438
FXUS65 KPSR 101112
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
410 AM MST Fri May 10 2024

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
A warming temperature trend going through the weekend will result in
above normal temperatures and increasing chances of triple digit
highs across the lower deserts going into next week. Otherwise, dry
conditions will persist, with afternoon breeziness continuing to
cause areas of elevated fire weather conditions over the next
several days.

&&

.DISCUSSION...
Early morning satellite depicts few to scattered high clouds spread
out across southern Arizona, while water vapor imagery shows a
persistent east to west oriented longwave trough entrenched across
western CONUS. This trough has been responsible for keeping
temperatures at or below normal over the last several days. However,
this trough is expected to weaken over the next few days, as
anomalously strong ridging that is currently over the Pacific
Northwest impinges on this trough. However, negative or neutral
height anomalies will continue to persist over the next several
days, so while a warming trend will occur, it will mute the absolute
maximums of this warming trend to the low 100s at most through early
next week.

Ensembles have hedged towards stronger negative height anomalies to
persist across the region through the middle of next week, resulting
in lower probabilities of 100 degree highs for the Phoenix area to
generally a 30-50% range through most of next week. Generally
speaking, the warmest day based on the deterministic NBM forecast
will be Sunday (Monday) for the western (eastern) districts as the
trough weakens during this period before reestablishing its position
as the aforementioned ridging flattens out early next week. Winds
will continue to be breezy during the afternoon hours as westerly
flow persists through this period, resulting in areas of elevated
fire weather conditions when combined with the very dry conditions
(minimum RH`s in the 10-15% range), mainly in higher terrain areas
where the gustiness will generally be stronger.

Looking towards late next week, ensembles continue to show
potentially more robust ridging building into the Desert Southwest
going into next weekend. However, ensembles show considerable spread
in regards to a troughing feature that may dig southward across
Alberta and Saskatchewan, which could dampen the strength of this
ridge. Thus, temperature trends are a bit more uncertain, as chances
for highs exceeding 100 degrees seem higher, but should the more
robust troughing occur, high temperatures staying below 100 degrees
would be a near certainty.

&&

.AVIATION...Updated at 1110Z.

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

No major weather issues will exist through Saturday morning under
only a FEW passing cirrus decks. Wind trends will be very similar to
the past several days, though with somewhat less afternoon gustiness
(only around 15kt). Periods of variable winds will also be common,
especially during times of wind shifts and the late night/early
morning hours.

&&

.FIRE WEATHER...
Temperatures are expected to warm over the next several days, with
chances for highs reaching 100 degrees increasing above 50%, at
least for the western districts, by late this weekend. Temperatures
are expected to remain above normal going through early next week.
MinRHs will be in the 5-10% across the lower deserts and in the 10-
15% range across the higher terrain through this weekend. Overnight
recovery will be poor in the 20-40% through tonight, before improved
recoveries in the 30-60% range heading into early next week. Typical
springtime breeziness continues through the weekend with afternoon
and early evening wind gusts of 20-25 mph. These breezy conditions
combined with dry fine fuels, and low RHs will likely create some
elevated fire weather conditions. Dry conditions persist into next
week.

&&

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

&&

$$

DISCUSSION...Young
AVIATION...18
FIRE WEATHER...Young/Berislavich