119
FXUS65 KPSR 201729
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1029 AM MST Sun Sep 20 2026

.UPDATE...Updated Aviation Discussion.

&&

.KEY MESSAGES...

- Dry, tranquil weather conditions with near to slightly above normal
  temperatures will continue through the first half of next week.


- A low pressure system with returning moisture will yield renewed
  rainfall chances to at least the high terrain of northern and
  eastern Arizona during the latter half of next week.

&&

.SHORT TERM /Today through Monday/...
Water vapor satellite imagery early this morning shows a low
pressure system centered over Wyoming and a high pressure system
centered over eastern Texas. The aforementioned low has moved
further north and east than this time yesterday, which has
resulted in westerly flow aloft over the Desert Southwest instead
of the southwesterly flow that was overhead yesterday.
Additionally, water vapor satellite imagery depicts another low
pressure system well off the coast of central California. This low
will slowly approach the coast today and eventually move onshore
tomorrow. There will be some small increases in moisture over the
next couple of days (gong from less than 0.7" today to around
0.6-1.0" over the next couple of days) , but the dry
west/southwesterly flow aloft will dominate the region and hinder
any shower or storm chances through the beginning of the workweek.
H5 heights will remain around 585-588dm across our region which
gives excellent confidence that temperatures will remain steady
state through tomorrow. Temperatures will continue o be a few
degrees above normal resulting in minor HeatRisk.

&&

.LONG TERM /Tuesday through Saturday/...
On Tuesday, the Pacific low will slowly weaken as it moves
northeast into NV/UT before moving into the northern Plains on
Wednesday. At the same time, a weak ridge over SE TX will
strengthen slightly resulting in a return of southwesterly flow
over the Desert Southwest. This will result in a gradual return of
moisture across southern Arizona. This increase in moisture and
some upper level forcing from the aforementioned low, slight
chances for showers and storms will return to the higher terrain
areas in northern and eastern Arizona. After this low advects into
the northern Plains by the middle of the week, weak large scale
troughing will remain across the eastern Pacific/West Coast
through the end of the week. By the end of the week, the high
pressure system over TX will try to retrograde over NM/AZ, but it
will be battling the large scale troughing over the West.
Ensembles show PWATs staying around 1.0-1.3" across southern AZ
through the end of the week. As a result, NBM/WPC PoPs for the end
of the week continue to show 30-50% across the higher terrain of
southern Gila County and 10-20% across the south- central AZ lower
deserts.

Temperatures this coming week will remain largely unchanged, but are
expected to dip a couple degrees midweek as the low pressure system
moves to the north of our area and cause H5 heights to dip to around
582-585 dm. Regardless, afternoon highs will generally be in the
upper 90s to low 100s across the lower deserts, and in the upper 80s
to mid 90s across the higher terrain. Morning lows will generally be
in the 70s to to low 80s across the lower deserts, and in the 60s
across the higher terrain areas. Morning lows should start to creep
up by the end of the upcoming workweek (more morning lows in the low
80s across the lower deserts). As a result, widespread minor
HeatRisk will continue through the first half of the week with
moderate HeatRisk returning to the lower deserts for the latter half
of next week as the morning lows creep up and daily normals
decrease.

&&

.AVIATION...Updated at 1730Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation concerns are expected during the TAF period
under increasing mid and high cloud decks. Winds will generally
follow diurnal trends through Monday morning, with speeds AOB 10
kts and periods of variability likely. By Monday late morning, a
more prolonged period with a southerly cross-runway wind component
(for KPHX, KDVT) is anticipated to develop and may prevent the
typical SW/W switch Monday afternoon. Cloud bases will remain
above 8K ft AGL through the period.

Southeast California/Southwest Arizona including KIPL and KBLH:
The only weather issue during the next 24 hours will be low
confidence on wind directions, especially at KIPL, under BKN high
cloud decks. Winds will generally favor SE/S at both terminals
with speeds below 10 kts, however, directions may veer out of the
SW for a period this evening. Confidence is moderate to good on a
period of VRB winds developing overnight into Monday morning at
both terminals.


&&

.FIRE WEATHER...
Temperatures will remain fairly steady through the upcoming week
and be around 2-5 degrees above normal. Dry conditions with no
chances for showers or storms continue through tomorrow. Daily,
low-end, chances for showers and storms return to the higher
terrain areas of southern Gila County beginning on Tuesday. MinRHs
will be around 10-25% today before increasing to around 15-30%
across the central and western districts and 30-50% across the
eastern districts for next week. Overnight recoveries will range
from fair to good across the central and western districts and
good to excellent across the eastern districts through next week.
Besides a slight increase in breeziness early this upcoming
workweek as a weather system moves through the region, winds will
mostly follow typical diurnal patterns with modest afternoon
upslope/upvalley gustiness (15-25 mph).

&&

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

$$

SHORT TERM...Berislavich
LONG TERM...Berislavich
AVIATION...Whittock
FIRE WEATHER...Berislavich