313
FXUS65 KPSR 160518
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1018 PM MST Sun Jun 15 2025

.UPDATE...Updated 06z Aviation Discussion.

&&

.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 115 degrees
  across the lower deserts.

&&

.DISCUSSION...
Continued hot and dry weather conditions will be the main weather
story for the upcoming workweek as a strong subtropical ridge of
high pressure persists over the region. Latest afternoon objective
analysis shows the subtropical ridge centered over southwest New
Mexico with 500 mb heights across our area around 593-595 dm (90-
99th climatological percentile). The hottest temperatures so far
this year are expected this afternoon as a result, with highs
expected to top out around 111-115 degrees for most lower desert
locales. In Phoenix, temperatures will flirt with the daily record
high of 115 degrees last set in 2021. Given these temperatures,
widespread Major HeatRisk will cover much of the lower deserts and
into the southern Gila County high terrain today. For Monday,
forecast afternoon highs only drop 1-3 degrees with continued
areas of Major HeatRisk. An Extreme Heat Warning remains in effect
through Monday evening for most of the area.

Going into early Tuesday, a weak shortwave trough is set to move
through northern portions of the state and will briefly flatten
out the ridge and lower our heights during the first part of the
week. Ensemble guidance show 500 mb heights lowering to around 590
dm before rising again going into Wednesday following the passage
of the trough. The passage of this weak shortwave will result in
daytime highs Tuesday dropping 2-4 degrees compared to Monday.
This "cool down" won`t last for long as the subtropical ridge
builds back over the region with 500 mb heights rising to around
592-594 dm by Thursday. Temperatures will once again heat up for
the middle part of the week, with Thursday expected to be the
hottest day as highs push upwards of 110-115 degrees across the
lower deserts. Despite technically having a brief break in the
Extreme Heat conditions on Tuesday and perhaps Wednesday, we will
likely need to either extend the current Extreme Heat Warning
through the workweek or reissue again for a day or two later this
week. Widespread moderate HeatRisk is expected through much of the
workweek, however, temperatures are expected to flirt with Major
HeatRisk thresholds throughout the week.

.PREVIOUS DISCUSSION...
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 0520Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No aviation weather concerns will exist through the TAF period
under clear skies. Winds will follow typical diurnal patterns,
with speeds remaining generally AOB 12 kts through tomorrow
afternoon and periods of variability during transition periods. An
earlier than usual switch to west winds is expected by late Monday
morning, with gusts to 15-20 kts becoming common during the
afternoon hours tomorrow afternoon, with gustiness subsiding
during the evening hours.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns will exist through tomorrow afternoon
under clear skies. Winds will generally follow familiar patterns,
favoring S/SE this afternoon into the early evening before
shifting SW/W at both terminals. Speeds should remain mostly AOB
10 kts except during the late afternoon and early evening hours,
as a period of gusty SW/W winds 20-25 kts expected to develop at
both terminals before subsiding going into the overnight hours.

&&

.FIRE WEATHER...
Strong high pressure will continue to bring hot and seasonably
dry conditions before a weak and dry disturbance brushes across
northern portions of the region Monday night into Tuesday.
Temperatures will remain above normal with highs near or above 110
degrees each day across the lower deserts. Wind patterns will
continue to follow diurnal trends (upslope and downvalley) with
afternoon gusts up to around 20-25 mph the next couple of days,
particularly across the higher terrain east of Phoenix. Humidities
will stay low with MinRHs between 5-10% and overnight MaxRHs only
between 15-30%. Afternoon gusts combined with the dry conditions
may lead to some elevated fire weather conditions, especially
across the higher terrain east of Phoenix. 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...Smith
PREVIOUS DISCUSSION...Kuhlman
AVIATION...Young/Whittock
FIRE WEATHER...Smith/Kuhlman