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FXUS66 KSTO 121130

Area Forecast Discussion
National Weather Service Sacramento CA
330 AM PST Tue Dec 12 2017

Dry and mild weather into early next week with chilly nights in
the valleys.


Clear skies across interior NorCal except for a few high clouds.
Current temperatures are similar to 24 hours ago and range from
the teens in the mountain valleys, 30s to lower 40s in the Central
Valley, and 40s to mid 50s elsewhere.

Strong ridge over the West forecast to retrograde to along the
coast through mid-week, then a short-wave trough is forecast to
flatten the ridge as it moves over the top on Friday.
Precipitation associated with the wave on Friday is forecast to
remain north of the region.

Little overall temperature change expected through the end of the
week with dry and mild weather continuing under a strong
subsidence inversion. Record high temperatures will be possible 
at the north end of the Sacramento Valley.

Chilly overnight temperatures will continue in the Central Valley
beneath shallow nocturnal radiative inversions that develop each
night with patchy frost likely.


Upper ridge of high pressure over the eastern Pacific and west 
coast will bring fair skies and well above normal temperatures on 
Saturday. A tight northerly surface gradient combined with an 
upper level northerly flow will bring breezy north winds most 
areas especially down the northern Sacramento valley. Upper ridge 
axis shifts over the west coast Sunday and Monday bringing 
continued warmer than normal temperatures while weakening surface 
gradients and upper level support bring lighter winds. Upper ridge
begins to break down next Tuesday which should bring slight 
cooling trend going into mid week but daytime highs will remain 
above normal. 


VFR conditions expected over the next 24 hours at TAF sites except 
areas of MVFR/IFR in fog southern Sacramento and northern San
Joaquin valleys through about 18z. Winds generally below 10 knots.


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