265
FXUS65 KPSR 201733
AFDPSR
Area Forecast Discussion
National Weather Service Phoenix AZ
1033 AM MST Mon Oct 20 2025
.UPDATE...Updated 18Z Aviation Discussion.
&&
.KEY MESSAGES...
- Tranquil weather conditions will persist throughout this week
with temperatures within a few degrees of the seasonal normal.
- A weather system passing north of Arizona during the middle of
the week may bring a few light showers over the Arizona high
terrain.
&&
.SHORT TERM /TODAY THROUGH TUESDAY/...
Current satellite shows clear skies across the area with upper
level ridging still stretched southeast to northwest across the
Southwestern U.S. A stationary cut-off low remains situated
roughly 600 miles southwest of San Diego with water vapor imagery
showing very little moisture associated with the system. H5
heights increased over the weekend reaching to 588dm over much of
southern California and the southern half of Arizona. For today,
expect nearly identical temperatures as we saw yesterday with
lower desert highs between 86-91 degrees. Guidance remains in good
agreement the cut-off low will eventually begin to track toward
southern California on Tuesday, but weather conditions over our
region Tuesday will be similar to today`s conditions. The only
changes for Tuesday may be an added degree or two onto the daytime
highs across the Phoenix area and the return of some thin higher
level clouds.
&&
.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
The cut-off low is still forecast to move through south-central
California on Wednesday as it starts to weaken. The track of the
low center may eventually move across northwest or most of
northern Arizona Wednesday night into Thursday, but with little
system moisture the vort center itself will have no impact on our
area. However, guidance is still showing some modest higher level
moisture advecting into Arizona Tuesday night into Wednesday with
the highest PWATs of around 0.8" centered over south-central
Arizona. This moisture may help to spark off some high-based light
showers by Wednesday morning, but only light accumulations are
expected and they will be confined to higher terrain areas north
and northeast of Phoenix. The lower deserts may see some virga
showers and some isolated sprinkles, but measurable rainfall is
very unlikely. Once the low center moves into northern Arizona
later on Wednesday, drier air will quickly spread west to east
across southern and central Arizona. Upper level ridging will
eventually move overhead by Friday and last through Saturday
before more zonal flow is likely to affect our region Sunday into
early next week. Dry conditions are expected to last through at
least next weekend will only periods of higher level clouds from
an AR affecting the northern half of California.
Temperatures for the latter half of the week into next week are
not expected to vary all that much. Thursday is still likely to be
the coolest day with highs in the lower 80s across south-central
Arizona to the mid 80s over the western deserts. Once the ridge
builds back in on Friday, highs should move more into the 85-90
degree range and stay there at least through Saturday before
returning into a normal range by early next week.
&&
.AVIATION...Updated at 1731Z.
South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:
No weather concerns are expected through the TAF period. Winds
will exhibit diurnal tendencies with periods of variability,
especially at KDVT and KSDL. Mostly clear skies with a FEW mid to
high clouds creeping into the region near the end of the TAF
period.
&&
.FIRE WEATHER...
High pressure will remain across the region through at least
Tuesday with slightly above normal temperatures. Humidities will
remain fairly stable with MinRHs mostly between 15-20% across the
lower deserts to 20-25% for higher terrain areas. Light winds are
also anticipated through at least Tuesday with directions mostly
following common diurnal patterns. A mostly dry weather system is
then expected to pass through the region on Wednesday bringing
slight chances for higher terrain light showers. The system
should also boost humidities slightly while also leading to a
period of occasional breezy westerly conditions focused on
Wednesday.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
SHORT TERM...Kuhlman
LONG TERM...Kuhlman
AVIATION...Ryan
FIRE WEATHER...Kuhlman
NWS Phoenix Office
Tucson, AZ 
