633
FXUS65 KPSR 230928
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
228 AM MST Thu May 23 2024

.SYNOPSIS...
Clear to mostly clear skies and dry conditions will prevail
through the holiday weekend with temperatures close to normal
through the weekend before warming early next week. The coolest
day should be Saturday with lower desert highs mostly in the
upper 80s with other days seeing readings mostly in the mid 90s.
Temperatures should then warm up to around 100 degrees by Memorial
Day and potentially as warm as 105 degrees by the middle of next
week.

&&

.DISCUSSION...
The synoptic pattern continues to support progressive weather
systems generally tracking across the northern half of U.S. with
the broad troughing extending as far south as the Desert
Southwest. Current water vapor imagery shows one weather system
tracking east southeastward across Idaho and northern Utah, while
another less organized disturbance is seen moving southeastward
off the coast of northern California. The system to our north will
have no impact on our region as we remain under a dry westerly
flow today and highs once again mainly top out in the mid 90s
across the lower deserts.

By Friday, the disturbance off the coast of California is forecast
to strengthen slightly as it comes ashore across southern
California in the afternoon before moving through Arizona Friday
night. The main impact with Friday`s weather system will be the
increase in winds across the region with afternoon and evening
winds commonly gusting to between 20-25 mph across southern
Arizona to as high as 30-40 mph across portions of southeast
California. Heights aloft are also expected to drop enough with
the passage of the dry weather system to bring a noticeable drop
in temperatures as highs on Saturday are expected to mostly top
out in the upper 80s to around 90 degrees, or 6-8 degrees below
normal.

The larger scale pattern is then forecast to shift later over the
weekend into early next week with a ridge building over the
Western U.S. This should quickly boost H5 heights from around
574-578dm on Saturday to around 584dm Monday before peaking at
around 586dm during the middle part of next week. Dry conditions
will persist as the upper level ridge dominates across the region
during at least the first half of next week, while a weaker
gradient should keep winds from being very breezy. Lower desert
high temperatures will quickly rise to a few degrees above normal
starting Memorial Day to as warm as 102-106 degrees by around next
Tuesday and/or Wednesday. With normal highs still rising fairly
quickly during the last week of May, even highs of around 105
degrees would only be 5-7 degrees above normal.

&&

.AVIATION...Updated at 0523Z.

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

Weak upper level troughing over the Desert Southwest will maintain
dry southwesterly flow aloft. In the lower troposphere and the
surface, familiar diurnal patterns continue with the downvalley
patterns underway early in the TAF period (gustiness at KIPL).
This will be followed by upvalley patterns (favoring SW/Wly
directions over Greater Phoenix) and breeziness (gusts to 20kts)
in the afternoon and early evening (gusts 25-30kts at KIPL and
KBLH). Expect clear skies apart from some very minor cirrus
Thursday evening.

&&

.FIRE WEATHER...
Dry and tranquil conditions will continue through the next few
days, with temperatures hovering right around normal for this time
of year. Winds will follow typical diurnal trends with occasional
afternoon gusts around 20 mph today before increasing on Friday
with gusts commonly reaching 25 mph over the eastern districts to
up to 35 mph across southeast CA. MinRH values will range between
8-15% through Friday before improving to 10-20% Saturday, while
MaxRHs improve from 25-40% today to 35-50% by Saturday. High
pressure is then expected to impact the region Sunday through the
first half of next week bringing strong warming and above normal
temperatures, while MinRHs drop back into the single digits.
Overall light winds are also expected starting Sunday.

&&

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

$$

DISCUSSION...Kuhlman
AVIATION...AJ
FIRE WEATHER...Kuhlman