-112 degrees each day through
early next week, but when combined with the cooler overnight lows
it will drop the entire area into the Moderate HeatRisk category.

The center of the ridge is eventually expected to shift eastward
into New Mexico Monday into Tuesday allowing for some weak south
southeasterly flow into Arizona. Guidance does show some moisture
return into the area during this time, but PWATs are only shown
to max out at around 1.1" with low level mixing ratios at most
between 7-9 g/kg. This may bring a few isolated showers or a weak
thunderstorm already on Monday, but chances seem a bit better (but
still limited) on Tuesday with a bit better moisture.

The ridge is also forecast to strengthen early next week with H5
heights rising to between 598-601dm over eastern portions of the
region by Tuesday or Wednesday. The likely strength of this ridge
puts it into record territory for the climatological period over
the entire region by next Wednesday and Thursday. Temperatures
should quickly respond by climbing to at least 112-116 degrees by
Wednesday and potentially a couple degree hotter for next
Thursday and Friday. There is still some uncertainty with how
much moisture will be around during the latter half of next week,
but in reality it seems unlikely to be enough to stop us from
seeing an Extreme Heat event.

An Extreme Heat Watch has been issued for south-central and
portions of eastern Arizona for Tuesday-Friday and across
southwest Arizona and southeast California for Wednesday-Friday.
Widespread Major HeatRisk with localized Extreme HeatRisk is
seen developing by next Wednesday, potentially lasting through
around next Friday. NBM deterministic forecast temperatures are
still coming in on the lower end of potential guidance, so there
is definitely room for forecast temperatures to go higher. In
fact, the NBM 75th percentile shows readings up to 120 degrees for
KPHX next Thursday and Friday. The hottest Phoenix has ever
recorded in the month of August was 117 degrees which has happened
4 times (2011, 2015, 2020, and 2023). Overnight lows are also
expected to climb back to around the 90 degree mark for the
Phoenix metro with a night or two later next week potentially in
the mid 90s.

&&

.AVIATION...Updated at 1705Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation weather concerns are expected through the TAF
period. Winds will follow familiar diurnal trends, with typical
afternoon/evening breeziness around 15-20 kts. The transition to a
W`rly component will slower than usual as winds will likely
fluctuate 150v220 between 18-21Z. Outside of a FEW distant CU
bases around 10 kft, skies will remain mostly clear.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns are expected through the next
24 hours under clear skies. Winds will continue to follow diurnal
trends, with afternoon gusts at KBLH around 20-25 kts. KIPL may
see some occasional gusts this evening in conjunction with the
W`rly shift.

&&

.FIRE WEATHER...
Drying conditions will occur today into the weekend with only a
limited chance for a few showers and isolated thunderstorms over
the eastern Arizona higher terrain through this evening.
Afternoon MinRHs today will still be between 10-15% across the
lower deserts to 15-20% in higher terrain areas before dropping
further into the weekend. Winds will generally follow diurnal
tendencies with typical afternoon upslope gustiness. Temperatures
will remain above normal with lower desert highs mostly between
108-114 degrees. Overall dry and hot conditions will continue to
prevail into next week with only very limited mostly high terrain
chances around Tuesday or Wednesday.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Watch from Wednesday morning through Friday evening
     for AZZ530>533-535-536.

     Extreme Heat Warning until 8 PM MST Saturday for AZZ534-537>544-
     546-548>555-559.

     Extreme Heat Watch from Tuesday morning through Friday evening
     for AZZ534-537>563.

CA...Extreme Heat Watch from Wednesday morning through Friday evening
     for CAZ560>570.

&&

$$

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