581
FXUS65 KPSR 152330
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
430 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 2330Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation weather concerns are expected during the forecast
period. Light and diurnal winds will prevail through Thursday
evening with windows of variability to even calm conditions during
the overnight/early morning hours. Confidence regarding the
occurrence of the usual E shift at KPHX is low, but if one were to
occur, it would be relatively brief. FEW low cloud decks this
evening will eventually give way to clear skies after sunset.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns are expected during the next 24
hours. W to NW winds will be favored at both terminals with
perhaps some brief winds of NNE`rly winds at KBLH late tomorrow
morning/early afternoon. 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