173
FXUS65 KPSR 212040
AFDPSR
Area Forecast Discussion
National Weather Service Phoenix AZ
140 PM MST Thu Nov 21 2024
.SYNOPSIS...
High pressure over the region will bring slightly above normal
temperatures into the weekend with lower desert highs in the
upper 70s to around 80 degrees through Saturday. Dry conditions
will continue through at least the weekend with skies eventually
becoming fairly cloudy starting Sunday. For the first half of
next week, temperatures are expected to be near to slightly above
normal under mostly cloudy skies, while rain chances are
currently forecast to remain less than 10% for most places.
&&
.DISCUSSION...
The latest visible and IR satellite imagery show a well-defined
upper level low spinning off the Pacific Northwest coast while an
atmospheric river brings excessive rainfall to northern California.
Across the Desert Southwest, an upper level ridge continues to
dominate our weather with dry, tranquil conditions persisting.
Today, 500 mb heights will peak upwards of 586-588 dm, which is
above the 90th percentile for this time of year. As a result,
temperatures will warm upwards of 4-9 degrees above seasonal
normals as high temperatures across the lower deserts top out in
the upper 70s to low 80s today and tomorrow. Cool overnight lows
will remain in the 40s to around 50 degrees with a few colder
spots dipping into the 30s over the next couple of mornings. Above
normal temperatures will persist into the weekend, while skies
are forecast to remain mostly clear through Saturday with some
passing cirrus at times.
Ensemble guidance show good agreement that heights will gradually
lower through the weekend into the beginning of next week as the
current eastern Pacific longwave troughing pushes further south and
east. As this occurs, the ongoing AR will push toward the south
while weakening before a second weaker AR pushes into southern
California and the southwest CONUS for the start of next week. This
will usher in mid and upper level moisture and promote expansive
cloud cover over our area for the start of the new week. Despite
the increase in moisture with ensemble PWAT anomalies climbing
upwards of 150-200%, the lack of boundary layer moisture and
forcing mechanisms will limit rain chances across the region with
NBM PoPs remaining below 10% early next week. Ensemble cluster
analysis indicate the potential for a shortwave trough to
propagate southeastward into the Four Corners region heading into
the middle part of next week. Currently, the best dynamics with
this system are favored to remain to our north with much higher
PoPs focused over the Arizona high terrain during the
Tuesday/Wednesday timeframe. For now, the most likely outcome for
our area will be to have overall cloudy skies starting Sunday,
with near to slightly above normal temperatures persisting into
the middle part of next week as forecast highs top out in the mid
70s. Overnight lows will trend upward into the mid 40 to mid 50s
starting this weekend and continuing into early next due to the
thick cloud cover.
&&
.AVIATION...Updated at 1740Z.
South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns will exist through Friday morning
under periods of high clouds and otherwise mostly clear skies.
Light wind speeds, AOB 6 kts, will persist, with N-NW flow
developing in the early to mid afternoon before shifting to the E
later in the evening.
&&
.FIRE WEATHER...
High pressure will persist across the region into the weekend
with temperatures running a few degrees above normal. Dry
conditions are expected through at least Saturday with MinRHs
around 10% across the lower deserts to 15% in higher terrain
areas before humidities increase Sunday into early next week
under fairly cloudy skies. The weather pattern will continue to
support overall light winds with only some periodic light breezes
mainly during the morning hours and focused along ridgetops.
&&
.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...None.
&&
$$
DISCUSSION...Smith
AVIATION...Whittock
FIRE WEATHER...Kuhlman
View a Different U.S. Forecast Discussion Location
(In alphabetical order by state)
|
|