000
FXUS66 KSTO 230850
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
150 AM PDT Tue Apr 23 2024

.Synopsis...
Cooler thru mid-week along with a chance for afternoon showers
and thunderstorms over the mountains. Precipitation chances
increase Thursday into Friday as a weather system moves through,
best chances in the foothills and mountains.

&&

.Discussion...
A robust Delta Breeze is under way as the strong upper ridge of
the past several days has weakened and begun to shift east.
Stratus surged north along the coast on Monday and profiler data
indicate the marine layer has deepened to around 3k ft or deeper.
Surface pressure gradient has reversed from offshore to onshore
and southwesterly gusts of 25-35 mph are common from the
Sacramento area into the Delta.

Mid-level moisture and instability has begun to get drawn
northward ahead of the offshore trough. Forecast soundings
indicate some elevated instability over the region this morning
with the moisture increase, but the question is whether lift will
be sufficient to pop some showers. Recent satellite imagery shows
some mid clouds beginning to develop, and even some virga from
these may be enough to seed some drizzle or light rain as marine
stratus spreads inland this morning.

Otherwise, in addition to the significantly cooler temperatures,
we`re looking at mainly diurnal mountain showers and thunderstorms
later today and Wednesday as the initial trough and closed low
pass mainly to the south of us into SoCal.

Behind that system, a couple stronger short-wave troughs are
forecast to drop into NorCal later in the week reinforcing the
cool and unsettled pattern and bringing a better chance for
showers later Thursday into Friday. QPF is expected to be less
than 0.10" in the valley with around 0.50" over the mountains.
Snow levels will be around 7k ft or so with light snowfall
accumulations possible over the higher peaks. Impacts to travel
are expected to be minimal.

&&

.EXTENDED DISCUSSION (Saturday THROUGH Tuesday)...
Saturday morning, the low pressure system that brought light snow
and showers to the area late in the week moves south and east out
of the Great Basin. Some lingering showers may impact areas in
the foothills and mountains, though most precipitation will occur
on Friday. A brief, broad and flat ridge will then move over the
area, increasing the high temperatures on Saturday and Sunday
afternoons. A developing low over the Pacific Northwest will keep
temperatures from climbing any further on Monday and Tuesday
though, with area high temperatures expected to remain near
seasonable levels all four days. Valley high temperatures will
reach around the low to mid 70s during this time, with foothill
temperatures ranging from the mid 60s to low 70s, and the
mountains from the 50s to 60s. Overall, conditions will be mild
and dry throughout the extended forecast period.

&&

.AVIATION...
Areas of MVFR ceilings with drizzle expected to develop over the
southern half of the Sacramento Valley early this morning and
continue until about 18Z, otherwise mainly VFR conditions next 24
hours. Scattered thunderstorms develop over the mountains after
20Z with local MVFR conditions in the vicinity. Areas of
southwesterly surface wind gusts 25-35 kts west Delta, and local
southerly gusts 15-25 kts in the southern Sacramento Valley next
24 hours. Lighter winds elsewhere.

&&

.STO WATCHES/WARNINGS/ADVISORIES...None.

&&

$$