074
FXUS65 KPSR 162327
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
427 PM MST Mon Jun 16 2025

.UPDATE...Updated 00z Aviation Discussion.

&&

.KEY MESSAGES...

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

- Extreme Heat Warnings have been issued or extended through much
  of the workweek across south-central Arizona for high
  temperatures ranging from 108 to 116 degrees across the south-
  central Arizona 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 with extreme heat conditions continue as the
subtropical ridge of high pressure remains the dominant weather
feature over the region. Latest look at objective analysis this
afternoon shows the center of the high near the AZ/NM/MX border,
keeping heights over our area around 592-594 dm. With the ridge
persisting over the region, temperatures remain above normal with
afternoon temperatures so far today reaching or exceeding 110
degrees in many areas across the lower deserts. Areas of Major
HeatRisk continue today with an Extreme Heat Warning in effect
through this evening for much of the area.

Meanwhile, a shortwave trough currently pushing into northern
California will continue to propagate eastward through the Great
Basin and into Utah/northern Arizona going into early Tuesday. While
this disturbance will be weak, it will help to flatten the
subtropical ridge and somewhat push it to the south, leading to
height falls and a slight drop in temperatures for Tuesday. Guidance
show 500 mb heights decreasing to around 590 dm with afternoon highs
slightly decreasing ~2-3 degrees to 108-113 degrees across the lower
deserts Tuesday. Temperatures then begin to trend back up
Wednesday following the passage of the trough as the subtropical
ridge builds back over the Desert Southwest. Ensemble guidance
show 500 mb heights rising for the middle part of the week before
peaking around 592-594 dm by Thursday. Thursday will be the
hottest day for most areas later this week as forecast highs rise
to around 112-116 degrees. This will lead to widespread Major
HeatRisk across south-central Arizona Thursday. Thus, new Extreme
Heat Warnings have been issued. Despite the absence of Major
HeatRisk on Tuesday, have decided to go ahead and extend the
Extreme Heat Warning for the Phoenix metro through Friday as
temperatures don`t lower much and will remain near Major HeatRisk
thresholds. Temperatures Wednesday and Friday will be quite
similar to each other and will flirt with Major HeatRisk
thresholds. Thus, after Tuesday the Extreme Heat Warning will
expand to include most of south-central Arizona Wednesday through
Friday.

Temperatures begin to trend down Friday as a potent Pacific trough
pushes into the western CONUS. By Saturday, forecast highs drop
below 110 degrees for most lower desert locales. This trough
should continue to keep lower heights over our region into early
next week with temperatures eventually dropping to around or even
a few degrees below normals. Models have been trending toward a
stronger trough as well as a slower progression, likely keeping
dry air over most if not all of our region. Modest monsoon
moisture over Mexico still tries to push northward into far
southeast Arizona by early next week, but with the trough
providing southwesterly dry flow this moisture will have a hard
time gaining any foothold within our region.

&&

.AVIATION...Updated at 2330Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major aviation concerns through the TAF period under clear
skies. Winds will follow typical diurnal patterns with periods of
variability between transition periods. Afternoon and early
evening gustiness 15-20 kts out of the westerly direction will
continue to be common through the period.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns will exist through the TAF period under
clear skies. Winds at KIPL favor the SE until a shift to the W
this evening 10-15 kts before subsiding late tonight. KBLH will
maintain a S to SW component into tonight before a W wind
tomorrow.

&&

.FIRE WEATHER...
Hot and dry conditions with some afternoon breeziness will
continue early this week. 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. 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 this evening for AZZ530>536-
     538-539-547-552>556-559>562.

     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...Extreme Heat Warning until 8 PM PDT this evening for CAZ562>567-
     569-570.

&&

$$

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