South West Weather

549
FXUS65 KPSR 021111
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
411 AM MST Sat May 2 2026

.UPDATE...12Z Aviation Discussion.

&&

.KEY MESSAGES...

- Above normal temperatures with lower desert highs in the middle
  nineties will be common throughout the weekend.

- As a low pressure system approaches the region early next week,
  breezy to locally windy conditions, much cooler temperatures,
  and increased rain chances across the AZ high terrain can be
  expected.

- As the low pressure system departs the region and high pressure
  builds in by the latter half of next week, a rapid warming
  trend to above normal temperatures is likely.

&&

.SHORT TERM /TODAY THROUGH MONDAY/...
Early morning water vapor satellite as well as streamline analysis
show a ridge of high pressure enveloping the western CONUS while an
upper-level low is pivoting off the west coast. Meanwhile to the
east, a longwave trough is enveloping most of the eastern half of
CONUS with a trailing shortwave enveloping eastern AZ and NM,
resulting in a few light showers across far eastern AZ. As heights
aloft increase to 576-578dm from the ridge enveloping the western
CONUS, afternoon high temperatures both today and Sunday will top
out in the middle 90s across most of the lower desert locations. As
surface high pressure builds along the Southern Plains, an easterly
gradient will setup this morning and to a lesser extent on Sunday
morning, producing some gusty winds after sunrise as peak gusts
reach 15-25 mph across the lower elevations of south-central AZ and
locally higher upwards of 30-35 mph across the higher terrain areas
east of Phoenix.

The aforementioned upper-level low off the west coast will
continue to dig southward and become cutoff off the CA coast later
today. As the low slowly migrates eastward on Sunday, gradual
height falls will lead to an increase in breezy to locally windy
conditions across southwest AZ and southeast CA, where
afternoon/evening gusts between 25-35 mph will be common. Locally
higher gusts in excess of 40 mph are likely across the typically
wind prone areas of southwestern Imperial County.

Heading into Monday, the upper low will gradually move inland
through CA. With 500 mb height fields falling to between 568-572dm,
temperatures will cool rather significantly as afternoon highs will
only top out in the lower 80s across the western deserts to middle
80s across the south-central AZ lower deserts. With the height
falls and associated jet energy spreading eastward, the
afternoon/early evening breeziness will become more widespread to
include most of AZ. Additionally, the slow eastward migration of
the low will allow some moisture to advect northward into the
eastern half of AZ, with model guidance showing PWATs rising to
between 0.7-0.8" (~200% of normal). Therefore, the potential will
exist for scattered light showers to break out, especially across
the higher terrain areas of eastern AZ, late Monday night through
the first part of Tuesday, with NBM PoPs solidly into the 20-40%
range.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
As the the upper low moves through the Desert SW on Tuesday,
temperatures will cool even further with afternoon highs only
reaching the upper 70s to around 80 degrees across the lower
deserts. This will be a solid 10 degrees below normal for early
May. Breezy conditions will also remain in place across much of
the region. The low will finally exit to our east by mid week with
upper-level ridging building along the west coast. There are
indications from guidance that a piece of energy left behind from
the departing low could develop into a weak cutoff low over the
Baja Peninsula heading into the latter half of the week, but as of
right now it looks to be too far to the south to have any
sensible weather impacts for our region. With 500 mb height fields
rapidly rising to around 580dm from the building ridge,
temperatures by the latter half of the week will be on a rapid
warming trend. The latest NBM is showing afternoon highs across
the lower deserts rapidly warming from the middle 80s on Wednesday
to middle 90s on Thursday. Even further warming into the triple
digits, which would be the first occurrence since the
unprecedented early season heatwave from late March, is being
shown starting next Friday.

&&

.AVIATION...Updated at 1111Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation concerns are expected through the TAF period.
Easterly winds will prevail through most of the TAF period as the
typical afternoon westerly shift is unlikely to occur today.
Gusts up to 20-25 kts will be possible late this morning between
14-18Z. Winds will then relax heading into the afternoon and
evening hours. FEW high clouds will gradually increase to SCT-BKN
later in the period.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation concerns are expected through the TAF period.
NW/NNW winds will transition to E/NE by late this morning.
Afterwards, KIPL will become more westerly by late this evening,
while KBLH will go from SSE in the afternoon to SSW close to
midnight tonight. Wind speeds at both terminals should generally
remain aob 10 kts. FEW high clouds will gradually increase to SCT-
BKN later in the period.

&&

.FIRE WEATHER...
Dry conditions and above normal temperatures will be observed
through the weekend. A low pressure system will gradually approach
the CA coast late this weekend, resulting in widespread breezy to
locally windy conditions into early next week and temperatures
cooling into a below normal category Monday-Tuesday. Gusty
afternoon winds combined with low humidities will likely produce
elevated fire weather conditions Sunday for portions of the
western districts, including the Lower Colorado River Valley. As
the low pressure system moves through the Desert Southwest early
next week, the chance of showers will increase late Monday into
the first part of Tuesday across the far eastern districts,
however, the probability of wetting rains will remain on the low
side. Afternoon MinRHs between 8-15% will be common today,
increasing slightly into a 10-20% range Sunday and 15-30% range
early next week.

&&

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

$$

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