Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 180500

900 PM PST Wed Dec 17 2014

Yet another wave of rain/snow moving in tonight. A brief break in
precipitation some areas on Thursday. Next frontal passage on
Friday with light to moderate rain and higher elevation snow into
Saturday morning. Mountain showers possible over the weekend but mainly
dry in the valley. Dry all areas Monday through mid week under
west coast high pressure ridge.


A weak cold front is moving through the interior this evening.
Light amounts of precipitation are spreading through the
interior. Amounts will generally be less than a quarter
inch for all areas.

Snowfall will be picking up after about 11 pm. Models indicate the
intensity of precipitation decreasing again as it moves over the
Sierra and will generally bring less than 3 inches of snow during
the overnight hours. Snow levels are generally above 4500 feet but
may get down locally to around 4000 feet overnight. Some patches
of fog will likely develop in the late night and morning hours but
it may not be too bad in the morning with some cloud cover moving
into the region behind this front. Most areas will be drying out on
Thursday with some lingering showers over the mountains and north
end of the valley.

Another weak system for the area will move through on Friday
followed by a building ridge of high pressure for the weekend.
The GFS is the deepest with the weekend wave keeping precipitation
mainly north of I-80 while the NAM does the same but in the
mountains and limits any valley precipitation to the north end of
the Sacramento Valley. The rest of California will be drying out.

.Extended Discussion (Sunday through Wednesday)

Medium range models similar in transitioning to a drier weather
pattern over the weekend into early next week. Some light precip
continues to be depicted over the Shasta mountains Sunday,
otherwise dry weather with the main weather concern being impact
of valley stratus and/or fog nights and mornings. Models
strengthen upper high in EPAC with associated upper ridge building
over Interior NorCal.

Longer range models are struggling with the evolution of a
deepening trough over the Pacific Northwest toward the middle of
next week. The ECMWF and Parallel-GFS offer a solution that brings
the system farther westward, which could bring some low elevation
snow to the Sierra. The lo-res GFS and GEM swing the trough through
the Rockies, which would be a drier solution for Northern
California. For now, we`ve included "chance" wording in the
forecast focusing on the Sierra.

Dang / JClapp



Trof movg E tngt then upr rdg Thu. For Intr NorCal, areas
MVFR/IFR tda into Thu mrng in prec with lcl LIFR omtns. Sn lvls
040-045 ft AMSL.


.STO Watches/Warnings/Advisories...
winter weather advisory until 4 am pst thursday above 4000 feet
in the west slope northern sierra nevada...western plumas
county/lassen park.


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