712
FXUS65 KPSR 081930
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1230 PM MST Mon Jul 8 2024

.SYNOPSIS...
Extreme heat will continue to prevail across the region
throughout the work week as high temperatures across the lower
deserts are expected to range between 112-122 degrees. Some
moisture will start to move back in starting on Tuesday, providing
isolated t-storm chances for southeastern AZ and the Arizona high
terrain. The chances for more widespread thunderstorm activity
increases by next weekend.

&&

.DISCUSSION...
The latest water vapor satellite imagery shows very dry air
encompassing most of the western third of CONUS as a result of an
expansive ridge of high pressure that has been sitting near CA since
late last week and will slowly shift eastward as the week
progresses. The current positioning of this ridge continues to
provide a northerly wind flow, which is keeping very dry air
entrenched across the region with near zero storm activity. This
will continue to be the case through today, where most of AZ is
likely to be convection free once again. The main weather concern
as a result of this high pressure continues to be the extreme heat
as the mostly clear skies and the enhanced 500 mb height fields
ranging between 594-597dm will continue to support high
temperatures across most of the lower desert communities to top
out between 112-122 degrees, with the highest readings across the
western deserts. These temperatures will be high enough for
multiple areas to either tie or break record highs. Widespread
major to locally extreme HeatRisk will continue through the end of
the work week and as a result the Excessive Heat Warning has now
been extended through Friday. Therefore, if partaking in outdoor
activities it is very crucial to take all the necessary heat
precautions to avoid any heat-related illnesses.

Heading through the middle and latter half of the week, the ridge of
high pressure is expected to shift into northwest AZ. The flow
pattern will be more favorable for some moisture intrusion into the
region, enough to spark isolated thunderstorm activity across
portions of southeastern AZ as well as across the AZ high terrain
such as the White Mountains and Mogollon Rim. The overall
isolated coverage will likely continue through the end of the week
with the lower deserts expected to remain dry and thus any
associated cloud cover/outflow boundaries emanating from the
convective activity will likely not have any effect on the
temperatures across the lower deserts. This is the reason why
confidence continues to remain high enough for the extreme heat to
continue right through the end of the work week.

Heading into next weekend, the ensembles continue to remain in very
good agreement that the high center will shift into the Four Corners
Region. Thus, the flow pattern will shift more from the east to
southeast, which will advect some deeper moisture into the region
with ensemble mean PWATs rising to as high as 1.2-1.5". Therefore,
conditions are going to become more favorable for more widespread
thunderstorm activity to materialize, including for the lower
deserts. Given the increasing moisture and convective coverage,
temperatures luckily are expected to cool off as well below the
excessive heat threshold.

&&

.AVIATION...Updated at 1745Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation weather concerns will exist through the TAF period
under clear skies. Satellite imagery does indicate some wildfire
smoke aloft, however this smoke should remain diffuse enough to
not cause any issues with slantwise visibility. Winds will follow
typical diurnal trends with an hr or two of variability expected
at KPHX before winds go westerly. Afternoon gusts up to around 20
kts will be common through sunset. Winds will shift back around to
the E-SE by 08Z-09Z tonight.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation weather concerns are expected through the next 24
hours under clear skies. Winds will favor southeasterly at KIPL
through this afternoon before becoming WSW by sunset. There is a
potential to see some gusts up to 20-25 kts at KIPL this evening,
otherwise speeds will remain around 10 kts or less. Winds will
continue out of the S-SW at KBLH with gusts increasing to around
18-20 kts this afternoon.

&&

.FIRE WEATHER...
Well above normal temperatures and dry conditions will continue
through the majority of this week. Daily afternoon high temperatures
will generally be in the 112-122 degree range across the lower
deserts and in the 95-110 degree range across the higher terrain.
MinRH values will range from 5-15% across the lower deserts and 10-
20% in the higher terrain, with overnight recoveries generally in the
30-50% range, through Friday. Winds will be fairly light and tend to
follow their typical diurnal patterns, with some occasional
afternoon gusts up around 20 mph. Limited moisture will start to
creep back into the region for the latter half of the work week,
leading to a slight chance for isolated thunderstorms in the higher
terrain. The very hot and dry conditions will lead to an increased
fire danger threat.

&&

.CLIMATE...

Record Highs

           Phoenix      Yuma      El Centro
          ---------    -------   -----------
July 8    115 (1985)  118 (1958)  117 (1942)
July 9    116 (1958)  119 (1958)  117 (1958)
July 10   115 (1958)  118 (1959)  116 (2021)
July 11   118 (1958)  118 (1958)  117 (1975)

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...Excessive Heat Warning until 8 PM MST Friday for AZZ530>555-559.

CA...Excessive Heat Warning until 8 PM PDT Friday for CAZ560>570.

&&

$$

DISCUSSION...Lojero
AVIATION...Salerno
FIRE WEATHER...Berislavich
CLIMATE...Berislavich/Kuhlman