March 16, 2021 – Dry weather today and Wednesday with chilly morning temperatures. Precipitation chances return Thursday and Friday.
Discussion
Skies have cleared across the region other than stratus packed in along the crest of the Sierra and in some of the mountain valleys of the southern Cascades. North winds are holding temperatures in the lower to mid 40s so far across the northern half of the Sacramento Valley, but current readings are in the 30s to around 40 elsewhere in the valley.
Widespread valley frost is expected through most of the Central Valley early this morning with most dew points in the mid 20s to lower 30s, clear skies and generally light winds. Minimum temps will likely drop into the upper 20s across the coldest portions of the Central Valley. The far north end of the valley (Red Bluff northward) will be a bit tricky as both LAV and MET guidance keeps keeps minimum temperatures up there in the upper 30s and lower 40s with just enough north wind persisting (MFR-RDD gradient remains between 5-6 mbs).
Dry and milder weather expected today and Wednesday and the ridge presently over the eastern Pacific transits the area. Highs will be considerably milder over the mountains, but the valley won’t mix completely beneath the subsidence inversion, so highs will still remain a little below average for mid-March. With mainly clear skies and light winds, another chilly night is expected tonight with frost potential again in the Central Valley.
Little change with timing and strength of the Thursday/Friday system. Most of the significant travel impacts will likely hold until Thursday afternoon and Thursday night.
Snow levels will be higher than the most recent system, but the associated moisture plume will be deeper (latest TPW satellite imagery shows the plume being drawn northward over the Pacific east of Hawaii) with a little higher QPF forecast, and 12-18 inches of snow accumulation along the northern Sierra crest. Upper trough moves through Friday with scattered showers and perhaps a few thunderstorms.
Extended discussion (Saturday through Tuesday)
Troughing will be set up over the west for the start of the extended period. The main energy will be off to our east on Saturday bringing mainly dry weather but a few mountain showers will be possible come the afternoon. Short wave ridging will keep things dry on Sunday.
On Monday a short wave trough will drop into the PacNW and dig into the region. This will bring the return of a few light showers over the higher elevations for Monday. Stronger upper level ridging will build in by the middle part of next week.
Below average highs will gradual warm to near average and to above average by the middle part of next week.