006
FXUS65 KPSR 051130
AFDPSR

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

.UPDATE...Updated 12Z 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.

&&

.DISCUSSION...
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 1130Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
Light diurnal wind tendencies and mostly clear skies will prevail
through today. Wind speeds will mostly remain <10 kts with
extended periods of light variability, especially this morning.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns through the TAF period with mostly clear
skies prevailing. Winds at KIPL will favor SE directions and S
directions at KBLH. Wind speeds at both terminals will remain
mostly aob 10 kts. There will be a surge of southerly winds this
evening, beginning around 00-02Z at both terminals, that will be
capable of pushing speeds to 10-15 kts with gusts into the upper
teens for a few hours.

&&

.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...Benedict/Ryan
FIRE WEATHER...Kuhlman