437
FXUS65 KPSR 051938
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
1238 PM MST Fri Jul 5 2024

.SYNOPSIS...
Strong high pressure over the region will result in
excessive heat conditions and mainly dry conditions through at
least the first half of next week and possibly longer. Most of the
lower desert locations are expected to see daily highs
approach or even exceed 115 degrees. Some moisture return will
bring increased thunderstorm chances back to the Arizona high
terrain by the middle of next week.

&&

.DISCUSSION...
A strong ridge of high pressure is currently centered just off the
northern CA coastline with a northerly flow encompassing the region.
500 mb height fields through the weekend and heading into all of
next week will generally range between 594-597dm with a slow drift
of the ridge towards Great Basin and Desert Southwest heading into
the middle of next week. The northerly flow will continue to advect
dry air into the region with PWAT values this weekend falling to as
a low 0.6-0.7". Thus the dry air along with the subsidence from the
high pressure will result in mostly clear skies and consequently
hinder thunderstorm activity through at least the first half of next
week. The combination of the enhanced 500 mb heights and the mostly
clear skies will result in a several day stretch of extreme heat
conditions, which will likely carryover through most if not all of
next week.

Lower desert high temperatures are expected to range between 112-120
degrees, with the highest readings expected across the western
deserts with very little overnight relief as lows are expected to
range between lower 80s to lower 90s. Multiple daily record high and
warm low temperatures may be tied or broken. The extreme
temperatures will lead to widespread major to locally extreme
HeatRisk to materialize and thus Excessive Heat Warnings remain in
effect through at least Tuesday. It is probable that the warning
will need to be extended through the latter half of next week
given that the forecast high temperatures will likely remain
steady state. Given the prolonged nature of this extreme heat
episode, it is crucial that people take all the necessary heat
precautions such frequently hydrating, wear light-loose fit
clothing, seek frequent breaks in the shade, and avoid strenuous
outdoor activities during the hottest part of the day. Remember,
heat is the number one weather-related killer in the country!

As the center of the high pressure gradually shifts eastward into
northern AZ and southern UT by the middle to latter half of next
week, moisture levels will improve just enough that storm chances
will increase across the higher terrain areas of eastern AZ
towards portions of southeast AZ as well as the White Mountains
and Mogollon Rim. However, across the south-central AZ lower
deserts it will likely still remain mostly dry, which is why there
is a good potential for the excessive heat conditions to continue
through the end of next week. It looks like once the center of
the high moves over the Four Corners Region by next weekend, a
deeper push of monsoonal moisture will move in, which will help
with increasing storm chances across the lower deserts as well as
result in cooler temperatures.

&&

.AVIATION...Updated at 1730Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation concerns are expected during the TAF period. Winds
will follow typical diurnal trends, with occasional gusts this
afternoon in the mid-teens, upwards of 20 kts. Other than a FEW
mid-level clouds popping up over high-terrain areas, skies should
be mostly clear through Saturday morning.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected during the TAF period. Winds at
IPL will favor an E`rly component, with extended periods of
variability through this evening. Winds may briefly try to switch
out of the SW early tonight, but confidence in that shift is low
at this time. At BLH, winds will favor a E/NE direction during the
afternoon, before more diurnal trends take over by the evening
hours. Mostly clear skies are expected through Saturday morning.

&&

.FIRE WEATHER...
Hot and mainly dry conditions will prevail across the area
through the weekend and into the first half of next week as
strong high pressure settles in from the northwest. Excessively
hot temperatures with highs generally between 112-120 degrees are
expected across the lower deserts each day through at least early
next week. Daily MinRH values through early next week will fall
between 5-15% across the lower deserts, while higher terrain areas
in Arizona will mostly see 10-20%. Winds will be fairly light and
follow diurnal trends, occasionally gusting to 20 mph during the
afternoon hours. The combination of the very hot and dry
conditions will lead to an increased fire danger threat.

&&

.CLIMATE...

Record Highs

           Phoenix      Yuma      El Centro
          ---------    -------   -----------
July 5    116 (1983)  116 (1905)  115 (2007)
July 6    116 (1942)  117 (2018)  118 (1966)
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)

&&

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

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

&&

$$

DISCUSSION...Lojero
AVIATION...RW
FIRE WEATHER...Benedict/Lojero
CLIMATE...Kuhlman