640
FXUS65 KPSR 051706
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1005 AM MST Thu Jun 5 2025

.UPDATE...
Updated Aviation

&&

.DISCUSSION...

KEY MESSAGES:

- Hot and dry conditions are expected into next week with lower
desert temperatures peaking near 110 degrees on Sunday and Monday

- Areas of Moderate HeatRisk develop by Saturday, likely persisting
through the middle part of next week

Drier air continues to spread into Arizona and far southern
California, despite weak troughing centered over central California
into the Great Basin. Moisture levels have dropped considerably
across south-central Arizona with PWATs now below 1" and surface dew
points around 50 degrees. The western deserts are still holding onto
some moisture with PWATs between 1-1.2" and a bit higher dew points,
but with the lack of any good forcing today the area should stay
mostly quiet. Locations into San Bernardino Co. may see some
isolated showers or thunderstorms this afternoon, but hi-res CAMs
show no activity into Riverside or Imperial Counties.

Today will also mark the start of the sub-tropical ridge nudging
into our region, which is currently centered over northern Mexico
and southern Texas. This ridge will however not fully make its way
into our region as the large scale troughing to our north and
northwest somewhat keeps it at bay. As the ridge partially moves
into our region over the next few days, H5 heights are seen rising
from around 582dm today to around 588dm by Sunday. This will
gradually push temperatures upward over the next several days with
highs around normal today and Friday before peaking Sunday and
Monday between 105-109 degrees across the south-central Arizona
lower deserts and 106-111 degrees across the western deserts. The
peak temperatures should end up around 4-8 degrees above normal, but
still at least 5 degrees shy of daily records.

The hot temperatures will push most locations into the Moderate
HeatRisk category starting Saturday. This weather pattern of the sub-
tropical ridge just to our south and a quai-zonal flow regime across
the northern tier states should persist through at least the middle
part of next week. Ensemble guidance does show our H5 heights
lowering a bit into the middle part of the week before a larger
trough eventually take shape off the Northwest U.S. late next week.
This should knock a few degrees off our temperatures during the
middle part of next week and possibly few more by next weekend as
temperatures are likely to retreat back to near normal. Dry
conditions and near consistently clear skies are expected for all of
next week under this pattern.

&&

.AVIATION...Updated at 1705Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major weather issues should exist through Friday afternoon under
a FEW midlevel cloud decks through this afternoon. The typical
afternoon wind shift may incorporate several hours of variable
directions with speeds under 8kt before settling on W/SW mid
afternoon through overnight. Confidence is moderate that the
overnight shift to easterly will be later this usual, and revision
back to west slightly earlier Friday.


Southeast California/Southwest Arizona including KIPL and KBLH:
No significant weather concerns will exist through Friday afternoon
under clear skies. S/SE wind directions will be favored through the
period with some variability and brief SW directional shifts
possible. Confidence is good that speeds will primarily remain below
10kt, however could increase closer to 15kt at times.

&&

.FIRE WEATHER...
Drying conditions and hotter temperatures are expected into the
weekend. Afternoon MinRHs will decrease from 15-20% today to 7-12%
by Saturday as lower desert high temperatures increase into the
lower triple digits, which is near normal range for this time of
year. Overnight RHs will also decrease from 30-45% tonight to 25-35%
Friday night. Winds should follow fairly typical diurnal tendencies
with periodic afternoon upslope gustiness. The dry weather pattern
is expected to continue into early next week with temperatures
running 5-10 degrees above normal and daily MinRHs mostly in a 5-10%
range.

&&

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

&&

$$

DISCUSSION...Kuhlman
AVIATION...18
FIRE WEATHER...Kuhlman