376
FXUS65 KPSR 082300
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
400 PM MST Tue Oct 8 2024

.Update...Updated Aviation Discussion

&&

.SYNOPSIS...
Record level temperatures will continue over the next week,
although temperatures will cool gradually going into early next
week. Dry conditions will also persist, with periods of increased
cloud cover as a couple of decaying weather systems bypass the
region to the north.

&&

.DISCUSSION...
Mostly clear skies continue to persist across the region this
afternoon, although more noticeable cumulus fields are more
widespread relative to the past several days as some increasing
moisture levels advect into the Desert Southwest. This increased
moisture is due to a weak troughing feature situated across the
southern California coast that is gradually migrating eastward
onshore over the next 24 hours. While there is an increase in
moisture levels, there is no discernible rain threat over the
next couple of days (and beyond).

The story of the weather pattern continues to be record heat,
where the afternoon high temperatures have now reached 15
consecutive days of either tying or breaking the daily high record
temperature for central Phoenix. The first week of October is
running almost 14 degrees above normal and was over 7 degrees
hotter than the previous hottest first week of October in 2020.
Anomalously strong ridging will remain overhead for the better
part of the next week, with some ebbs and flows of the pattern due
to some shortwaves protruding out of the Pacific Northwest.
Otherwise, temperatures will slowly cool over the next week as
this ridge gradually weakens.

At about the 6-7 day mark, a strong closed low in the Gulf of
Alaska will begin to dig southward into the eastern Pacific,
representing the best chance at dislodging the persistent ridge
going into the middle of next week. Most ensemble clusters show
this pattern change coming to fruition, which cause a much more
substantial cooling trend starting late next week, with some rain
potential...so will have to keep an eye on the evolution of that
potential scenario. Otherwise, expect temperatures to continue to
remain well above normal, with the first sub-100 high temperature
not expected, at least for the Phoenix metro, until at least early
next week.

&&

.AVIATION...Updated at 2300Z.

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

No aviation concerns are expected during the TAF period. Winds
will follow light and diurnal tendencies, with extended periods of
variability during the morning hours for the CA terminals. FEW to
perhaps SCT mid and upper level clouds will be present over metro
Phoenix terminals through tomorrow, while generally clear skies
will prevail further west.

&&

.FIRE WEATHER...
Hot and dry conditions will persist through the rest of the week
with daily record highs persisting through at least mid week.
There will be a gradual cooling trend, but temperatures will
remain well above normal. Daily MinRHs of around 10% can be
expected across the lower deserts to around 15% in the higher
terrain. Expect overall light winds over the next several days
following typical diurnal patterns.

&&

.CLIMATE...

Record highs through Friday:

Date        Phoenix         Yuma         El Centro
----        -------         ----         ---------
Oct 8     104 in 1987    107 in 1996    106 in 1996
Oct 9     103 in 1996    106 in 1996    104 in 1996
Oct 10    105 in 1991    107 in 1991    105 in 1996
Oct 11    102 in 1991    107 in 1950    106 in 1995
Oct 12    103 in 1950    109 in 1950    106 in 1965
Oct 13    101 in 1989    105 in 1958    104 in 1999

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST this evening for AZZ537-
     540>544-546-548>551.

CA...Excessive Heat Warning until 8 PM PDT this evening for CAZ562-
     566.

&&

$$

DISCUSSION...Young
AVIATION...RW
FIRE WEATHER...Kuhlman
CLIMATE...Young/18