Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 242158
Area Forecast Discussion
National Weather Service Sacramento CA
258 PM PDT Fri Mar 24 2017
Storm systems are expected today, Sunday into Monday, with
possibly a third system toward the middle of next week.
A closed upper low is currently situated off the British Columbia
coast, with associated frontal system now pushing into Northern
California. Light to locally moderate precipitation is moving
through the region, with reports of snow levels down to ~2500
feet along Interstate 5, and 4000-5000 feet along the Sierra.
The band of heaviest precipitation has pushed eastward into the
Sierra, though periods of showers are likely to continue across
the region tonight. Short range models are also hinting at the
Shasta County convergence line of thunderstorms forming for a few
hours this evening as well.
Currently expect snow totals of up to a foot across much of the
Sierra, and orographically favored regions up to 18 inches. Given
the usually higher traffic across the mountains on Friday,
lengthy traffic delays are likely across the Sierra.
A few showers may linger across the region on Saturday, but much
of the region is expected to remain dry. A fast moving shortwave
ridge passes through the region Saturday night.
The next storm system then arrives on Sunday. That system looks to
be a bit weaker than the current one, with mainly light
precipitation across the Valley, and light to moderate totals over
the Sierra. Given the timing of the system, and heavy mountain
traffic on Sundays, another period of lengthy traffic delays will
be possible across the Sierra.
.EXTENDED DISCUSSION (Tuesday THROUGH Friday)
Dry weather returns Tuesday as ridging briefly builds in over
NorCal. Some breezy northerly winds possible with warming
temperatures. Models have come into better agreement with next
system for mid-week. 12z runs show more of an inside slider system
will main low dropping SE from Pac NW into the four corners
region by late Thursday. This lends confidence toward a drier
forecast for most of the area with a chance for showers mainly
across the northern mountains and the Sierra. QPF amounts don`t
look overly impressive with snow levels near pass levels. Pattern
would also bring breezy to windy northerly winds across the area
depending on the exact track of the low.
Storm system continues to shift east across the area this
afternoon. MVFR to VFR conditions for TAF sites. Precip will
taper off through the evening hours with improving flight
conditions. Winds gradually decreasing through the afternoon hours
and will be under 10 kts tonight and Saturday.
Winter Storm Warning until 5 AM PDT Saturday for West Slope
Northern Sierra Nevada-Western Plumas County/Lassen Park.
Winter Storm Warning until 5 AM PDT Saturday for Shasta Lake
Area / Northern Shasta County.