374
FXUS65 KPSR 150911
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
211 AM MST Sun Jun 15 2025

.KEY MESSAGES...

- Hot and dry weather is forecast throughout the entire upcoming
  week with the hottest days expected to be today and Thursday.

- An Extreme Heat Warning is currently in effect through Monday
  evening for high temperatures ranging from 109 to 115 degrees
  across the lower deserts.

- Widespread Moderate HeatRisk will be seen from Tuesday through
  Friday with high temperatures ranging from 107 to 113 degrees
  across the lower deserts.


&&

.DISCUSSION...
The main story for the upcoming week will be the persistent hot
and dry conditions as the sub-tropical ridge will remain the
dominant weather feature over the Southwestern U.S. The center of
the ridge is now over southwest New Mexico with H5 heights for our
area today ranging from 593dm over southeast California to 595dm
over far southeast Arizona. Today is also expected to be the
hottest day of the week with most lower desert locations topping
110 degrees to as high as 113-115 degrees for the typical hottest
locations. This will present areas of Major HeatRisk today with
some more localized areas carrying over into Monday as
temperatures drop a degree or two due to the ridge beginning to
get flattened out from an incoming shortwave trough.

The only thing that likely keep our area from having a few more
days of Major HeatRisk should be the incoming shortwave trough
which is shown to track through northern/central California early
Monday before brushing over northern portions of our region
Monday night/early Tuesday. Model guidance initially showed this
disturbance moving straight through our region, but now it will
likely just be a brush by and not result in much cooling. NBM
forecast temperatures do drop 2-3 degrees from Monday to Tuesday,
but some locations may still reach 110 degrees Tuesday. The ridge
will get flattened out briefly due to this passing disturbance,
but H5 heights may not even dip below 590dm across our area. The
ridge should then rebuild back over our region starting Wednesday
before peak H5 heights of 593-595dm are likely to be seen again on
Thursday. This rebuilding of the ridge will in turn push
temperatures higher again, likely to above 110 degrees for the
warmest lower desert areas to as high as 112-114 degrees on
Thursday. Though we technically expect to have a break in the
Extreme Heat conditions on Tuesday and maybe Wednesday, its
possible we may either have to extend the current Warning, or
reissue again for a day or two later this week. We should have a
better idea on how this will unfold over the next day or two.

By around Friday into next weekend, ensembles favor a larger
Pacific trough diving southeastward across the Pacific Northwest,
likely into at least the Great Basin area. For now, guidance
suggests this will eventually displace the sub-tropical ridge well
to our east late next weekend, likely giving us a reprieve from
the above normal temperatures. NBM forecast temperatures for next
weekend show highs dropping more into a 102-108 degree range due
to the passing trough, as well as partially due a slight uptick in
low level moisture. Models have been fairly consistent in showing
a gradual moisture increase (at least into eastern Arizona)
during the last week of June, but it barely looks to be enough to
bring higher terrain spotty convection.

&&

.AVIATION...Updated at 0530Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:

No aviation concerns are anticipated through the forecast period,
with wind speeds mostly remaining at or below 8 kts and following
typical diurnal directional trends. Periods of variability
between transition periods will be common. FEW high cirrus will
become SKC overnight.

Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation concerns are expected through the TAF period. Winds
at KIPL will favor a E/SE component through most of the period,
while KBLH will see a predominant S component. Wind speeds will
remain light aob 8 kts at KIPL through most of the period, while
KBLH will see 10 kt winds during the daytime hours, with lighter
winds during the overnight hours. Winds may shift out of the W`rly
direction tomorrow evening at IPL. FEW passing high cirrus during
the overnight hours will become SKC by tomorrow morning.

&&

.FIRE WEATHER...
Strong high pressure will continue to bring hot and seasonably
dry conditions, especially today, before a weak and dry
disturbance brushes across northern portions of the region Monday
night into Tuesday. High temperatures will peak today between 110
to 115 degrees across the lower deserts before dropping off to
between 106-111 degrees by Tuesday. Wind patterns will continue to
follow diurnal trends (upslope and downvalley) with afternoon
gusts up to around 20 mph today and around 25 mph focused more
over the eastern Arizona higher terrain on Monday. Humidities will
stay low with MinRHs between 5-10% and overnight MaxRHs only
between 20-30%. High pressure will remain the dominant weather
feature through the rest of the week with temperatures remaining
above normal through at least Friday and afternoon MinRHs likely
staying between 5-10% each day.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Monday for AZZ530>544-
     546>556-559>562.

CA...Extreme Heat Warning until 8 PM PDT Monday for CAZ562>567-569-
     570.

&&

$$

DISCUSSION...Kuhlman
AVIATION...Young/Smith
FIRE WEATHER...Kuhlman