316
FXUS65 KPSR 012310
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
410 PM MST Sat Jun 1 2024

.UPDATE...
Updated Aviation

&&

.SYNOPSIS...
Seasonably hot and dry weather conditions will persist through early
next week with temperatures running 3 to 5 degrees above normal. By
the middle through latter half of next week, high pressure is
forecast to strengthen across much of the western United States,
resulting in hotter temperatures as highs get closer to 110 degrees
across much of the lower deserts.

&&

.DISCUSSION...
A quasi-zonal flow pattern continues to persist across the Desert
Southwest with subtropical ridging across central Mexico and
troughing across the northern tier of the western United States.
This overall flow pattern will persist through at least Monday with
temperatures remaining steady state with highs topping out between
100-105 degrees across the lower deserts. A very weak shortwave
extending from base of the trough over the Pacific Northwest will
skirt the region through Sunday, however, no discernible sensible
weather impacts are expected from it other than just slightly
enhancing the afternoon and early evening breeziness.

The weather pattern starts to shift heading into the Tuesday-
Wednesday timeframe as an upper-level ridge of high pressure begins
to amplify across much of the western United States. At the same
time, a weak cutoff low will develop and sit just off the central
Baja Peninsula. With the developing ridge, the upper-level height
fields are likely to rise to between 589-593dm, resulting in hotter
temperatures during the middle to latter half of the week.
Temperatures on Wednesday are likely to range between 105-110
degrees across most of the lower desert communities and likely be a
touch warmer on Thursday with highs ranging between 106-111 degrees.
These hotter temperatures will certainly will elevate the HeatRisk
to moderate areawide with areas of major HeatRisk materializing on
Thursday as temperatures approach 110 degrees.

Heading into Friday and next weekend, guidance has come into better
agreement in showing the cutoff low over the Baja Peninsula moving
northward through southern CA/western AZ, which will lower the upper-
level height fields and result in a slight cooling trend with
temperatures closer to 105 degrees. Ensembles also hint that
potentially another larger scale trough from the Pacific may move
into the west coast later next weekend, however, differences are
noted in the overall strength and positioning and thus what impacts
if any it will have in our region is unknown at this time.
With the cutoff low near the Baja Peninsula late next week, the
south to southeast flow on the east side will likely advect some
moisture into AZ with a slight chance of isolated afternoon
convection across the higher terrain areas of eastern AZ.

&&

.AVIATION...Updated at 2310Z.

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

No significant weather issues will exist through Sunday afternoon
under clear skies. Wind trends will again follow a near persistence
forecast around the Phoenix metro, albeit with more frequent
westerly gusts up to 20 kt through early evening. Periods of
variable directions will be common during directional shifts. For SE
California terminals, sundowner gusts at KIPL should be more
pronounced than previous days with occasional daytime gusts around
20 kt at KBLH.

&&

.FIRE WEATHER...
Little to no change in the weather pattern will keep seasonably dry
and hot conditions in place through early next week. Expect lower
desert highs between 100 and 105 degrees, or 3-5 degrees above
average each day. Hotter temperatures are expected by the middle to
latter half of the week as readings close in at 110 degrees. MinRH
values will continue to run between 5-15% across the majority of the
area each day, while overnight recoveries will continue to range
from poor to fair at around 25-40%. Winds will overall be fairly
light following diurnal tendencies with periodic afternoon gusts of
15-20 mph.

&&

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

&&

$$

DISCUSSION...Lojero
AVIATION...18
FIRE WEATHER...Kuhlman/Lojero