NWS Area Weather Forecast Discussion
County Warning Area [CWA]: STO Regional NWS Weather Office: Sacramento, CA
FXUS66 KSTO 011040
Area Forecast Discussion
National Weather Service Sacramento CA
340 AM PDT Wed Apr 1 2020
Dry and mild weather expected this week. Breezy north winds expected
today and Thursday. A pair of storms move in over the weekend
into early next week bringing rain, gusty winds and accumulating
mountain snow and travel problems.
An upper low over western Canada and the Pacific Northwest will
shift eastward today. Dry weather is expected today except for a
few lingering light showers possible this morning in the Sierra
north of I-80. Dry northerly flow will develop behind the
departing low as Pacific ridging extends eastward. This will
increase the surface pressure gradient, with some breezy northerly
winds today and tomorrow. Gusts up to 25-35 mph will be possible
each day in the Valley.
Valley highs today are expected to be about 5 to 10 degrees
cooler than yesterday, generally in the mid 60s. This is 3 to 5
degrees below normal for this time of year. Temperatures on
Thursday and Friday will rise back to around normal levels.
A shortwave progresses towards the west coast Friday night, with
precipitation chances beginning early Saturday morning north of
I-80, then spreading southward. Exact timing of precipitation
remains somewhat uncertain, with the ECMWF slower than the GFS,
but ensembles and deterministic models agree by mid-afternoon that
the possibility for precipitation will be widespread across the
area. Snow levels are expected to be around 4000-5000 feet, with
accumulating snow bringing potential travel problems. EK
.EXTENDED DISCUSSION (Sunday THROUGH Wednesday)...
Stronger Pacific storm drops down the West Coast Sunday into
Monday bringing widespread precipitation over interior NorCal with
significant snow expected in the mountains. Snow levels range from
around 3500 to 4500 feet with 1 to 2 feet possible over the higher
elevations of the Sierra Nevada. Deterministic models begin to
diverge significantly by Tuesday with EC keeping strong closed low
meandering off the CA coast through early Thursday while GFS
weakens low and moves it through SoCal Tuesday. EPS/GEFS support
EC solution so attm forecast leans towards this with unsettled
weather advertised through midweek.
Isold IFR/LIFR conds poss in mtn vlys in fog til abt 18z tda otrw
VFR conds ovr intr NorCal nxt 24 hrs. Lcl Nly sfc wnd gsts up to
25 kts poss in Nrn Sac Vly btwn 17z-01z. Lcl SW-NW sfc wnd gsts
up to 35 kts poss ovr hyr mtn trrn til abt 03z Thu.