NWS Area Weather Forecast Discussion
County Warning Area [CWA]: STO Regional NWS Weather Office: Sacramento, CA
FXUS66 KSTO 211030
Area Forecast Discussion
National Weather Service Sacramento CA
230 AM PST Mon Jan 21 2019
Showers taper off across the region early today with a few
expected to linger into this evening across the higher elevations
of the northern Sierra Nevada. Dry weather will locally breezy
northerly winds expected through the week.
Upper trough shifting east into the Great Basin. Radar shows
numerous showers continuing across the northern Sierra west slopes
with a few lingering showers elsewhere. Current temperatures are
colder compared to 24 hours ago and range from the 20s in the
mountains to the mid and upper 40s across the Central Valley.
Trough continues to shift east the next several days allowing
ridging from the eastern Pacific to shift over NorCal beginning
tonight. Showers will taper off across the northern Sierra today
with perhaps a few lingering along the crest into early this
evening. Elsewhere, clearing skies and northerly winds expected to
develop by this afternoon.
Upper high will build in Tuesday with dry and milder weather.
Northerly flow will continue with some patches of late night and
morning valley fog, mainly along the eastern edge of the valley.
.EXTENDED DISCUSSION (Friday THROUGH Monday)
Quiet weather is expected for the extended part of the forecast
due ti an amplified ridge across the eastern Pacific setting up
shop. Mostly clear skies may lead to early morning fog most
mornings, which will then be followed by warmer than normal high
temperatures each day. Forecast highs for the valley each day will
be in the 60s, with the upper 40s and low 50s being seen at
higher elevations. Low temperatures will generally be around
Satellite imagery this morning shows widespread high cloud over
the region with TAF sites reporting VFR conditions. There is some
clearing along the western side of the CWA, which could lead to
IFR/MVFR conditions later this morning if the winds continue to
weaken. Once the low completely pushes eastward, VFR conditions
are expected during the daytime as high pressure will build over
the region. IFR/MVFR conditions will be possible tomorrow night
due to patchy fog developing.
Winter Storm Warning until 4 AM PST early this morning for West
Slope Northern Sierra Nevada-Western Plumas County/Lassen Park.