Storm system brings periods of heavy snow over the mountains, showers and isolated thunderstorms elsewhere and gusty wind at times early this week. Drier conditions return next weekend.
Discussion
Main surface low continues to lift northward just off the northwest coast of California and slowly fill early this morning. Surface pressure gradient has relaxed across much of the area since Sunday evening, but remains tight across the northern Sacramento Valley (SAC-RDD gradient is currently around 7 mbs.) where gusts of 40-50 mph are still occurring.
Further to the south, gusts are mainly in the 25-35 mph range across the remainder of the Sacramento Valley, and in the 30-45 mph range over the foothills and mountains. Winds will continue to taper this morning. Precipitation has become less widespread overnight with lines of showers becoming oriented parallel to the mid and upper flow.
One line of persistent heavy rain has been anchored near the Grass Valley area early this morning where more than 3 inches of rain has fallen since midnight. Only a few reports of minor flooding in this area, and Flood Advisory remains in effect. This may continue several more hours, but eventually less rain is expected by later this morning as the upper trough swings around.
In the Sierra, periods of heavy snow will continue across the higher elevations today before decreasing tonight. Snow levels will remain around 6000 feet before lowering later today.
Wind will also drop off today. Major travel impacts are expected over the higher passes.
Scattered thunderstorms will be possible this afternoon and will also pose a risk for heavy rain, so the Flood Watch for the valley and foothills will remain in effect.
Less impactful weather is expected Tuesday through mid-week as the large upper trough gradually shifts east.
Extended Discussion (Friday through Monday)
Long wave troughing over CA early Friday progresses into the Great Basin as upper low to the north drops into it Friday into Saturday. Bulk of associated dynamics remain east of the CWA with main threat for showers over the eastern foothills/mountains Friday into Friday night.
Drier weather with gradual warming then expected next weekend into early next week as interior NorCal comes under influence of upper ridging.