420
FXUS65 KPSR 251736
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1036 AM MST Wed Jun 25 2025

.UPDATE...Updated 18Z Aviation Discussion

&&

.KEY MESSAGES...

- Temperatures will again be a few degrees below normal today,
  before near to above normal readings return by Friday

- Dry conditions will overall prevail through the weekend with
  daily light afternoon and evening breezes

- Widespread Moderate HeatRisk is expected by this weekend, with
  localized Major HeatRisk and highs at or just above 110 degrees
  by the start of next week

&&

.DISCUSSION...
For the start of last week of June, the weather pattern has been
quite favorable to keep temperatures from getting out of hand.
Looking back over the last several years, we actually have not had
a bad heatwave during the last week of June. That`s not to say it
wasn`t hot, as the last week of June in 2024 saw average
temperatures of around six degrees above normal largely because
of very warm overnight temperatures due to an early influx of
moisture. However, we can at least say we have not had a 115
degree day in Phoenix during the last week of June since 2017.
This could change this year as we have 114 degrees forecast for
Monday. The last several days have been at or just below normal
due to a stalled out trough centered just to our northwest.
However, this trough is beginning to fill and allowing the air
mass over our region to gradually warm. This will continue to
happen through Friday with H5 heights rising from 582-585dm today
to 588-590dm on Friday. Forecast highs by Thursday reach into the
normal range and then above normal on Friday with readings topping
out between 105-108 degrees across the lower deserts. Any
moisture will continue to mainly be confined to New Mexico with
only very marginal moisture seeping into far eastern Arizona
providing the potential for a few isolated afternoon showers or
weak thunderstorms near the stateline each day through Friday.

Starting this weekend, the ridge is forecast to set up directly
over the region, likely centered over eastern Arizona and western
New Mexico. The ridge is also expected to strengthen by Sunday
with H5 heights peaking between 592-594dm for Sunday and Monday.
Fortunately, the forecast strength of the ridge is not abnormally
strong for this time of year, but it should be enough to push
daytime highs to just above 110 degrees on Sunday before likely
peaking between 110-114 degrees Monday. If guidance is
underplaying the strength of the ridge, that could push highs up
another couple of degrees with some locations potentially reaching
115 degrees Monday. As temperatures push to above normal by the
weekend, we will see widespread Moderate HeatRisk develop with
even some localized Major HeatRisk possible for Sunday and Monday.

Ensemble guidance then suggests the ridge will begin to shift more
to the north, centering itself over the Four Corners area by next
Tuesday. Once this shift occurs, it should allow for the flow in
the lower levels to turn out of the southeast into much of
Arizona. If guidance is correct with pushing the high center over
the Four Corners area, it would allow for a gradual uptick in
moisture across Arizona next week and likely our first decent
chances of monsoon convection by around the middle part of next
week. Some of this will also depend on a weak trough that is shown
setting up just to our northwest. For now, there remains a good
deal of uncertainty with the placements of the high center and the
trough, along with how much and when the moisture advects into
our region. We could start to see some isolated to scattered
eastern Arizona higher terrain convection as early as Monday or
Tuesday with some potential for convection into the lower deserts
as early as next Wednesday or Thursday.

&&

.AVIATION...Updated at 1730Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No major aviation concerns. Winds will follow typical diurnal
trends. The familiar afternoon gusts will be mostly dormant today,
especially compared to the past several days, but brief periods of
speeds in the low to mid teens could still be possible. While FEW-
SCT clouds can be seen in the distance our area will remain
mostly clear throughout the TAF period.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected throughout this TAF period.
Winds will follow typical diurnal trends with speeds generally AOB
10 kts. While likely not directly impacting sfc visibilities,
lofted smoke/haze may occasionally affect slantwise visibilities
during the morning and late afternoon/evening hours at KIPL. Other
than the lofted smoke/haze clear skies will persist through the
TAF period.

&&

.FIRE WEATHER...
No significant fire weather concerns are expected over the next
few days. Temperatures will continue to gradually warm day-to-
day, but readings should remain near to below normal through
Thursday. MinRH values will only range between 5-15% and
overnight recoveries will not offer much relief as values hover
between 20-40%. Winds will follow familiar diurnal trends with
typical afternoon breeziness, gusting mainly between 15-20 mph. By
the weekend, temperatures will warm to above normal with highs
potentially peaking above 110 degrees across the lower deserts by
Sunday. Eventually, the weather pattern should become more
favorable for increasing moisture and at least some scattered
high terrain showers and thunderstorms by around next Tuesday.
This may initially result a day or two of dry lightning concerns
before moisture and rainfall chances increases later next week.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&

$$

DISCUSSION...Kuhlman
AVIATION...Ryan/RW
FIRE WEATHER...Kuhlman