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000
FXUS65 KPSR 201110
AFDPSR

Area Forecast Discussion
National Weather Service Phoenix AZ
410 AM MST Sat Apr 20 2024

.Update...12Z Aviation Discussion

&&

.SYNOPSIS...
Unseasonably warm temperatures and mostly sunny skies will
persist through early next week. Daily high temperatures, mostly
in the mid nineties to as hot as the upper nineties are expected
across the lower deserts, with the hottest days on Sunday and
Monday. This will lead to widespread minor heat-related health
risks. A slow moving weather system later next week is forecast
to bring a gradual cooling trend through the end of the week,
while also increasing winds across the region.

&&

.DISCUSSION...
A weak upper level shortwave continues to track eastward across
the Desert Southwest with the core of the disturbance bringing
some high based virga showers to portions of central and eastern
Arizona. By sunrise or shortly after sunrise, this activity will
exit into New Mexico leaving behind clear skies for the rest of
today. From tonight through Monday, the region will then fall
under a slow moving shortwave ridge which will boost H5 heights
back to around 580dm, while also boosting daytime highs into the
mid to upper 90s for Sunday and Monday. Both of these days will
bring the hottest temperatures the region has seen so far this
spring with localized Moderate HeatRisk possible from Phoenix
through southeast California. NBM probabilities of reaching 100
degrees largely remains unchanged at 5-20% affecting portions of
Phoenix, Lower CO River Valley, and western Imperial Co.

By early next week, a Pacific upper level trough will start to
approach the West Coast, but it is likely to stall out some by
Tuesday as it becomes closed off. Over the past 24 hours,
ensemble guidance has slowed up the initial push of the trough
into our region with it mainly holding off until late Wednesday
into Thursday. However, as the trough approaches the California
coast by Tuesday, it should knock down our heights aloft over our
region allowing for the beginning of a cooling trend. Forecast
highs do drop back into the low to mid 90s on Tuesday and
Wednesday before the bigger drop in temperatures is likely on
Thursday once the trough eventually swings through our region. The
influence of the incoming trough by the middle of next week will
also bring an increase in winds over the area with afternoon wind
gusts likely reaching to between 20-30 mph for several days.

Guidance then suggests a second follow-on shortwave trough will
be possible by around next Friday or Saturday and this could drop
daytime highs down to slightly below normal, or as low as the
lower 80s. The first weather system during the middle of next week
looks completely dry, but there may some slight chances for rain
possible over higher terrain areas with the second system.

&&

.AVIATION...Updated at 1110Z.

South-Central Arizona including KPHX, KIWA, KSDL, and KDVT:

No aviation concerns are expected during the TAF period. Winds
will be light (speeds aob 10 kts) and follow diurnal tendencies.
Other than a FEW high clouds passing over the region later in the
forecast window, skies will be mostly clear.


Southeast California/Southwest Arizona including KIPL and KBLH:

No aviation concerns are expected during the TAF period. Winds
will be light (aob 10 kts) and follow diurnal tendencies. Clear
skies will give way to a FEW to sometimes SCT high clouds by this
evening.

&&

.FIRE WEATHER...
Dry conditions and above normal temperatures will persist through
early next week as lower desert highs top out each day mostly in
the mid 90s. Winds this weekend will overall be light following
diurnal daily trends with any afternoon breeziness in the mid
teens. Min RHs will continue to fall into the 5-15% range each
day, while overnight Max RHs mostly stay in a 25-45% range for
most places. A cooling trend is then forecast for the latter half
of next week eventually bringing temperatures back down to normal
or below normal late next week. Breezy to locally windy
conditions are also expected for much of next week with daily
afternoon gusts commonly reaching to between 20-30 mph. Humidities
are likely to stay quite low next week with daily MinRHs around 10%
through the middle of the week before some improvement is
forecast to around 20-25% late next week as temperatures cool
down.

&&

.PSR WATCHES/WARNINGS/ADVISORIES...
AZ...None.
CA...Wind Advisory until 5 AM PDT early this morning for CAZ562.

&&

$$

DISCUSSION...Kuhlman
AVIATION...RW
FIRE WEATHER...Kuhlman