583
FXUS65 KPSR 052322
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
420 PM MST Sun May 5 2024

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
A dry weather system currently moving just north of the region will
promote breezy to windy conditions along with slightly cooler than
normal temperatures today. The weather pattern heading into the
upcoming week will feature seasonably dry conditions and
temperatures gradually rebounding to near normal range as well as
breezy conditions each afternoon.

&&

.DISCUSSION...
Latest water vapor satellite imagery depicts a potent upper-level
low pressure system moving across the northern Great Basin with its
base extending into the Desert Southwest. This is leading to a
tightening of the pressure gradient and thus enhanced winds through
this afternoon into the early evening hours. Peak wind gusts upwards
of 30 to 35 mph are likely across most of the lower desert
communities, with localized gusts upwards of 40-45 mph across
portions of southeast CA, especially Imperial County, as well as the
higher terrain areas to the north and east of Phoenix. The strong
winds will result in some elevated fire weather concerns as well as
areas of blowing dust, especially across the western deserts. In
addition to the gusty winds, high temperatures this afternoon will
be noticeably cooler with highs topping out in the mid 70s to low
80s across the western deserts to mid to upper 80s across the south-
central AZ lower deserts, including the Phoenix metro area.

The upper-level low pressure system by Monday will have quickly
moved east-northeastward into the Plains states. Winds will be
noticeably lighter compared to today and temperatures will be
noticeably warmer across the western deserts with highs rebounding
in the middle 80s while remaining steady state across the south-
central AZ lower deserts in the mid to upper 80s. The weather
pattern heading through the middle of the week will feature a broad
trough extending from the Plains states through the Pacific
northwest with the southern fringes clipping the Desert Southwest.
Under this pattern, our region will be situated in mostly zonal flow
with temperatures only gradually rising into the lower 90s while at
the same time the flow aloft will be strong enough to produce breezy
conditions with afternoon and early evening gusts in excess of 20-25
mph.

Both the deterministic and ensemble model suite by the latter half
of the week are indicating that as an upper-level ridge begins to
build near the Pacific northwest coast, a piece of energy from the
aforementioned trough is expected to break off and retrograde close
to our region heading into Thursday and Friday. Not much in the way
of sensible weather impacts are expected from this feature other
than continuing the breezy conditions as well keep the upper-level
heights suppressed to maintain temperatures from rising even
further. Eventually, as the upper-level ridge axis builds further
east and displaces the shortwave trough eastward sometime next
weekend, heights aloft will rise accordingly. This will lead to
temperatures rising further, with latest NBM guidance showing
widespread highs in the upper 90s across the lower deserts with a 20-
40% of approaching 100 degrees.

&&

.AVIATION...Updated at 2320Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Gusty west winds prevailing well into the evening hours will be the
greatest weather issue as thicker cirrus cigs gradually clear. Gusts
around 25kt should be common into the mid evening before slow
decoupling and weakening speeds. Forecast confidence is very good
that a W/NW component will continue much later into the overnight
than is typical, with some locations potentially never truly
switching to the traditional morning easterly. Nevertheless,
widespread westerlies will prevail again by late morning with only
limited afternoon gusts.


Southeast California/Southwest Arizona including KIPL and KBLH:
Gusty winds this evening will remain the primary weather concern
under clear skies. Gusts around 30kt into the early evening should
quickly weaken with moderate forecast confidence that gusts abate by
mid/late evening. Strong winds have generated lofted blowing dust
which may lead to some slantwise visibility reductions around
sunset. Otherwise, trends in directions suggest a more northerly
component into the overnight hours, then becoming more variable in
direction Monday afternoon.

&&

.FIRE WEATHER...
A weather system moving just to the north of the region today will
bring breezy to windy conditions areawide. Wind gusts of 25-35 mph
are likely in many areas this afternoon with upwards of 40-45 mph
possible across portions of southeast California and over the high
terrain north and east of Phoenix. The strong winds and dry
conditions with humidities as low as 20% today could lead to
elevated fire weather conditions. Lighter winds are expected by
Monday with MinRHs lowering to around 10%, with overnight recoveries
of 20-50%. Weak high pressure will then remain over the region
through much of the coming week as temperatures return to slightly
above normal by late week. Seasonably dry conditions are expected
this week with MinRHs dropping to around 10% each day starting
Monday. Winds this week will be fairly light most days, except for
Tuesday and Wednesday when winds will be more elevated with
afternoon gusts between 20-30 mph in some areas.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 8 PM PDT this evening for CAZ563>567.

     Wind Advisory until 11 PM PDT this evening for CAZ562.

&&

$$

DISCUSSION...Lojero
AVIATION...18
FIRE WEATHER...Kuhlman