709
FXUS65 KPSR 172047
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
147 PM MST Tue Jun 17 2025

.KEY MESSAGES...

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

- Extreme Heat Warnings are in effect through much of the workweek
  across south-central Arizona for high temperatures ranging from
  108 to 116 degrees across the lower deserts.

- Widespread Moderate HeatRisk will be seen throughout the week
  before widespread Major HeatRisk prevails Thursday across south-
  central Arizona.

&&

.DISCUSSION...
Hot and dry weather conditions remain in place across the Desert
Southwest as the the subtropical ridge of high pressure remains the
dominant weather feature over the region. Early afternoon objective
analysis shows a weak shortwave trough now pushing through the
central Rockies and has led to a slight dip in 500 mb heights to
around 590 dm. As a result, afternoon highs today will be around 2-3
degrees cooler. Temperatures trend back up again starting tomorrow
as the subtropical ridge builds back over the region before peaking
on Thursday. Given this, Major HeatRisk will once again begin to
increase across the region, primarily across south-central Arizona.
Guidance show 500 mb heights continuing to rise going forward before
peaking around 594 dm Thursday. Thus, Thursday will be the hottest
day with widespread Major HeatRisk with the forecast high for
Phoenix coming within a couple degrees of the daily record high.
Extreme Heat Warnings are in effect for the Phoenix metro through
Friday before the warning expands to include most of south-central
Arizona tomorrow through Friday.

As the ridge reaches its peak intensity on Thursday, temperatures
will respond with the hottest temperatures of the week expected.
Forecast highs Thursday will climb upwards of 112-116 degrees
across south-central Arizona and 111-114 degrees across the
western deserts. After Thursday, temperatures will begin to trend
down as a potent Pacific trough begins to push into the Pacific
Northwest. This trough will act to displace the subtropical ridge
and lower heights over the southwest CONUS, resulting in lowering
temperatures and an end to our extreme heat conditions going into
this weekend. By Saturday, forecast highs drop below 110 degrees
and will return to near normal readings.

.PREVIOUS DISCUSSION...
Ensemble guidance shows the trough getting fully displaced to our
east Saturday night into Sunday, quickly lowering daytime highs
back to near or even a couple degrees below normal by Sunday. This
should quickly lower our HeatRisk across the region to either
Minor or at most low-end Moderate. This large trough is expected
to stall out over the Western U.S. for several days, likely
through at least the first part of next week. NBM temperature
guidance has shifted temperatures even lower for the first part of
next week with highs mainly between 100-104 degrees for Sunday-
Tuesday. Models are also showing some moisture seeping into
southern and central Arizona starting this weekend, but it is not
expected to be enough to bring any rain chances for any locations
except for far southeast Arizona. The bulk of the available
moisture is expected to go into New Mexico where much of the state
should see decent rain chances next week.

&&

.AVIATION...Updated at 1704Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major aviation concerns through the TAF period under clear
skies. Typical diurnal wind patterns with afternoon and early
evening gustiness 15-20 kts, out of the west, will continue to be
common through the period. By this evening gusts will relax and
remain aob 10kts for the overnight period.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns will exist through the TAF period under
clear skies. Winds at both terminals will continue to be light and
variable. At KIPL, winds will become SE`rly early this afternoon,
before going SW`rly this evening. At KBLH, W`rly winds will shift
around to the S by late this afternoon.

&&

.FIRE WEATHER...
Hot and dry conditions with modest afternoon breeziness will
continue over the next several days. 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, 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. By the
weekend, a dry weather system will eventually move into the region
from the west, dropping temperatures to around normal while also
increasing MinRHs into the teens. This should also increase winds,
most likely on Friday and Saturday, with afternoon gusts of 25-30
mph possible.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning until 8 PM MST Friday for AZZ537-540>544-
     546-548>551.

     Extreme Heat Warning from 10 AM Wednesday to 8 PM MST Friday for
     AZZ534-538-539-547-552>556-559>562.

CA...None.
&&

$$

DISCUSSION...Smith
PREVIOUS DISCUSSION...Kuhlman
AVIATION...Ryan/Berislavich
FIRE WEATHER...Kuhlman