Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Sacramento California
909 am PST Sat Dec 27 2014
mainly dry weather will continue for the next few days, with
north winds and frosty overnight lows. Stronger north winds and a
few mountain showers may be possible for early/middle next week.
northern California remains under dry northerly flow between a
strong eastern Pacific Ridge and deep trough over The Rockies.
Pressure gradients relaxed overnight, which when combined with
clear skies allowed for strong radiational cooling. Most valley
locations cooled to the 30 to 35 degree range, with mountain
locations dipping into the 10s to 20s. Many valley locations
experienced their first frost this season.
High temperatures are not expected to vary much the next few
days, with lower to mid 50s expected for the valley and 30s to
40s for the mountains. These forecast highs are within a few
degrees of normal.
Low temps will remain on the cool side for the next several days
as well. The current expectation is that increased cloud cover
tonight will help to keep lows a bit warmer than this morning.
A shortwave trough moves out of western Canada and into norcal
late Monday into Tuesday with breezy to strong northerly winds
Monday night through Tuesday night. The drier trough may still
bring a slight chance of light showers Monday night into Tuesday
over the Sierra/Cascades and generally southward of I-80 in the
valley. Snow levels will be roughly 2000-3000 ft with only a few
inches of snowfall expected above approx 2500 ft.
Extended discussion (wednesday through saturday)
High pressure pushing in over the Pacific northwest and a low over
Southern California with strong northerly flow between over the
north state. 06z GFS has a 10-12 mb surface gradient from mfr to
SAC Wednesday morning. This tight gradient combined with good
upper level support will make for breezy to windy conditions
across the forecast area Wednesday. Cool air out of Canada being
brought to norcal by northerly flow will keep temperatures on the
cool side day and night. Minimum temperatures early Wednesday will
be on the chilly side kept up slightly by the brisk northerly
winds. Daytime highs will be below normal despite the relatively
clear skies. Pressure gradients relax a bit by Thursday as the
upper low moves from socal to northern Arizona. The lighter winds
will allow for colder minimum temperatures with near freezing
valley temperatures expected new years morning. Daytime
temperatures warm a bit on Thursday afternoon as offshore high
pressure pushes inland a bit and airmass warms slightly but
daytime highs are still expected to come in below normal.
A slight warming trend continues on Friday and Saturday as high
pressure remains dominant over the West Coast. Fair skies, lighter
winds and a cool airmass will make for cold nights and cool days
through the end of next week. Extended models are not in great
agreement however with Gem model digging a low down the coast for
a threat of precip towards the end of next Saturday. Will keep
forecast dry and cool for now going with GFS and European model (ecmwf) models.
VFR conditions expected next 24 hours. Light winds generally below