509
FXUS65 KPSR 200545
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1045 PM MST Sun May 19 2024

.UPDATE...Updated 06z Aviation Discussion.

&&

.SYNOPSIS...
Temperatures this week will be near normal as a couple weather
systems pass through the region, but mainly to the north of our
area. These systems will lead to breezy to windy conditions during
the afternoon and evening hours, with the highest winds and greatest
impacts expected on Monday. There is a slight chance for some virga
and/or sprinkles in south-central AZ tomorrow afternoon, otherwise
dry conditions continue into next week.

&&

.DISCUSSION...
Analysis of upper-level water vapor imagery this afternoon reveals a
closed low off the coast of southern California along with a trough
digging to the southeast in the Pacific NW. Ahead of these systems,
wind gusts this afternoon and early evening are expected to easily
reach into the mid 20s areawide to 30-35 mph across portions of
southeast California. These winds combined with low humidity will
lead to elevated to critical fire weather conditions today. The
aforementioned closed low will move on shore during the overnight
hours and get swept up in the aforementioned trough as it
continues to dig to the SE. This system will bring a cold front to
the area tomorrow, knocking afternoon temperatures down to near
normal (about 5 degrees cooler than today`s forecasted high
temperatures). Moisture will be limited, but some virga and/or
sprinkles will be possible in south-central Arizona during the
early afternoon as the cold front moves through. Winds will be the
main concern tomorrow afternoon and early evening and will likely
reach 25-35 mph across south-central Arizona and 30-45 mph across
southeast California and the Lower CO River Valley. Winds may
briefly gust up around 40 mph in south-central AZ along the front
as it moves through in the early afternoon. These winds combined
with the low humidity will lead to another day of elevated to
critical fire weather conditions.

Broad troughing over Western CONUS will persist through next weekend
along with a few shortwaves sliding to our north throughout the
week. This will help keep temperatures right around or even slightly
below normal heading into Memorial Day Weekend. Aside from the
slight chance of some virga and/or sprinkles tomorrow afternoon, dry
conditions will continue through next weekend. Global ensemble
models are in fairly good agreement that heights aloft will return
to zonal flow and then start to rise early next week. This will
allow for another warming trend and push temperatures back above
normal.

&&

.AVIATION...Updated at 0545Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Wind directions will follow their typical diurnal tendencies
through at least early tomorrow morning. The typical SE switch is
expected to take hold by 08-10Z at KPHX, KIWA, and KDVT.
Overnight, mid and high level clouds will begin to fill in over
the region, with bases reaching their lowest midday tomorrow at
around 12 kft. Late tomorrow morning, winds will switch out of the
SW sooner than usual before increasing and developing gusts into
the mid 20s by the afternoon. Confidence is good in virga showers
passing over the terminals during the early afternoon (coinciding
with the lowest cloud bases) ahead of a front. Anticipate the
front to sweep over the terminals sometime between 20-23Z and
temporarily bring gusts upwards of 30-35 kt. Skies will clear
rather rapidly late afternoon following frontal passage.

Southeast California/Southwest Arizona including KIPL and KBLH:
The primary aviation weather concern through the next 24 hours
will be gusty SW to W winds. Directions will favor W at KIPL and S
to SW at KBLH through the period, with lower speeds overnight and gusts
picking up again tomorrow morning. Gusts will peak tomorrow
afternoon between 30-35 kt at both terminals, and with the
stronger winds, reductions in visibility from lofted dust will be
possible. Expect FEW-SCT and at times BKN clouds mostly aoa 20 kft
overnight into tomorrow morning.

&&

.FIRE WEATHER...
A cold front will move through the region tomorrow knocking
temperatures down to near or slightly below normal along with
brining strong, gusty winds to the region. While some
virga/sprinkles will be possible in south-central Arizona, there
is no chance for wetting rain with this cold front. Throughout the
week, MinRH will be in the single digits for lower elevations and
in the teens across the higher terrain. Overnight recoveries will
be poor to fair and in the 20-40% range. Wind speeds will be the
highest on Monday with widespread gusts as high as 30-35 mph. This
combined with the low RH and dry fine fuels will lead to near
critical thresholds. Land managers should be cautious for rapid,
uncontrolled spread of any ongoing fires or new starts Monday. For
the remainder of the week, afternoon gusts will be in the 20-25
mph range, which will lead to slightly elevated fire danger.

&&

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

$$

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