479
FXUS65 KPSR 120542
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1042 PM MST Tue Aug 11 2026

.UPDATE...Updated 06Z Aviation Discussion.

&&

.KEY MESSAGES...

- Better moisture and more favorable conditions for monsoon storm
  development is expected through midweek with the most
  widespread activity across south-central and eastern Arizona.

- Locally heavy rainfall and gusty thunderstorm winds will remain
  possible through Thursday before drying conditions ends rain
  chances as early as Friday.

- Cooling temperatures are expected through midweek, briefly
  falling to below normal Wednesday through Friday.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
GOES mid-level WV imagery and RAP40 500MB analysis continue to
show the upper level pattern with southeasterly flow aloft and the
core of the high pressure over the Four Corners region. By
Wednesday the high will be pushed eastwards towards Texas while a
trough deepens across the western coast, and is expected to remain
in place through the end of the week, bringing southwesterly flow
aloft. This will help gradually dry the region out especially
towards the later half of the week and heading into the weekend.
Otherwise for the rest of today, a mostly overturned atmosphere
from the past active nights will likely to limit shower and
thunderstorm activity compared to the last couple of days. HREF
shows a 30-50% chance of storm development in the eastern high
terrain with only a 10-20% chance of activity developing tonight
and into the overnight period for the lower deserts. That being
said the main impact/concern for the lower deserts will be breezy
to windy conditions from outflows, thats if they can survive into
the lower deserts.

Uncertainty remains high for Wednesday as the weak trough begins
to enter western portions of the region turning the flow out of
the south southwest. The incoming trough is expected to increase
upper level forcing across much of the area for Wednesday into
early Thursday, but as the flow shifts out of the south southwest
some dry air will begin to filter into western and then south-
central Arizona. However, plenty of moisture will remain from
around Phoenix and areas to the east and northeast of Phoenix. The
biggest question will be the areas of focus for shower and storms
from Wednesday afternoon through Thursday morning. Guidance
indicates the best chances from northern and eastern portions of
Phoenix into the higher terrain with PoPs of 50-70% with
decreasing chances to the south and west as that drier air enters
the region. A faster than normal storm movement should help to
limit the heavy rainfall threat, but the aforementioned factors
could still lead to some instances of flash flooding, especially
in NE AZ. The activity is likely to persist during the overnight
hours/Thursday morning, but the threat for heavy rainfall is
likely to gradually decrease.

The good news, outside of precipitation potential, will be that
this activity will lead to ample cloud coverage over the next few
days, helping temperatures to be near normal today, then 3F-6F
degrees below normal starting Wednesday. This will lead to a large
majority of the region dropping to Minor HeatRisk with the
exception of a small corner of SE CA, where localized areas of
Moderate will remain. Additionally the morning low temperatures
will continue to be near to slightly below normal through out the
rest of the work week.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
Drying is expected to pick up across the area during the latter
half of Thursday with most of the shower and thunderstorm
potential shifting to over the Arizona high terrain. By Friday,
enough dry air is expected to filter into the area to completely
end rain chances across the lower deserts while limited chances
are forecast for the high terrain. The subtropical high is
expected to stay centered across the Southeastern U.S. through at
least the weekend with broad troughing over much of the Western
U.S. This will keep dry air in place through at least the upcoming
weekend with at most slight chances for afternoon convection over
the far eastern Arizona high terrain. Ensembles do show the
subtropical high becoming more elongated late this weekend with
heights gradually increasing over our region. As a result,
temperatures are likely to climb back to around or even a few
degrees above normal by Sunday or Monday. The next potential for
rain could come as early as next Monday or Tuesday, but
uncertainty is quite high at a week away.

&&

.AVIATION...Updated at 0541Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Main forecast challenge over the next 24 hours will be timing out
VCSH/VCTS at terminals. Best potential looks to be Wednesday
afternoon and evening, but there is also potential for an outflow
to arrive from the south Wednesday morning and help spark spotty
high-based showers and an isolated storm. Prevailing west winds
will continue through midnight tonight at most terminals and then
will trend toward E/SE early Wednesday morning. An early W/SW wind
shift is expected Wednesday, by around 16-17Z, with speeds
increasing in the afternoon up to 7-12 kts with gusts up to 20
kts. FEW to SCT mid and high clouds will be common through the TAF
period with lowest bases down to 8K ft AGL Wednesday afternoon and
evening.

Southeast California/Southwest Arizona including KIPL and KBLH:
There will be a slight chance (10-20%) for VCSH/VCTS at both
terminals Wednesday, mainly between 22-01Z at KIPL and 23-04Z at
KBLH. Otherwise, a typical SW-SE wind component will prevail
through the TAF period. Wind speeds up to 7-12 kts will be common
at both terminals with gusts up to 20-25 kts at KBLH Wednesday
afternoon. FEW to SCT clouds will be common over the area with
lowest bases down to around 10K ft AGL.

&&

.FIRE WEATHER...
Scattered showers and thunderstorms are anticipated each day
through midweek across the higher terrain areas of the eastern
districts, with slightly lower chances in the lower elevations.
The best chances will fall during the latter half of Wednesday
into Thursday morning. Afternoon MinRHs will range between 25-35%
in the lower deserts and between 40-50% in the eastern high
terrain through Wednesday with good to excellent overnight
recoveries. Aside from gusty and erratic winds near thunderstorms,
the overall wind pattern will follow the diurnal trends with
modest afternoon upslope gusts. Near to below normal temperatures
are expected through the rest of the week with drying conditions
by Friday and lasting through next weekend.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

SHORT TERM...Ryan/Kuhlman
LONG TERM...Kuhlman
AVIATION...Benedict
FIRE WEATHER...Kuhlman