667
FXUS65 KPSR 160510
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1010 PM MST Wed Oct 15 2025

.UPDATE...Updated Aviation Discussion

&&

.KEY MESSAGES...

- Dry and tranquil weather conditions with near zero rain chances
  will prevail through the weekend with temperatures remaining
  below normal.

&&

.SHORT TERM /Today through Thursday/...
Early afternoon water vapor satellite imagery shows a deep upper-
level trough over the Great Basin with dry southwesterly flow
continuing to erode the moisture content over the region.
Therefore, continued dry conditions with mostly clear skies will
prevail. Under the influence of the upper-level trough, afternoon
high temperatures will be well-below normal with readings only
topping out in the mid to upper 70s, which is a good 10-13
degrees below normal. On Thursday, the upper-level trough will
continue to migrate northeastward and be situated over the
northern Rockies, however, the continued negative height anomalies
will continue to keep temperatures well-below normal, albeit
slightly warmer than today, as afternoon highs top out in the
upper 70s to low 80s. Early morning low temperatures will also be
on the cooler side as many areas outside of the main urban
corridors will bottom out well in the 50s with some of the
sheltered, rural valley locations potentially getting down into
the upper 40s.

&&

.LONG TERM /Friday through Tuesday/...
Lingering positively tilted troughing associated with the exiting
system will continue to affect the forecast area late in the week
with a reinforcing shot of lower midlevel heights and dry NW flow
tempering any warming trend. However, all modeling suites are in
good agreement that shortwave ridging and H5 heights in excess of
588dm will temporarily build into the SW Conus over the weekend
allowing temperatures to finally rebound closer to the seasonal
normal. Early next week, ensemble membership continues to display
uncertainty regarding renewed Pacific troughing entering the
western Conus. One subset of models (including many GEFS members)
phase northern stream energy with lingering weaknesses in the height
field off the California coast into deepening progressive downstream
flow (a very La Nina-like pattern). However, another subset of
models (now flip-flopping from the operational GFS to ECMWF and many
CMC members) disconnect these features without any phasing resulting
in lower heights, cooler temperatures, and potentially some low
impact unsettled weather over the SW Conus. Recent NBM output seems
to favor the former solution reverting a cooling trend into a near
persistence forecast while advertising light winds and very low
POPs. Given the wide range among ensemble members, forecast
confidence during this time frame is somewhat lower than usual,
albeit with limited impacts regardless of the outcome.

&&

.AVIATION...Updated at 0510Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation concerns are expected during the TAF period. Winds
will follow light and diurnal trends with extended periods of VRB
to calm conditions. Confidence remains low regarding the typical E
shift at KPHX Thursday morning, but if one were to occur, it will
only be for a brief window and occur later than usual. Clear skies
will prevail through Thursday evening.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected over the next 24 hours. Winds
will generally contain a W`rly component with perhaps some brief
switches to the NNE at KBLH during the late morning and afternoon
hours. Also at KBLH, a few gusts in the mid-teens may be observed
during the late morning hours, but these have been excluded from
the TAF at this time as they will amount to very little
operational impacts. Clear skies will prevail through Thursday
evening.


&&

.FIRE WEATHER...
Dry, tranquil weather conditions will prevail through early next
week under a steady drying trend. Minimum humidity levels will only
fall into a 25-50% range today, then gradually deteriorate closer to
a 15-30% over the weekend. With the exception of some far western
district locations, overnight recovery will largely be good to
excellent above 50%. Winds will be far weaker the remainder of the
week with limited gustiness. Winds should be rather weak with
limited gustiness through early next week under a typical diurnal
upslope/nocturnal drainage pattern.

&&

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

$$

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