089
FXUS65 KPSR 261725
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1025 AM MST Thu Jun 26 2025

.UPDATE...Updated 18Z Aviation Discussion

&&

.KEY MESSAGES...

- Temperatures will gradually heat up into the weekend reaching
  to above normal levels with widespread Moderate HeatRisk across
  all areas by Sunday

- Extreme Heat Watch is in effect for the Phoenix metro Sunday
  through Tuesday with areas of Major HeatRisk and high
  temperatures topping 110 degrees

- Dry conditions will prevail through at least the weekend, but a
  gradual increase in moisture next week is likely to lead to
  increasing chances for showers and thunderstorms by the middle
  to latter part of the week

&&

.DISCUSSION...
A dry air mass remains in place across all of southern California
and Arizona as the stationary trough over the region continues to
erode. This feature should still be recognizable through the rest
of today, but as it continues to fill we will begin the process of
warming up. After the below normal highs yesterday of around or
just over 100 degrees, we are expecting highs back into the normal
range today and even a few degrees above normal on Friday. By
Friday night into Saturday, the sub-tropical ridge will quickly
become the dominant weather feature over our region with H5
heights rising to near 590dm. With the dry air mass remaining over
the region, the high pressure ridge will push daytime highs to
around 110 degrees by Saturday resulting in widespread Moderate
HeatRisk across the area.

Once the ridge fully settles back over our region this weekend,
guidance shows it strengthening a bit further Sunday into Monday
with H5 heights likely peaking between 591-593dm on Monday. This
should easily push daytime highs to over 110 degrees for Sunday
and Monday and likely even into Tuesday if the ridge stays in
place. NBM temperature guidance shows highs peaking on Monday
between 111-115 degrees across the lower deserts with areas of
Major HeatRisk focused over the Phoenix Metro. An Extreme Heat
Watch remains in effect for the Phoenix area for Sunday-Tuesday.
This time around, the heat episode is likely to be accompanied by
higher moisture levels as we will begin to see surface dew points
creep upward into the 40s for Sunday and Monday to as high as the
lower 50s for Tuesday. The marginally higher humidities are likely
to keep overnight lows quite warm starting Sunday night with KPHX
potentially seeing it`s first 90 degree low of the season.

This next heat episode is likely to meet its end by next
Wednesday, not fully due to the ridge getting displaced out of
the region or weakening, but also because of our first good dose
of monsoon moisture advecting into the region from the southeast.
Guidance has been consistent in showing modest sub-tropical
moisture advecting first into southeast Arizona Monday and Tuesday
and then likely into south-central Arizona by next Wednesday and
Thursday. This moisture advection is likely to be partially aided
by an increase in southerly flow in between a weak Pacific trough
that develops just off the California coast Sunday into Monday and
the ridge to our northeast. This should help to gradually
increase moisture over our region into the middle part of next
week with high terrain convection possible as early as Tuesday and
maybe into the south-central lower deserts as early as Wednesday.
By late next week, we may even be able to see some deeper
tropical moisture seep into portions of our area, but this will be
dependent upon what happens with a potential Tropical Cyclone
south of Baja during the middle part of next week. If we do end up
seeing some tropical moisture at some point late next week, right
now it looks to fall on around next Friday. There are still a lot
of what-ifs, but we can at least point toward the 6-10 day CPC
outlook which shows a 70-80% chance of above normal precipitation
late next week. We will hopefully have a better idea on our
rainfall potential over the next few days.

&&

.AVIATION...Updated at 1725Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
No aviation weather concerns are expected during the TAF period.
Another similar pattern today as winds will continue to follow
typical diurnal shifts. Seasonal afternoon sporadic gusts in the
mid to upper teens will develop during the afternoon hours. Only
clouds present over the region will be a FEW mid-level clouds to
the far east of the terminals.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected during the TAF period. Winds
will continue to follow diurnal trends, with some occasional
breeziness at KBLH in the afternoon. While not directly impacting
sfc visibilities, lofted smoke/haze may occasionally affect
slantwise visibilities during the late afternoon/evening hours at
KIPL.

&&

.FIRE WEATHER...
High pressure will gradually strengthen across the region through
the weekend leading to a strong warming trend and continued dry
conditions. Temperatures will warm to above normal starting Friday
before peaking early next week. Expect little change in humidity
trends as MinRH values continue to range between 5-15% each day
and overnight recoveries stay between 20-35%. Winds will follow
familiar diurnal trends with typical afternoon breeziness, gusting
mainly between 15-20 mph. 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...Extreme Heat Watch from Sunday morning through Tuesday evening
     for AZZ537-540-542>544-546-548-550-551.

CA...None.
&&

$$

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