194
FXUS65 KPSR 050921
AFDPSR
Area Forecast Discussion
National Weather Service Phoenix AZ
221 AM MST Fri Sep 5 2025
.KEY MESSAGES...
- Chances for showers and isolated thunderstorms will remain
through Saturday before rain chances end completely starting
Sunday.
- Temperatures will be below normal through Sunday before warming
back into the normal range for at least south-central and
eastern Arizona through the middle of next week.
&&
.SHORT TERM /Today through Saturday/...
Today into Saturday will bring a diminishing threat of storms as
drier air aloft begins to spread over the region and increased
subsidence likely limits areal coverage. For the rest of the
overnight hours, we may see a few isolated showers but most
locations will see clearing skies and somewhat humid conditions.
The trough axis that aided in storm development the last couple of
days has now moved to the east of the area with weak ridging
moving in from the west. Moisture in the low and mid levels will
remain quite high today, but above 600mb northerly dry air will
act to limit storm activity today. Hi-res CAMs mostly shows
isolated showers and weak storms across the Arizona high terrain
and maybe an isolated shower or two over the lower deserts. We
can`t rule out some isolated shower activity during the overnight
hours tonight, but there is no model consensus for exactly where.
PoPs through tonight have been lowered to between 10-20%.
Going into the weekend, the large Pacific trough off the West
Coast will begin to influence our region more bringing westerly
dry flow across the entire Desert Southwest. The drier air aloft
will persist and get even drier, gradually mixing out whats left
of the mid level moisture this weekend. Moisture levels on
Saturday are likely to still be enough for some isolated showers
and maybe a few weak storms, but as with today the favored areas
for this activity will be over the Arizona high terrain.
Temperatures over the next couple of days will barely budge with
daytime highs from the mid 90s across the south-central Arizona
lower deserts to the upper 90s across the western deserts, or
around five degrees below normals.
&&
.LONG TERM /Sunday through Thursday/...
Overall quiet and drying conditions are forecast for Sunday
through at least the middle of next week. The Pacific trough is
expected to deepen and fully close off west of Northwest U.S.
coast this weekend before moving onshore on Monday. As it deepens
starting Sunday, it should promote amplified upper level ridging
centered along the Arizona/New Mexico border northward into
Wyoming. This is expected to briefly boost H5 heights over much
of our region into a 590-593dm range leading to warmer
temperatures for at least Sunday and Monday. NBM forecast highs
show readings right around 100 degrees for Sunday across the lower
deserts to between 101-104 degrees on Monday and Tuesday. Further
drying through early next week should completely end rain chances
even across the higher terrain by Monday and eventually lower
surface dew points into the 40s by next Tuesday or Wednesday.
Model uncertainty increases somewhat during the middle to latter
part of next week as there are differences within the models with
the eventual evolution of the Pacific trough. There is at least
good agreement with H5 heights lowering over our region by next
Wednesday as the trough moves fully over the Western U.S., but
there are bigger differences late next week with how far south
and east the base of the trough will track. For now, we can safely
say this pattern should keep considerable dry air over most if
not all of our region through late next week. Forecast
temperatures show higher spread later next week, but the overall
consensus shows a slight cooling trend and readings staying at or
just below normals during the latter half of next week.
&&
.AVIATION...Updated at 0530Z.
South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation weather concerns are expected throughout the TAF
period. The overall wind pattern will follow the typical diurnal
tendencies with speeds aob 10 kts with periods of light
variability. No thunderstorms or outflow boundaries are expected
for Friday. FEW-SCT mid to high clouds will persist throughout the
period.
Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns are expected throughout the
TAF period. Winds at KIPL will generally be out of the southeast
and out of the south at KBLH with speeds generally aob 10 kts.
FEW-SCT mid to high clouds will persist throughout the period.
&&
.FIRE WEATHER...
Higher low level moisture will continue into the weekend, but
rain chances will be diminishing and ending altogether by Sunday.
Expect periods of isolated showers and weak storms through
Saturday, but wetting rain chances will mostly range between
10-20%. MinRHs are only expected to drop into a 30-45% range
through the weekend as temperatures stay below normal. Winds will
tend to favor diurnal patterns across the eastern districts,
while favoring the south across the western districts. The
gradual drying conditions will continue during the first half of
next week keeping rain chances near zero and eventually lowering
MinRHs back into the teens by next Tuesday.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
SHORT TERM...Kuhlman
LONG TERM...Kuhlman
AVIATION...Lojero
FIRE WEATHER...Kuhlman
NWS Phoenix Office
Tucson, AZ 
