877
FXUS65 KPSR 041100
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
400 AM MST Thu Jun 4 2026

.UPDATE...
Updated Aviation

&&

.KEY MESSAGES...

- Above normal temperatures with moderate HeatRisk will prevail
through the remainder of the week before readings retreat closer to
normal by the end of the weekend.

- Other than a slight chance of a shower or thunderstorm this
afternoon over eastern Arizona, dry conditions under mostly sunny
skies will prevail through at least the middle part of next week.

- Locally breezy conditions will develop for the end of the week and
into the weekend, particularly across the lower Colorado River
Valley and higher terrain communities.

&&

.SHORT TERM /Today through Saturday/...
The Desert Southwest finds itself in the midst of a messy upper-
level pattern with areas of low pressure to the north and south, and
ridging to the east and west. In turn, conditions have been a bit
atypical for June for parts of eastern Arizona and western New
Mexico with convective activity spawning over high terrain areas
yesterday afternoon thanks to the presence of some unseasonably
enhanced low-level moisture levels. This moisture will stick around
for one more day, creating a favorable setup for another round of
convective activity. However, it will once again be limited in
scope, being confined mostly to the White Mountains and around
enhanced terrain features of Graham and Greenlee Counties. Much like
yesterday, a very isolated cell cannot be ruled out over far
southeastern Gila County. The main impacts from potential storms
will be some occasional lightning and gusty winds in excess of 35
mph. Any locations that find themselves under any rainfall will only
see minimal totals, generally 0.10" or less, but some localized
higher totals are not completely out of the question.

Even with this messy upper-level pattern, the regional height field
continues to run slightly above normal for early June. This, in
turn, will help to keep our thermal profile warmer than normal
during the back half of the week and into the weekend. Afternoon
highs this afternoon for many locations with flirt with some of the
highest readings we have seen so far this year as temperatures range
between 105-109 degrees for lower desert communities. Phoenix and El
Centro, CA forecasted highs are at the top of that range, so the
first 110 degree readings of the year for these areas cannot be
completely ruled out. On average, 110F is reached at these locations
on 6/11 and 6/14 respectively, so it would not be completely out of
left field if we do reach that mark this afternoon. The silver
lining in this that the NBM is not confident that we will get there,
giving only about at 10-15% chance for both Phoenix and El Centro.
Temperatures beyond tomorrow will follow a slight downtrend, falling
closer to normal for early June (which is around 100 degrees for our
three main climate sites) by the end of the weekend.

Interactions between a lingering area of low pressure, currently
over northern Mexico, and an eastern Pacific ridge will set the
stage for a day-to-day uptrend in regional wind strength starting
this afternoon. Breeziness will be marginal to start off and peak
gusts will only reach upwards of 25 mph around the Lower Colorado
River Valley. However, pushing closer to the weekend, another low
diving south from the Gulf of Alaska will also begin to squeeze the
pressure gradient, adding another layer to the interplay mentioned
above. This will create stronger and more widespread breeziness for
Friday and Saturday as gusts approach 25-30 mph for higher terrain
areas and previously mentioned communities near the Colorado River.
With afternoon humidity values only hovering around 5-10% the next
several afternoons, any enhanced gusts will result in periods of
elevated fire weather conditions.

&&

.LONG TERM /Sunday through Wednesday/...
It appears that ensembles have come into better agreement in terms
of the evolution of the previously mentioned Gulf of Alaska low.
Some friction remains, but trends point towards a weaker solution
that was being favored by the GEFS at this time yesterday. Both the
GEFS and ECMWF Ens show this closed low becoming an open wave and
extending from the British Columbia down the length of the Pacific
Coast, so there will likely be at least some influence from this
disturbance on the Desert Southwest. This influence will more than
certainly come in the form of continued breezy to locally windy
conditions through the end of the weekend and into the weekend. The
associated negative height anomalies will promote some slight
cooling, but the vast majority of lower desert highs will remain in
triple digit regardless. This trough will not provide anything in
terms of moisture flux, so with continued breeziness forecasted,
daily elevated fire weather risk is expected to extend at least into
next Monday for parts of the forecast area.

There appears to be better agreement, compared to 24 hours ago,
regarding the pattern toward the middle of next week. Clusters have
honed in on the continued presence of troughing across the Great
Basin, but where they differ is how strong this feature might be.
Some clusters even suggest cyclonic curvature collocated with
positive height anomalies over the Desert Southwest, perhaps keeping
breezy conditions in the forecast as well as triple digit
temperatures. There is still some wiggle room so things are likely
to change over the next few days. One thing that does appear certain
is continued dry conditions through at least the middle of next week.

&&

.AVIATION...Updated at 1100Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:

No major weather issues will exist through Friday morning with only
a few distant Cu/Cb over mountains of eastern Arizona. Behavior of
winds will be very similar to the past 24 hours with good confidence
of periods of nearly calm conditions in the morning, and modest
gusts mid/late afternoon. Any outflow winds from eastern Arizona
storms will likely be less robust than yesterday allowing a westerly
wind component to persist longer into the overnight across the
Phoenix metro.

&&

.FIRE WEATHER...
The threat for an isolated dry thunderstorm over southern Gila
County this afternoon is the main fire weather hazard in the short
term. Winds through this afternoon will follow typical diurnal
tendencies with typical afternoon upslope breeziness. Gusts pick up
Friday and into the weekend, mainly across the Lower Colorado River
Valley and high terrain areas of the eastern districts with readings
reach upwards of 25-30 mph. With daily MinRHs hovering close to 5-
10% for the majority of the region, even marginal breezes will
result in periods of elevated fire weather conditions. Isolated
instances of near critical to critical conditions can be expected
with localized higher gusts. Overnight recovery will offer very
little in terms of relief as MaxRHs run only between 15-45% for most
locations. Breezy conditions are likely to continue into the
weekend, perhaps even lingering into next week, potentially
resulting in a prolonged period of daily occurrences of elevated to
near critical fire weather conditions starting Friday.

&&

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

&&

$$

SHORT TERM...RW
LONG TERM...RW
AVIATION...18
FIRE WEATHER...RW