NWS Area Weather Forecast Discussion
County Warning Area [CWA]: STO Regional NWS Weather Office: Sacramento, CA
FXUS66 KSTO 182228
Area Forecast Discussion
National Weather Service Sacramento CA
328 PM PDT Mon Mar 18 2019
Dry and mild weather into Tuesday. Precipitation chances return
Tuesday night bringing high mountain snow with travel delays
through Wednesday night. Another wet system is possible late
Friday into Saturday.
Dry and mild once again today, with temperatures 1 to 5 degrees
warmer than this time yesterday. The warmest spot is Stockton,
where it was 78 degrees at 3 pm PDT, with 70s across the rest of
the Valley. Today will be the warmest day of the week, with more
clouds and unsettled weather for the rest of the week. Highs are
expected to cool a bit over the Valley on Tuesday as the leading
edge of a Pacific system approaches bringing increasing clouds and
a return to cooler onshore flow.
The system gradually spreads in Tuesday, with precipitation
arriving by evening. A Winter Weather Advisory has been issued for
the northern Sierra from 8 pm PDT Tuesday to 11 pm PDT Wednesday
above 6000 feet due to travel delays and chain controls from snow.
Snow will initially be light and at pass levels (around 7200
feet), then become moderate in heavier convective showers after
midnight, with snow levels dropping to around 5500 feet Wednesday.
Total snow accumulations of 6 to 9 inches, with localized amounts
up to 12 inches are possible.
Valley total rainfall will be around 0.25" to 0.50" through early
Thursday. Wet commutes are expected Wednesday morning and
afternoon and could cause minor delays.
Wednesday afternoon and early evening thunderstorms are possible,
mainly over the northern San Joaquin Valley and through the
Motherlode as the core of the upper low edges northward into the
area. Instability depends to some degree on sunlight from afternoon
A relative break in showers is expected on Thursday under short
wave ridging ahead of a stronger system late in the week. EK
.EXTENDED DISCUSSION (Friday THROUGH Monday)
By Friday morning, the main upper low will be located over the
southwestern US with predominantly dry conditions over northern
California. A trough approaches the area by Friday and and a quick
system looks to bring more rain and mountain snow. Precipitation
amounts have been trending down with this storm only a tenth of an
inch up to a half inch expected for the duration of this system
through Saturday morning. For now, snow amounts may only be a couple
inches with snow levels mainly above 6000 feet. Upper ridging moves
across the area Saturday into Sunday bringing a break in
precipitation before models hint at another system which may impact
the region early next week. Valley high temperatures remain in the
60s Friday through the weekend, with higher elevations in the 40s
Another quiet day with VFR conditions and winds generally below
Winter Weather Advisory from 8 PM Tuesday to 11 PM PDT Wednesday
for West Slope Northern Sierra Nevada.