142
FXUS65 KPSR 130952
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
252 AM MST Tue Aug 13 2024

.SYNOPSIS...
Thunderstorm chances this afternoon and evening will be confined to
the higher terrain locations in eastern Arizona. Drier air arrives
for the latter half of the work week causing little to no monsoonal
activity, even over the higher terrain areas. Slight uptick in
moisture this weekend will lead to a slight increase in
thunderstorm activity, mainly confined to the Arizona higher
terrain. Temperatures will remain largely unchanged through the
weekend and run near to slightly above normal.

&&

.DISCUSSION...
Analysis of upper-level water vapor imagery this morning shows the
subtropical high pressure system centered over Texas stretching back
into New Mexico. There is also an upper-level trough moving onto the
coast of the Pacific northwest. Over the next few days as this
trough moves further inland it will flatten out the subtropical
high, which will lead to westerly flow aloft bringing much drier air
into the region. Mid-level water vapor imagery shows this much drier
air already in eastern portions of CA and NV and starting to move
into far western portions of AZ. Current PWAT values of 1.0-1.5"
across the region will decrease slightly by this afternoon and
evening, but there will still be enough moisture to support the
development of isolated to scattered showers and storms across the
higher terrain areas in eastern AZ.

For the middle and end of the workweek, PWAT values will lower to
the 0.8-1.2" range across the region, which is unfavorable for
thunderstorm development. Global ensembles now show a secondary
upper level low pressure system digging into the Pacific
northwest on Thursday and Friday, which will delay the subtropical
ridge from building back into our region. NBM PoPs are now around
5% or less across the entire CWA for Wednesday-Friday.

This weekend, as the aforementioned trough continues to dig off
the coast of the Pacific northwest, the subtropical ridge will
start to strengthen across NM/TX. This will result in a return of
southerly/southeasterly flow to the region and cause a slight
increase in moisture. In turn, daily storm chances return this
weekend and continue into the beginning of next week, with most,
if not all, activity confined to the higher elevation locations.

Temperatures will remain largely unchanged through the weekend.
Afternoon high temperatures will be in the 100-110 degree range
across the lower deserts and in the 90-100 degree range in the
higher terrain areas. Temperatures will be near to slightly above
normal, with HeatRisk in the Minor to Moderate range across the
region.

&&

.AVIATION...Updated at 0515Z.

South Central Arizona including KPHX, KIWA, KSDL, and KDVT:
No aviation concerns are expected during the next TAF period.
Winds will follow typical diurnal trends, with occasional gusts
during the afternoon hours near 15-20 kts. Shower and thunderstorm
activity will once again initiate over the usual areas tomorrow
afternoon but chances of in the vicinity of the terminals during
that timeframe is less than 5%. Chances of distant outflows
impacting the terminals are also minimal (~10%). SCT mid and high
level clouds will diminish in coverage overnight, with just a FEW
low-level clouds prevailing through the remainder of the period.

Southeast California/Southwest Arizona including KIPL and KBLH:
No aviation concerns are expected during the TAF period. Winds
will follow familiar diurnal trends, with occasional gusts near 20
kts during the afternoon and evening hours. Mostly clear skies
will prevail during the next 24 hours.

&&

.FIRE WEATHER...
Shower and thunderstorms chances this afternoon and evening will
be confined to the higher terrain areas across eastern AZ. With
any thunderstorm activity, there will be strong winds along with
the potential for gusty outflows that can cause sudden wind
shifts. Thunderstorms will also contain localized heavy downpours
and frequent lightning. Drier air will move into the region for
the later half of the week with little to no thunderstorm
activity expected. Aside from thunderstorm winds, the winds will
tend to follow their typical diurnal tendencies with some
afternoon upslope breeziness near 20 mph. MinRH values today will
be in the 20-30% range across the AZ districts and in the
10-20% range across the CA districts. For the remainder of the
workweek, minRH values will be in the 10-25% range across all
districts. Overnight recoveries will be in the 30-50% range.
Temperatures though the week will remain largely unchanged and run
near to slightly above normal.

&&

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

$$

DISCUSSION...Berislavich
AVIATION...RW
FIRE WEATHER...Berislavich