171
FXUS65 KPSR 300901
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
201 AM MST Mon Sep 30 2024

.SYNOPSIS...
High pressure entrenched across much of the western United States
will continue to promote dry and unseasonably hot conditions,
with record heat likely persisting into the end of the week.
Temperatures will begin to cool slightly by the upcoming weekend,
but any noticeable relief from these excessively hot conditions
is not expected for the foreseeable future.

&&

.DISCUSSION...
Early morning atmospheric analysis reveals stubborn high pressure
encompassing much of the Four Corners, while two areas of
troughing flank the region. The stronger of the two disturbances
will pass too far to the north to bring any sensible impacts to
day-to-day conditions for our forecast area. Same can be said
about the upper-low centered over southern California as that will
eventually dissolve into the broader flow pattern. A marginal
increase in moisture will result in a few more clouds over the
region compared to what was seen over the past few days, and may
even promote a few isolated showers over the White Mountains
during the next few afternoons. However, any rainfall across our
CWA appears unlikely, as max PoPs are only around 10% for far
southeastern Gila County.

With ridging overhead, mostly dry and unseasonably hot temperatures
will be the norm over the next several day and potentially into
the upcoming weekend. Temperatures across the lower deserts
through Friday are anticipated to hover between 103-111 degrees
each day, which is a good 10-15 degrees above normal for this time
of year. Phoenix Sky Harbor Airport has already seen six
consecutive daily record highs broken, and it appears likely that
streak will continue. As a result, the Excessive Heat Warnings
across the region have been extended through Friday evening. NBM
temperature projections indicate a slight cooldown by next
weekend, but relief from this anomalously hot stretch does not
appear likely for the next 7-10 days, barring any significant
shifts in forecast trends.

&&

.AVIATION...Updated at 0500Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No major aviation weather concerns are expected through the TAF
period. Wind directions will exhibit the more typical diurnal
tendencies with light speeds aob 8 kts. There will likely be
periods of directional variability, especially during the diurnal
transition. FEW-SCT mid-level cloud decks will be common through
Monday.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns under mostly clear skies are
expected through the TAF period. At KIPL, winds out of the west
currently will switch out of the southeast during the overnight
hours and remain out of the southeast through the remainder of
the period. At KBLH, winds will vary between the south to
southwest throughout the period. Extended periods of very light
and variable winds will be common.

&&

.FIRE WEATHER...
Dry and abnormally hot conditions will continue through this week
as a strong area of high pressure sits overhead. Lower desert high
temperatures will be between 103-111 degrees each afternoon.
MinRH values will run between 5-15% each afternoon, while
overnight MaxRH readings should range between 25-35%, with some
locally higher values across Yuma and Imperial Counties. Winds are
expected to follow typical diurnal trends, with occasional
afternoon breeziness near 20-25 mph.

&&

.CLIMATE...

Record highs this weekend and next week:

Date        Phoenix         Yuma         El Centro
----        -------         ----         ---------
Sep 30    107 in 2010    109 in 2020    108 in 2020
Oct 1     107 in 2020    110 in 1980    110 in 1980
Oct 2     107 in 1980    112 in 1980    108 in 2020
Oct 3     105 in 2020    108 in 1952    108 in 1952
Oct 4     105 in 2020    109 in 1952    106 in 1952
Oct 5     105 in 2020    108 in 1917    106 in 2020
Oct 6     105 in 1917    108 in 1980    106 in 1964
Oct 7     104 in 1991    108 in 1987    105 in 1991

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST Friday for AZZ530>544-546-
     548>551-553>555-559.

CA...Excessive Heat Warning until 8 PM PDT Friday for CAZ562-566-567-
     569-570.

&&

$$

DISCUSSION...RW
AVIATION...Lojero
FIRE WEATHER...RW
CLIMATE...18