617
FXUS65 KPSR 081759
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1059 AM MST Sat Jun 8 2024

.UPDATE...Updated 18z Aviation Discussion.

&&

.SYNOPSIS...
Cooler temperatures are expected through the weekend as
a weak disturbance moves across region. Temperatures then heat up
once again heading into the middle of next week as high pressure
builds over the region. Seasonably dry conditions will prevail
through the next 7 days.

&&

.DISCUSSION...
The latest water vapor satellite imagery depicts a weak circulation
over the central Baja Peninsula associated with a very weak upper-
level low that has been spinning over this general region during the
past couple of days. This weak low will gradually move northward
across AZ through the weekend helping to slightly lower the 500 mb
heights to 585-588dm. As a result, temperatures will cool slightly
from what they were the past couple of days. High temperatures today
will generally range between 105-110 degrees and cool even further
Sunday-Monday into the low to mid 100s across the lower deserts. The
overall HeatRisk will remain moderate across most of the region
through the weekend and as a result, if planning outdoor
activities, the necessary heat precaution measures should still be
performed. Along with the cooler temperatures, the weak upper-
level low will also help enhance somewhat the afternoon and early
evening breeziness across the area, with the potential for some
gusts exceeding 30 mph at times across portions of western
Imperial County due to mountain rotors.

Heading into next week, the 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 becoming more likely, 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.

The ensembles show the cutoff low eventually making its way through
the region by the end of the 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 on the overall depth of the trough, which will
dictate whether or not the Desert Southwest sees some sort of
impacts in the form increased winds and further cooling.

&&

.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 during the next several days.
Slightly cooler temperatures, although still remaining above
normal, can be expected through the weekend 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 20-40% will be common.

&&

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

$$

DISCUSSION...Lojero
AVIATION...Whittock
FIRE WEATHER...Lojero