320
FXUS65 KPSR 052007
AFDPSR

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

.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 1810Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

Westerly to southwesterly winds are now in place this morning at the
TAF sites and will continue to become increasingly breezy through
the afternoon. By around 20Z, gusts are expected to climb upwards of
25-30 kts with a few gusts in excess of 30 kts. Gusty winds will
linger into the evening hours as a cold front pushes through the
region before winds weaken following the FROPA. Can`t rule out some
slantwise visibility concerns if today`s strong winds generate
lofted dust across the region. Light winds under 10 kts prevail
going into the overnight period, but directions are not expected to
make the typical diurnal easterly shift. Instead, westerly winds are
expected to hold into the overnight period with some light and
variable winds by early Monday morning. Otherwise, SCT-BKN clouds
generally aoa 10 kft will give way to mostly clear skies later this
evening.

Southeast California/Southwest Arizona including KIPL and KBLH:

Winds will remain the primary aviation weather concern for today.
Strong westerly winds gusting to around 35 kts will continue through
the afternoon at KIPL before gradually weakening going into this
evening. Winds at KBLH won`t be as strong, though a few gusts up to
around 35 kts will be possible through this afternoon. Winds at KBLH
will veer toward the northwest around 01Z as a cold front pushes
through the region before strong gusts subside following the
FROPA. Strong winds today may generate lofted blowing dust, which
may lead to slantwise visibility reductions and perhaps lowered
surface visibilities. SCT-BKN high clouds will give way to mostly
clear skies by this evening.

&&

.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...Smith
FIRE WEATHER...Kuhlman