209
FXUS65 KPSR 071141
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
441 AM MST Sun Jul 7 2024

.UPDATE...Updated Aviation Discussion.

&&

.SYNOPSIS...
Extreme heat will continue across the region through the majority of
this week as a strong high pressure remains overhead. Lower deserts
will continue to see afternoon high temperatures in the 110-120
degree range with little to no overnight relief with overnight
low temperatures ranging from the low 80s to low 90s. Some
moisture will start to move back into the region by the middle to
end of this week, leading to an increase in thunderstorm chances
for southeastern Arizona and the Arizona high terrain.

&&

.DISCUSSION...
Upon analysis of upper- and mid-level water vapor satellite imagery
this morning, the strong high pressure system is currently centered
over California and western/southwestern Nevada. This high
pressure system will slowly make its way eastward over the next
week, however it`s strength will largely remain unchanged with 500
mb height fields expected to range between 594-597dm. This will
result in relatively clear skies, with near zero storm activity
for most of our region through the majority of this week. With the
slow eastward propagation and very minimal change in the strength
of the high pressure system, the extreme heat will continue
through much, if not all, of this week. The lower deserts will see
afternoon high temperatures in the 110-120 range with
overnight/early morning low temperatures ranging from the low 80s
to low 90s through at least Thursday. These temperatures will
result in widespread Major HeatRisk and localized Extreme HeatRisk
across the Arizona lower deserts and southeastern California. Due
to this the Excessive Heat Warning has been extended through 8 PM
MST/PDT Thursday, July 11. It is crucial to stay proactive in
protecting yourself from these extreme temperatures as they can
become deadly! Remember to stay hydrated; wear light, loose
fitting clothes; and try to limit your time outdoors, especially
during the hottest part of the day.

The center of the high pressure system will move into western
Arizona by the middle of this week. This will promote some moisture
return into southern and eastern portions of Arizona, leading to
afternoon and early evening isolated shower and storm chances across
southeastern Arizona and higher terrain locations in eastern
Arizona. Global ensembles continue to show PWAT values near 1"
returning to portions of the Arizona lower deserts by Friday at the
earliest. The increase in moisture will cause a slight cool down in
temperatures over the Arizona lower deserts. There is still some
uncertainty in the exact timing of the northward and westward extent
of this increase in moisture. Due to this the Excessive Heat Warning
may need to be extended through Friday, particularly for portions
of southeastern California.

By this coming weekend the high pressure system will make its way to
the Four Corners Region. This will promote better moisture advection
into our region, with global ensemble models showing PWATs rising
above 1" across the region this coming weekend. This will lead to
increased shower and storm chances, at least for the Arizona
lower deserts. With the increased moisture, temperatures will also
trend down below the excessive heat threshold.

&&

.AVIATION...Updated at 1140Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
Confidence in a full easterly wind shift at all TAF sites is low
this morning, as a light west or light variability may prevail
between 12-17Z at all but KIWA. SW to W winds will then increase
by 17-18Z, with speeds up to 10-14 kts and gusting up to 20-25 kts
this afternoon. More typical diurnal trends are expected tonight,
with light winds becoming variable or east by or just after
midnight. SKC will prevail.

Southeast California/Southwest Arizona including KIPL and KBLH:
Wind directions will generally favor SE at KIPL, aside from a few
hour period of W this evening. S`rly directions will prevail at
KBLH. Speeds will remain mostly aob 12 kt at KIPL. Speeds will be
slightly stronger at KBLH, with sustained speeds in the low teens
and the potential for some occasional gusts up to 20-25 kt. SKC
will prevail.

&&

.FIRE WEATHER...
Hot and dry conditions continue through most of next week as high
pressure remains overhead. Extreme temperatures continue with daily
high temperatures generally between 110-120 degrees across the lower
deserts and 95-110 degrees across the higher terrain. Daily MinRH
values will range from 5-15% across the lower deserts and 10-20%
across the Arizona higher terrain, with overnight recoveries
generally in the 30-50% range. Winds will be fairly light and tend
to follow their typical diurnal patterns, with some occasional
gusts near 20 mph in the afternoons. This afternoon looks to be
the breeziest this week, with afternoon wind gusts up around 20-30
mph, mainly across the eastern districts. The very hot and dry
conditions will lead to an increased fire danger threat.

&&

.CLIMATE...

Record Highs

           Phoenix      Yuma      El Centro
          ---------    -------   -----------
July 7    118 (2017)  118 (2017)  121 (2017)
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 Thursday for AZZ530>555-
     559.

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

&&

$$

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