An active weather pattern continues into early next week with periods of rain, high-elevation snow and gusty wind. Heaviest rainfall rates expected Sunday night into Monday. Wind Advisory until 7 PM PST this evening for Central Sacramento Valley-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley. FloodWatch from Sunday afternoon through late Monday night for Central Sacramento Valley-Motherlode-Mountains Southwestern Shasta County to Western Colusa County-Northeast Foothills/Sacramento Valley-Northern Sacramento Valley-Southern Sacramento Valley. Winter Storm Warning until 10 PM PST Monday for West Slope Northern Sierra Nevada-Western Plumas County/Lassen Park.
Discussion
Showers cover the region early this morning as the upper trough off the northwest coast lifts toward the PacNW. Precipitation amounts since Friday afternoon have ranged from a few hundredths of an inch in the Sacramento region, 0.25″ to 0.50″ over the northern half of the Sacramento Valley, and up to an inch over portions of the Coast Range and Shasta County Mountains.
Southerly wind has been slow to increase overnight, but is beginning to finally pick up as southerly surface gradient tightens. Still looks like gusts of 30-40 mph will be possible today across the northern Sacramento Valley and a wind advisory remains in effect into this evening.
Heaviest QPF today will be across the northern half of the forecast area as southerly flow leads to orographic enhancement over the far northern Sierra and mountains north of Redding. There may be enough breaks in clouds and precipitation further south to build up enough instability to pop an isolated thunderstorm this afternoon, but confidence is low.
Radars indicate the snow level is currently around 6.5-7k ft, and around 2-6 inches of snow will be possible near the higher northern Sierra passes. A winter storm warning remains in effect.
The next wave of precipitation moves in tonight into Sunday morning, followed by a relative minimum Sunday before the final wave of this series moves in Sunday night and Monday. 1.5″ to 3″ of rain will be possible through Monday in the valley with 4″ to 8″ in the mountains.
Rises in creeks and streams will be possible, especially by Monday and a floodwatch remains in effect for late Sunday through Monday.
A couple feet of additional snowfall will be possible for the higher Sierra passes leading to very difficult travel conditions. Another relative break is forecast Tuesday before another round of precipitation moves in by Tuesday night.
Extended Discussion (Wednesday through Saturday)
Several relatively weak vort maxes progged through interior NorCal Wednesday with some light precip possible. Lingering showers over the Sierra possible early Thursday, otherwise drier weather Thursday into Saturday as EPAC upper level riding builds inland.
Warming trend expected through the extended forecast period with above normal temperatures beyond midweek.