641
FXUS65 KPSR 052300
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
400 PM MST Tue May 5 2026

.UPDATE...Updated Aviation Discussion

&&

.KEY MESSAGES...

- Isolated showers and storms will remain possible mostly over
  the high terrain east northeast of the Greater Phoenix Area
  through the remainder of the afternoon.

- A pronounced warming and drying trend is expected over the next
  several days as a weather system departs the Desert Southwest
  and high pressure takes hold along the West Coast, leading to
  triple digits highs across the lower deserts as early as Friday.

&&

.SHORT TERM /TODAY THROUGH THURSDAY/...
An expansive cumulus field covered the entire forecast area early
this afternoon, with better vertical development over the eastern
half of the state, where modest instability (100-250 J/kg MLCAPE
from RAP analysis) is present. This has resulted in spotty showers
and storms forming over the mountains east of Phoenix and more
notably along/downstream of the Mogollon Rim. An upper level low
continues to draw nearer to the area and is currently spinning over
SoCal, bringing abundant cooler air aloft to aid in the development
of the cumulus across the region. Breezy conditions continue today,
as regional pressure gradients remain strong, particularly across
portions of Eastern AZ. Widespread gusts to between 15-30 mph have
been observed this afternoon, with locally stronger gusts in the
typically prone western/southwestern portion of Imperial County (30-
40 mph). An increase in westerly winds may occur around/after
sunrise for the southwest corner of Imperial County, with gusts
flirting near Advisory level for a few hours, but generally
localized to gaps in the terrain and just downstream of prominent
terrain features.

The main energy from the low will exit to the northeast on Wednesday
and will be absorbed by another larger scale trough that will
encompass most of the central and eastern CONUS. Meanwhile, a
trailing piece of energy is expected to become cutoff from the main
jet stream and form a new upper-level low across northern Sonora as
a ridge of high pressure builds across the west coast. This feature
will continue to gradually progress eastward through northern Sonora
through Thursday with no sensible weather impacts expected for our
region. As 500 mb height fields steadily rise with the building
ridge over the west coast, temperatures will be on a rapid warming
trend, warming into the middle 80s on Wednesday to middle 90s on
Thursday across the lower deserts.

&&

.LONG TERM /FRIDAY THROUGH MONDAY/...
The main story heading into the long term period will be a
prolonged heat episode that will materialize as triple digit highs
will be in place for several days. As the aforementioned ridge
continues to gradually build across the western CONUS,
temperatures will continue to gradually warm with lower desert
highs reaching the low 100s as early as Friday with widespread
highs in the low to mid 100s continuing through the weekend.
Heading into early next week, ensembles show the ridge
intensifying a bit more as 500 mb height fields near 590dm. This
will result in additional warming, with the latest NBM showing
widespread lower desert highs in the mid to upper 100s. With
temperatures heating up into the triple digits by the end of the
week and beyond, widespread Moderate HeatRisk will be in place
across most of the area. Thus, any vulnerable communities and
those participating in outdoor activities will need to take the
necessary heat precautions to avoid any heat- related illnesses.

&&

.AVIATION...Updated at 2300Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Other than some lingering marginal breeziness this evening, no
major aviation concerns are expected during the TAF period. Winds
will favor diurnal trends, with a later than usual switch to the E
around 10-12Z. FEW-SCT CU will gradually clear this evening, with
mostly clear skies prevailing through the reminder of the
forecast.

Dependent on smoke generation by the wildfire in Buckeye, W-SW winds
today may pull more smoke into central portions of Phoenix and could
impact slantwise visibility, especially this evening.

Southeast California/Southwest Arizona including KIPL and KBLH:
Lingering SW/W`rly breeziness this evening will be the main
aviation concern during the next 24 hours. Gusts at each terminal
will range close to 20-25 kt before speeds relax noticeably
overnight. FEW CU will be present this evening before skies
quickly clear around sunset.

&&

.FIRE WEATHER...
Below normal temperatures will prevail today and Wednesday across
the region as readings across the lower deserts will top out in
the upper 70s today and middle 80s Wednesday. Isolated showers and
storms remain possible through this afternoon, particularly
across the higher terrain areas east of Phoenix. Breezy conditions
will continue for today with afternoon/early evening gusts
peaking at 15-30 mph and locally higher in Western Imperial
County. MinRHs for this afternoon will remain elevated with values
bottoming out between 20-40%. Lighter winds as well as much
warmer temperatures and lower humidities are then forecast for the
latter half of the week and beyond as high pressure builds back
into our region. Although conditions for critical fire weather
will not be met, single digit MinRHs this weekend will combine
with well above normal temperatures (triple digit highs for the
lower deserts) and typical upslope breeziness with gusts 15-25 mph
to produce some areas of elevated fire danger.

&&

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

$$

SHORT TERM...Whittock/Lojero
LONG TERM...Lojero
AVIATION...RW
FIRE WEATHER...Whittock/Lojero