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471
FXUS65 KPSR 260525
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1025 PM MST Sat May 25 2024

.UPDATE...
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Updated 06Z Aviation Discussion.
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&&

.SYNOPSIS...
Another breezy afternoon will precede much more tranquil
conditions going through next week. The coolest temperatures over
the next week will be today, as a warming trend to above normal,
accompanied by triple digit highs across the lower deserts early
next week, will commence tomorrow. Otherwise, dry conditions under
mostly clear skies will continue during this period as well.

&&

.DISCUSSION...
Longwave troughing continues to engulf western CONUS, while clear
skies continue to dominate the region as the main dynamic energy
remains well north of the region. Temperatures remain considerably
below normal today (6-8 degrees), as the negative height
anomalies associated with this troughing feature traverses across
the region through tonight. Breezy to isolated windy conditions,
strongest in southwestern Imperial County, will continue this
afternoon, with winds gusting 20-35 mph this afternoon and
extending into the evening hours across the region. Looking ahead,
the general mid-level pattern evolution over the next several
days will be building heights across the region, with the warmest
temperatures of the year expected through the middle portions of
this upcoming week.

Warming conditions will commence tomorrow, as the troughing
feature currently anchored over the region will exit to the east.
Mid-level heights will quickly build going into early next week,
with the main ridge axis generally centered over Arizona. As a
result, temperatures will warm, with triple digit highs likely
(60-100%) across the lower deserts as early as Monday. Mid-level
heights will continue to build through the middle of the week
(heights peaking around 582-585 dam), with potential of highs 105
or greater peaking on Tuesday around 30-70% (greatest in the
Phoenix metro) across the lower deserts. Thus, the building heat
will result in areas (30-50% coverage) of Moderate HeatRisk by
Tuesday for the lower deserts, with the worst conditions mostly
across southeastern California and the Phoenix metro.

Heading into the latter portions of next week, ensembles are
trending towards weakening mid-level heights, as an anomalous
closed low traverses across the Pacific Northwest. A cooling
trend remains of high certainty, although the magnitude of
cooling remains more uncertain. Clustering analysis depicts some
pretty significant differences no later than Friday, where this
trough moves quickly across the Intermountain West, resulting in a
slight cooling trend, or a much deeper and slower moving trough,
which would result in a much cooler scenario. This much cooler
scenario would result in the potential for breezy conditions to
become more of a noticeable increase as well. Current clusters
favor the weaker troughing solution (50-70%), but, as noted
previously, the magnitude of cooling remains noticeably uncertain,
as the interquartile ranges of the NBM high temperatures have a
5-7 degree spread late next week and into next weekend.

&&

.AVIATION...
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Updated at 0523Z.

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

Winds will follow their typical diurnal patterns with speeds aob 7
kt. Extended periods of light and variable winds are expected,
especially at KSDL and KDVT. Skies will remain clear through
Sunday.

Southeast California/Southwest Arizona including KIPL and KBLH:

Winds will follow their typical diurnal patterns with extended
periods of variability. Speeds will be aob 9 kt through the TAF
period. Skies will remain clear through Sunday.
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&&

.FIRE WEATHER...
Locally elevated fire weather conditions continue this afternoon,
particularly over the high terrain of the eastern districts, as a
weak system helps to generate widespread breezy conditions. Gusts
over the high terrain of the eastern districts will peak between
25-30 mph, with isolated gusts potentially up to 35 mph. Gusts
will peak mostly between 20-25 mph this afternoon elsewhere across
the lower deserts. MinRH values will range between 10-20% today
and locally higher in the high terrain, and will drop to 10-15%
tomorrow. Overnight recoveries will be fair tonight at around 30-
50% and drop to 25-40% Sunday night. Hot and dry conditions will
persist after today, with generally lighter wind speeds and
typical afternoon breeziness each day. Daily highs will reach the
century mark in many lower desert locations by Monday and values
generally top out between 100-105 through the middle of next week.

&&

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

$$

DISCUSSION...Young
AVIATION...Berislavich
FIRE WEATHER...Young/Whittock