131
FXUS65 KPSR 032345
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
445 PM MST Thu Sep 3 2026

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- A few showers and storms are possible across south-central Arizona
late this afternoon into early this evening.

- Some tropical moisture arriving into the region through early
Friday will increase rain chances across the foothills and higher
terrain areas east of Phoenix before chances shift westward into
southwest Arizona and southeast California this weekend.

- Temperatures will remain in a near to slightly below normal
category through this weekend, resulting in widespread minor Heat
Risk and localized areas of moderate HeatRisk.

&&

.SHORT TERM /TODAY THROUGH FRIDAY/...
Latest objective analysis reveals a broad subtropical ridge
extending from the southern Plains into the southeastern U.S. while
a broad trough is encompassing the Pacific Northwest. This overall
pattern configuration is resulting in southwesterly flow across the
region, especially in the mid to upper-levels, which has advected
considerably drier air aloft. Meanwhile, moisture advection from
Hurricane Marie, located southwest of the tip of the Baja Peninsula
will result in a surge of low-level moisture heading into this
afternoon and tonight with PWATs likely to exceed 1.5 inches across
much of south-central and southeast AZ while much drier air with
PWATs of less than one inch is expected to be confined across
southwest AZ and southeast CA. The latest Hi-Res guidance for later
this afternoon and this evening does show some isolated showers and
storms popping up near some of the terrain features such as the
Table Top and Estrella Mountains in south-central AZ, however, the
very dry air above 600 mb will likely limit the residence time of
any activity. Some gusty winds and locally heavy rainfall will be
the main threats with any of these storms. Heading into tonight and
early Friday morning, guidance is showing another round of showers
and storms to develop across portions of southeast AZ and move
northward, affecting the foothills and higher terrain areas east of
Phoenix where the best moisture axis is likely to set up. With the
activity overnight into early Friday morning, some locally heavy
rainfall that could lead to localized flooding will be the main
threat. Quieter conditions are anticipated starting late Friday
morning as drier air filtering in from the west moves in, dropping
PWATs under 1.3" with little to no instability and thus eliminating
any rain/storm chances through the rest of the day.

Due to the presence of the troughing across the Pacific Northwest,
afternoon high temperatures this afternoon and Friday will be within
a few degrees of the daily normals as readings top out in the upper
90s to low 100s across much of the lower desert communities. The
associated height falls from the trough will also cause some
afternoon/early evening breeziness across portions of southeast CA
and southwest AZ with peak gusts upwards of 20-30 mph, potentially
upwards of 40 mph in the typical wind prone areas of far southwest
Imperial County.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Global models are coming into somewhat better agreement with the
pattern evolution this weekend. Both the ECMWF and GFS show high
pressure strengthening over the southern Plains with the western
periphery of the ridge extending over E AZ and NM. This will cause
the subtropical jet to shift wwd beginning Saturday, setting up
better moisture advection over southeast CA and southwest AZ. NBM
PoPs are still not overly impressive, mainly in the 20-30% range on
Saturday, however the GEFS/GFS indicates a final slug of moisture
from Marie being pulled into southeast CA on Sunday with PWATs
rising above 2.0". Therefore we will have to monitor for heavier
rainfall potential in portions of SE California including Joshua
Tree NP on Sunday. Elsewhere, across southcentral AZ, rain chances
look to be meager due to more extensive cloud cover and very low
instability. The latest WPC QPF field shows a local minimum in
rainfall totals (<0.10") in southcentral AZ including the Phoenix
Metro through this weekend. By early next week, there are large
discrepancies in the ridge/trough positioning which will complicate
the precipitation forecast, but there will still be adequate
moisture across our region which will keep low end PoPs in place
across eastern and southeastern AZ Monday and Tuesday with
potentially better precipitation chances arriving Wednesday.

The temperature forecast this weekend into early next week remains
largely unchanged, although there will likely be a gradual increase
from near normal temperatures on Saturday to slightly above normal
temperatures Sunday into early next week as ridging strengthens over
the region. Depending on how strong the ridge gets, NBM temps could
climb a few more degrees in subsequent runs and it is not out of the
question that we could see lower desert highs approaching 110
degrees as indicated by the NBM 75th percentile on Monday and
Tuesday.

&&

.AVIATION...Updated at 2345Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
The threat for isold TSRA this evening, then scattered SHRA early
Friday morning are both weather concerns along with uncertainty in
winds through Friday. Under periods of mid/high clouds decks, have
maintained a prob30 mention of TS this evening as activity may pop
over the Estrellas, however confidence is somewhat better that
scattered SHRA impact the area late tonight and near sunrise Friday
though even this activity may remain east of terminals. Otherwise,
winds may be highly variable through the period only briefly
obtaining a SW component this evening before reverting to E/SE.
SHRA may create erratic directions at times, and gusty 150v230 winds
may prevail early Friday afternoon before slowly becoming SW.


Southeast California/Southwest Arizona including KIPL and KBLH:
Occasional late afternoon/early evening gusty winds will be the main
weather issue through Friday evening under clear skies. SW gusts 20-
25kt will be common at KBLH late afternoon while KIPL should
experience the most pronounced gusts through the evening. Speeds
will relax overnight and early morning where periods of nearly calm
conditions will exist.

&&

.FIRE WEATHER...
Isolated to widely scattered showers and storms will be possible in
southcentral AZ later today through Friday. Rain chances will expand
westward through this weekend, becoming focused over the western
districts Saturday and Sunday. The best chances for wetting rainfall
will be over the higher terrain areas of eastern and southeastern
AZ. Afternoon minimum humidities will range from 7-15% across
southeast CA and between 20-35% for the remainder of the region
through Friday and will likely increase above 25% areawide this
weekend. Overnight recoveries will range from poor across the
western deserts and good to excellent across the eastern districts.
Daytime winds will remain elevated out of the south to southwest,
with the strongest gusts in Southeast CA and along the Lower
Colorado River Valley peaking between 20-30 mph during the
afternoon/early evening.

&&

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

&&

$$

SHORT TERM...Lojero
LONG TERM...Salerno
AVIATION...18
FIRE WEATHER...Whittock/Salerno