December 24, 2019 – A few showers linger over the mountains, but most of the Central Valley will be dry early this week. Another weather system will bring a chance of showers to the region on Christmas followed by dry weather this weekend.
Discussion
Radar indicates isolated showers lingering across the higher elevations of the northern Sierra early this morning. The remainder of the area is under clear skies except for low clouds banked up along the west slopes of the northern Sierra. Patches of fog are beginning to develop across the Central Valley and will likely become more extensive before sunrise. Current temperatures are running cooler compared to 24 hours ago and range from the 20s in the mountain valleys to the 30s through the Central Valley.
Weak lingering trough will continue to support isolated showers over the mountains today, otherwise the remainder of the region will remain dry today. The next system approaches tonight and moves through on Christmas Day. The heaviest QPF will be along the central California coast southward into SoCal as the system digs into northern Baja by early Friday. Most areas of NorCal will see less than half an inch. Snow levels will be quite low (2-3K ft), but the low moisture amounts will only give 1-3 inches of snow accumulation over the northern Sierra.
Dry weather returns Thursday into the weekend with breezy north winds likely limiting overall extent of late night and morning fog.
Extended Discussion (Saturday through Tuesday)
Upper level ridge will be pushing eastward for the start of the extended period as an upper level trough drop south into the region. Ensembles means have moved the trough axis a bit further to the east compared to yesterday this time. They are still holding the solution of the trough coming in from the NW but then dropping south through the area on Sunday. Either way impacts with this system are expected to be low given overall weak forcing and lack of moisture. Light showers move in early Sunday and taper off Sunday night. Snow levels start out low Sunday in the 3000 to 4000 range and rise to 4000 to 5000 feet by Sunday afternoon. Models close that trough off over SoCal on Monday and that will keep cloud cover around but the precip chances are expected to shift south. Upper level ridge builds in Tuesday bringing decreasing clouds. Temperatures throughout the period are expected to be near average for this time of year.