Area Forecast Discussion
Issued by NWS Sacramento, CA

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FXUS66 KSTO 101808

Area Forecast Discussion
National Weather Service Sacramento CA
1008 AM PST Sat Dec 10 2016

Wet weather through this evening. Periods of wet weather likely
to continue next week, with significant mountain snow possible
Tuesday to Thursday.


A very moist plume of Pacific moisture continues to bring
widespread light precipitation to the valley and more moderate to
heavy precipitation over the mountains. As of 1000am PST, the
mountains 2-4 inches of rain with the heaviest amounts from Nevada
county up through eastern Butte and western Plumas counties. More
is expected today valley precipitation winding down this
afternoon up north and not until mid to late evening for the
Sacramento and Modesto, respectively, as the moisture plume shifts
southward and drier air moves in.

Snow levels with this warm event are quite high this morning,
over 9000 feet. This will keep snow accumulation from being an
issue except over high peaks today.

Models are shaping up for a very wet period from Tuesday through
Thursday with moderate snow levels (4000 to 6000 ft from north to
south).   JClapp

Moisture tap from the subtropics into northern California
continues into the extended period. GFS and ECMWF both showing
precipitation over the entire CWA on Wednesday. Slight ridging
over the southwest U.S. should bring moderately high snow levels.
Upper shortwave trough dropping into norcal on Thursday will keep
precipitation going on Thursday. Moderate precipitation will be
possible over the higher elevations where orographics play a role.
Models show main upper trough digging into the Great Basin on
Friday bringing northerly flow aloft to the north state. This
northerly flow should bring drying but norcal remains under
cyclonic flow so some light precipitation may be possible in moist
airmass. At this time, all extended models bring drying next
Saturday. Have therefore kept end of extended period dry with
clearer skies but cool northerly flow will keep daytime high
temperatures below normal.


Widespread MVFR/IFR continue next 12 to 18 hours as Pacific
frontal band slowly moves southeast across norcal. KRDD and KRBL
will become VFR by early aftn. Gusty southerly winds over central
Valley weakening, but strong gusts of 30 to 35 kts still over
exposed mountain ridges. JClapp



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