544
FXUS65 KPSR 301356
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
418 AM MST Mon Jun 30 2025

.UPDATE...Updated Aviation Discussion...

&&

.KEY MESSAGES...

- Extreme heat conditions expected through Tuesday across the
  lower deserts as high temperatures top out between 110-117 degrees,
  with Extreme Heat Warnings in effect as areas of Major HeatRisk
  develop.

- An influx of monsoonal moisture will lead to increasing chances
  of showers and thunderstorms, mainly during the Tuesday-Thursday
  time frame across portions of AZ, with the best chances for
  activity confined across the higher terrain areas.

- A decrease in moisture will lead to a significant decrease in
  shower and thunderstorm activity during the July 4th Holiday
  Weekend along with near normal temperatures.

&&

.DISCUSSION...
Latest water vapor satellite imagery as well as streamline analysis
reveal the subtropical high situated near the AZ/NM border with
an upper-level low situated just off the coast of southern CA.
With the presence of the subtropical high over the area with 500
mb height fields ranging between 590-593dm, the major concern during
the next couple of days will be the extreme heat conditions. High
temperatures this afternoon are expected to peak between 112-117
degrees across the lower deserts, leading to widespread Major
HeatRisk. For the Phoenix area, there is a high probability, >70%
chance, of the record high of 115 degrees set back in 2013 and 1979
to be broken. Temperatures on Tuesday will be a degree or two cooler
than today but still very hot as afternoon highs top out between 110-
114 degrees, with areas of Major HeatRisk continuing across the
majority of the lower deserts. As a result, the Extreme Heat
Warnings will continue in effect through Tuesday evening. Therefore,
it is very essential to take all the necessary heat precautions to
avoid any heat-related illnesses.

The combination of the subtropical high migrating over the Four
Corners Region and the aforementioned upper-level low just off
the southern CA coast will help advect a modest amount of moisture
through midweek across the region. As a result of the increase in
moisture, shower and thunderstorm activity will be increasing in
coverage each day through Wednesday. For later today, thunderstorm
activity that develops will be confined mainly to the eastern
third of AZ, with outflows from the activity likely to be directed
westward into the lower elevations. The latest HREF, gives a
30-50% chance of wind gusts exceeding 35 mph across as far west as
far eastern Maricopa and northern Pinal Counties later this
evening.

The best chances for thunderstorm activity across south-central AZ
will most likely be during the Tuesday-Wednesday timeframe.
Thunderstorm activity on Tuesday afternoon/evening will be
concentrated mainly across portions of southern Gila County through
the higher elevations of eastern Maricopa and northern Pinal
Counties. Across the lower deserts, strong inhibition will likely
limit any thunderstorm activity, however, with DCAPE values
approaching 1500 J/KG, the environment will be conducive for
strong, gusty outflow winds and areas of blowing dust. The best
chances for thunderstorm activity across the lower deserts of
south-central AZ, including the Phoenix area, is likely Wednesday
evening through early Thursday as moisture levels peak with PWATs
approaching 1.2-1.3", resulting in weaker inhibition. In addition,
upper-level forcing from the approaching upper-level trough will
also increase. As of right now, NBM PoPs during this time frame
across the lower deserts range between 20-40%.

As the upper-level trough traverses the Desert Southwest on
Thursday, westerly flow aloft will begin to scour out the moisture
from west to east, leading to a downtrend in thunderstorm activity
beginning Thursday afternoon into Friday with the drier airmass
remaining in place through next weekend. As a result, it is looking
likely that the entire July 4th Holiday Weekend will remain storm-
free across the region. With the decreasing heights aloft from the
approaching trough, temperatures are expected to take a noticeable
downward trend mid to late week. Temperatures on Wednesday are
expected to be near normal, before dropping a couple of days below
normal Thursday and Friday. As heights aloft increase once again
next weekend, temperatures will be on a slight upward trend,
however, remaining below 110 degrees.

&&

.AVIATION...Updated at 1120Z.

South Central Arizona including KPHX, KIWA, KSDL, KDVT:
Little to no aviation impacts are expected through Tuesday morning.
Typical diurnal wind patterns with some westerly breeziness are
expected through this evening. Starting around midnight tonight,
expect easterly winds at around 10 kts with some gustiness at
times through Tuesday morning. Skies will remain clear to mostly
clear with some FEW to SCT decks around 15-18K feet.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation impacts are are expected through the period. West
winds will continue to prevail at KIPL, while KBLH will generally
see north northwest winds during the overnight and morning hours
and south to westerly winds during the afternoon and evening.
Skies will remain clear to mostly clear with some FEW decks around
15-18K feet.

&&

.FIRE WEATHER...
Very hot conditions will persist through Tuesday as temperatures
across the lower deserts exceed 110 degrees. MinRHs will remain
between 5-15% today with the overall wind pattern following the
familiar diurnal tendencies with some afternoon upslope gustiness.
Low-level moisture will increase Tuesday-Wednesday, with MinRH
values climbing to 20-25% across the eastern districts. The
moisture increase will also lead to increasing chances for shower
and thunderstorm activity across the higher terrain areas of
south-central AZ starting on Tuesday with gusty outflow winds
affecting the lower deserts. There will be some initial concerns
for dry lightning activity before a further increase in moisture
levels leads to a better potential for wetting rains by midweek.
Storm chances diminish by the end of the week through next weekend
as drier filters into the region along with a decrease in MinRH
values.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Extreme Heat Warning from 10 AM this morning to 8 PM MST Tuesday
     for AZZ530>536-538-539-553-554-559.

     Extreme Heat Warning until 8 PM MST Tuesday for AZZ537-540-
     542>544-546-548-550-551.

     Extreme Heat Warning from 10 AM this morning to 8 PM MST this
     evening for AZZ541-545-547-549-552-555-556-560>562.

CA...Extreme Heat Warning from 10 AM this morning to 8 PM PDT Tuesday
     for CAZ562-565>567-569-570.

&&

$$

DISCUSSION...Lojero
AVIATION...Kuhlman
FIRE WEATHER...Lojero