December 11, 2017 – Dry weather into next weekend with mild days and chilly nights.
Clear skies across interior NorCal except for some high clouds south of I-80 associated with the closed low near Baja California. Current temperatures are similar to readings from 24 hours ago and range from the teens in the mountain valleys, upper 20s to upper 30s in the Central Valley and 40s to lower 50s across the foothill and west slopes thermal belts.
Upper high shifts slightly east into Tuesday as a short-wave trough rides the ridge towards BC. Ridge then retrogrades back to the West Coast Wednesday with dry weather persisting. Little change in the weather through the week with some morning patchy fog or frost possible in the Central Valley. Highs will continue to be above average with record highs possible across portions of the northern Sacramento Valley.
Extended discussion (Friday through Monday)
Upper trough moving through the Pacific Northwest on Friday will weaken persistant west coast ridge bringing cooling most areas especially northern CWA. At this time it appears any precipitation with this system will remain north of the forecast area. Dispite cooling, daytime highs will remain above normal. Upper ridge rebuilds briefly on Saturday will little change expected in daytime highs. Another shortwave trough rides over the ridge on Sunday. Models differ on strength of this shortwave with GFS currently a little deeper. Far northern California could see a little light precipitation but probability remains fairly small. Otherwise, extended forecast remains dry with above normal daytime highs and relatively light winds.