459
FXUS65 KPSR 222341
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
441 PM MST Fri Nov 22 2024

.UPDATE...Updated 00z Aviation Discussion.

&&

.SYNOPSIS...
High pressure over the region will promote well above normal
temperatures with lower desert highs in the upper 70s to around 80
degrees through Saturday. Pacific moisture aloft will lead to
increasing cloud cover starting Sunday, which will result in warmer
overnight lows. For the first half of next week, temperatures are
expected to gradually fall to near normal under mostly cloudy skies.
Any precipitation chances during the early to middle part of next
week will be confined to the higher terrain of Northern Arizona.

&&

.DISCUSSION...
Warm, quiet weather conditions continue across the Southwest as an
upper level ridge remains situated over the region. Afternoon
visible satellite imagery showed mostly clear skies persisting over
Arizona with dry westerly flow aloft in place. While dry conditions
persist over the region, above normal temperatures remain in place
thanks to the upper level ridge. Objective analysis this afternoon
showed 500 mb heights between 583-585 dm, which is around the 90th
percentile for this time of year. A warm afternoon is underway as
temperatures climb into the the upper 70s for many areas across
southwest Arizona and southeast California to low 80s across south-
central Arizona. Above normal temperatures will persist into
Saturday before cooling closer to seasonal normals Sunday.

While dry, warm conditions continue locally into the start of the
weekend, unsettled weather continues along parts of the West Coast.
IR satellite imagery show several different areas of low pressure
spinning off the coast of the Pacific Northwest while an
atmospheric river continues to impact northern portions of
California. The Pacific Northwest troughing will propagate further
south and east and suppress ridging over the Southwest, promoting
zonal flow aloft over the region late this weekend into early next
week. The current aforementioned atmospheric river will weaken as
it pushes further south, but a reinforcing push of Pacific
moisture will arrive into southern California early next week.
Despite PWAT anomalies for our area climbing upwards of 150-200%
early next week with this moisture, forecast soundings show this
moisture remaining confined to the mid and upper levels of the
troposphere, while drier conditions persist in the boundary layer.
The lack of better boundary layer moisture along with the lack of
forcing will limit any rain chances across the area with
increasing expansive cloud cover being the most likely outcome.

Ensemble cluster analysis show good agreement that a closed low
will become an open wave as it propagates southeastward into the
Four Corners region going into the middle part of next week. The
best dynamics with this shortwave are favored to remain well north
of our area and thus the best rain chances will remain north.
Latest NBM PoPs keep rain chances less than 10% through the next
week across the CWA. While rain chances remain low, cloudy skies
will increase starting Sunday with lower desert highs cooling into
the mid 70s. Overnight lows will, however, trend upward into the
mid 40s to mid 50s starting this weekend and continuing into early
next week due to the thick cloud cover.

&&

.AVIATION...Updated at 2340Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT; and
Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation weather concerns are expected through Saturday
afternoon under mostly clear skies, with some high cirrus mainly
to the south of the region. Light winds, AOB 5 kt, with extended
periods of variability and even calm conditions will be common.
More traditional diurnal tendencies across the Phoenix sites are
anticipated tonight and tomorrow.

&&

.FIRE WEATHER...
High pressure will persist over the region with temperatures
running several degrees above normal through Saturday until
increasing cloud cover brings temperatures closer to normal by
Sunday. 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 above 30% 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...Young/Whittock
FIRE WEATHER...Salerno