452
FXUS65 KPSR 082055
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
155 PM MST Sat Jun 8 2024

.SYNOPSIS...
Slightly cooler, although above normal, temperatures are forecast
through the weekend into Monday. Expect temperatures to heat up
by the middle of next week due in large part to high pressure
building into the region. Dry conditions will prevail through the
forecast period.

&&

.DISCUSSION...
For the short term, weak circulation associated with a very weak
upper-level low located over the Sonoran Desert region of the northwest
corner of Mexico continues to gradually move northward into AZ
helping to slightly lower 500 mb heights dropping temps a couple
of degrees. Expect low temperatures this evening to dip to the low
80s for the Phoenix Metro and low to mid 70s for the surrounding
region. Expect low temps to fall to the upper 60s in higher
mountain elevations. Along with the cooler temperatures, the weak
upper-level low will also help enhance somewhat the early evening
breeziness across the area, with the potential for some gusts
exceeding 30 mph at times across portions of western Imperial
County. Upper level clouds will continue to build into the eastern
portions of the CWA this evening, slightly clearing overnight,
building back in tomorrow during the day. Winds will continue to
generally favor diurnal tendencies with occasional afternoon gusts
of 20-25 mph expected across most of the region tomorrow.

Heading into next week, model guidance continues to remain in
pretty good agreement in the overall synoptic pattern as another
upper-level low is set to cutoff off the coast of southern
CA/northern Baja by Monday with a ridge strengthening across the
southwestern CONUS. There still continues to be some discrepancies
examining the ensemble cluster analysis in the overall
positioning/strength of the cutoff low, which will dictate the
positioning of the ridge downstream. Latest trend indicates a
pretty robust ridge building across NM/AZ by midweek with 500 mb
height fields rising above 590dm across most of the region with
values as high as 594-597dm across the eastern half of AZ through
NM. Therefore, an uptick in temperatures can be expected heading
into the Tuesday-Thursday timeframe with another round of
excessive heat conditions possible, especially across the south-
central AZ lower deserts, as highs will likely once again reach
110+ degrees and potentially necessitating the issuance of new
excessive heat products.

Ensemble and cluster analysis shows a cutoff low eventually
making its way through the region by the end of next week,
bringing slightly cooler temperatures. Heading into next weekend,
a more potent large-scale trough will approach the Pacific
Northwest and traverse the western CONUS. However, there is a
large degree of spread amongst the ensembles and large
uncertainty in cluster analysis on the overall depth and position
of the trough, which will dictate whether or not the Desert
Southwest will see any impacts in the form increased winds,
further cooling, and potential precipitation.

&&

.AVIATION...Updated at 1800Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT;
No major aviation weather concerns will exist through the TAF
period under FEW-SCT and at times BKN clouds aoa 20 kft. Wind
directions will favor typical diurnal tendencies. A southerly
cross runway component is expected to prevail for KPHX and KDVT
with speeds mostly aob 8 kt sustained until SW winds definitively
establish this afternoon between 20-22Z. Late afternoon gusts into
the upper teens will be common across all terminals. Hi-Res
guidance continues to show the potential for some weak
reflectivity signatures (high-based scattered virga showers) over
South-Central AZ this evening, mainly to the east, but confidence
is very low in this leading to any aviation impacts.

Southeast California/Southwest Arizona including KIPL and KBLH:
No major aviation weather concerns will exist through the next 24
hours under FEW-SCT high clouds. Winds will favor S to SSW at
KBLH through the period with afternoon and early evening gusts
upwards of 20 to 25 kt. Directions will favor WSW at KIPL by this
afternoon, with gusts to around 25 kt and occasionally up to 30 kt
this evening, before calming overnight and returning to SE early
tomorrow morning.

&&

.FIRE WEATHER...
Hot and seasonably dry conditions will continue to support a high
fire danger across the area into late next week. Slightly cooler
temperatures, although still remaining above normal, can be
expected through Sunday before heating up once again heading into
the middle of next week. Winds will continue to generally favor
diurnal tendencies with occasional afternoon breeziness of 20-25
mph expected across most of the region. MinRHs ranging between
5-15% with poor to fair overnight recoveries of between 20-45%
will be common.

&&

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

$$

DISCUSSION...95/Lojero
AVIATION...Whittock
FIRE WEATHER...95/Lojero