671
FXUS65 KPSR 010758
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1258 AM MST Sat Aug 1 2026

.KEY MESSAGES...

- Extreme heat will persist through the start of next week with
  high temperatures topping out in the 110 to 118 degree range
  over much of the lower deserts, hovering right around record
  levels.

- Extreme Heat Warnings are in effect regionwide now through Monday.

- High pressure and drier air over the region will confine
  showers and thunderstorms primarily to far eastern and
  southeastern Arizona areas through at least Monday.

- Shower and thunderstorm chances increase across south-central
  Arizona by the second half of next week.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...
The 00Z sounding out of Flagstaff sampled an H5 height of 601dam,
which ties for second highest based on the SPC Sounding
Climatology page for Flagstaff. The sounding also measured an H5
temperature of -4.5C, which is above the 90th percentile, and
mesoanalysis shows even warmer 500mb temperatures toward the
central CA-NV border. Suffice to say, the atmosphere is very hot
right now and extreme heat will continue to be the primary weather
hazard through this weekend as high pressure remains centered
over the area and H5 heights hold near 598-600dam. High and low
temperatures will be near or tying/breaking daily records across
the region through Monday. High temperatures today and Sunday will
be very similar, with the lower deserts peaking near 114-119
degrees. Then, as the high starts to weaken slightly into the
start of next workweek, high temperatures will come down 1-3
degrees for Monday. Morning lows in the 80s to lower 90s will
offer minimal relief from the heat and the combination of these
high and low temperatures will lead to widespread Major HeatRisk
and many areas of Extreme HeatRisk, including across all of
Phoenix. Extreme HeatRisk means the entire population is at risk
for significant heat health impacts. An Extreme Heat Warning
remains in effect today through the start of the workweek.

With the very warm air aloft, subsidence, and near to below
normal moisture levels, it is no surprise that this strong high
pressure is inhibiting monsoon thunderstorms across much of the
region. The next few afternoons and evenings storms will continue
to favor primarily the White Mountains and across Southeast AZ,
and a northeasterly steering flow will keep these storms
progressing to the southwest. Isolated storms may start clipping
into far southeastern Gila County beginning as early as Sunday,
with the main impact being strong gusty outflow winds. Distant
outflows may also begin reaching into portions of south-central AZ
starting Sunday, but the winds with them are not likely to be
very strong initially, given the northeasterly steering flow, and
no additional convection is expected to be generated by these
outflows given the poor environment in south-central AZ. Despite
this, a few high-based showers cannot be fully ruled out during
the early morning hours, even this morning just to the east and
southeast of Phoenix as some hi-res models have suggested.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
The monsoon high is forecast to weaken Sunday into Monday with H5
heights dropping to 594-596dam, or right around the 90th
percentile of climatology, by the end of the day Monday. The high
will also become flatter and more stretched out across the
southern tier of the CONUS and likely persist through the end of
the week. Despite the high weakening, the residual heat dome will
take some time to cool. High temperatures are forecast to cool 1-3
degrees into Tuesday, from Monday`s readings, and another 1-3
degrees into Wednesday. Lows will remain quite warm each day,
mainly in the mid 80s to around 90F across the lower deserts. The
extreme heat footprint will decrease as the temperatures decline,
but a continuation of the Extreme Heat Warning through Tuesday may
be needed for at least the Phoenix area with lingering widespread
Major HeatRisk across the metro area based on the current
forecast. Most other areas will fall to the Moderate risk level
by Tuesday. Temperatures are then forecast to remain fairly
similar day-to-day Wednesday through the end of the week, with
minimal synoptic changes, barring any storm influences.

With the weaker and flatter high, and being on the southern half
of the high, there will be a longer fetch of easterly winds across
southern New Mexico, southern Arizona, and northern Mexico by
Tuesday. This pattern shift will allow moisture to begin to
increase again across southern and eastern Arizona Monday through
the middle of the week. As a result, convective potential will
tick upwards early next week, and the easterly steering flow
across southern Arizona will be a better trajectory across the
area to help spread convection more into the lower deserts by the
second half of next week. Latest NBM/WPC forecast show 10-30% PoPs
across south-central Arizona by Wednesday and continuing through
the end of the week. Despite lower PoPs on Tuesday, strong outflow
winds may at least progress through south-central Arizona. The
synoptic pattern next week will open the door for some easterly
waves/inverted troughs to progress across the area and enhance
convective potential, but it is still too early for models to
fully resolve any of these features to help determine what day, if
any, will have better odds for storms across the lower deserts.

&&

.AVIATION...Updated at 0445Z.

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 can be
expected early Saturday morning. Some occasional gusts in the mid
to upper teens are likely Saturday afternoon/early evening. There
may be a period of virga showers early Saturday morning, mainly
to the east of the terminals.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns under some passing high cirrus
cloud decks can be expected throughout the TAF period. At KIPL,
winds will generally be out of the southeast with the exception
early Saturday evening, when a temporary shift out of the west is
likely. At KBLH, winds will vary between the south-southeast to
southwest with periods of variable conditions likely early
Saturday morning. Overall wind speeds will generally remain aob 10
kts, with some occasional afternoon gusts into the mid to upper
teens at KBLH.

&&

.FIRE WEATHER...
Strong high pressure and very hot temperatures, with dry
conditions, will persist through this weekend. Afternoon high
temperatures will be up to 112-118 degrees across lower elevations
and minimum RH values will be around 10-15%. Temperatures then
decline a few degrees each day through the first half of the week
and moisture levels will slowly rise. Minimum RHs will still be
around 15-20% Monday, but will increase up to 20-30% starting
Tuesday. Overnight RH recoveries will be fair to good this weekend
at 30-45% and then increase up to 45-70%. The increasing moisture
will result in an increase in shower and storm chances. Initially,
storm chances this weekend through the start of the week will
focus in far eastern and southeastern AZ, with potential for storm
outflow winds to progress into south-central AZ. Slight chances
for storms (15-30%) then spread to south-central AZ by the middle
and second half of the week. Outside of storm outflows, 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
----       -------         ----         ---------
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...Benedict
LONG TERM...Benedict/Kuhlman
AVIATION...Lojero
FIRE WEATHER...Benedict
CLIMATE...18

NWS Phoenix (PSR) Office