Area Forecast Discussion
Issued by NWS Sacramento, CA
FXUS66 KSTO 161133
Area Forecast Discussion
National Weather Service Sacramento CA
333 AM PST Mon Jan 16 2017
Dry through Tuesday, then a series of winter storms will begin
Wednesday and continue into early next week.
Amplified upper air pattern will continue dry weather across
NorCal the next couple of days. Despite some high clouds spilling
over the ridge, fog and stratus has redeveloped through much of
the Central Valley as strong low-level inversions remain in place.
Current temperatures range from the teens and lower 20s in the
colder mountain valleys to the upper 30s and lower 40s in the
thermal belts along the periphery of the valley. Stratus covered
portions of the Central Valley are in the upper 30s and lower 40s,
while elsewhere through the valley readings are in the lower 30s.
Little change is expected today and Tuesday as dry weather
continues as the ridge gradually flattens. The north end of the
Sacramento Valley will continue to see mild temperatures with
light northerly winds while areas from Sacramento southward will
continue to fight the stratus with only a few hours of late-day
sunshine expected leading to daytime highs only around 50.
Over the past 24 hours, models have settled on Wednesday for the
timing of the return of wet weather to NorCal. Wet and windy
conditions will return by Wednesday afternoon and continue into
early Thursday as the digging upper trough interacts with another
plume of deeper moisture over the eastern Pacific. Up to 12 hours
of moderate precipitation can be expected with 1/2 to 1 inch of
rain in the valley and 1-3 inches in the foothills and mountains.
Snow levels with this initial system will generally range from
5000 to 7000 feet Wednesday, then lower quickly to 3500-4500 feet
by early Thursday. A foot or more of snow will be possible for the
mid and upper slopes of the northern Sierra.
Showery weather expected to continue Thursday, then another wet
and windy system moves into the region Thursday night with lower
snow levels (3-4K ft). This will be a fast moving system with QPF
forecast to be a little lighter than the Wednesday one.
Main impacts from these first two storms this week are expected
to be centered around gusty winds and mountain snow. Widespread
flooding is not as likely as last week as snow-levels will be
moderately low and duration of QPF relatively short.
.EXTENDED DISCUSSION (Friday THROUGH Monday)
Pacific frontal system moves through late Thursday through Friday
with rain and mountain snow. Models showing decent precip totals
with this system along strong wind and the potential for some snow
into the foothills Friday night into Saturday. Scattered showers
possible Saturday, tapering off Saturday night as weak upper
ridging moves through. Another wet Pacific system progged to
impact the area Sunday into Monday bringing more significant rain
and wind along with relatively low elevation snow.
Upr rdg ovhd with Nly flow alf. Wdsprd MVFR/IFR with isold LIFR
in ST/FG in Cntrl Vly thru abt 21z Mon otrw mnly VFR for Intr
NorCal nxt 24 hrs. Sfc wnds genly lgt.