Dry and mild today, weak storm system on tap for Wednesday night into Saturday

March 6, 2018 – Dry and milder weather through mid-week, then precipitation chances return for the second half of the week.

Discussion

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Varying amounts of high clouds cover interior NorCal early this morning. Current temperatures are milder (considerably milder in the thermal belts) compared to 24 hours ago and generally range from the upper single digits in the mountain valleys to the mid 30s to lower 40s in the Central Valley. Foothill and mountain thermal belts are in the 40s.

The offshore closed low remains quasi-stationary centered to the west of 140W and will remain so today before starting to lift out toward the PacNW tonight. The short-wave ridge over NorCal will maintain dry and mild weather across the region today and Wednesday with variable high clouds.

The next weather system is forecast to shear apart as it moves into NorCal Wednesday night and Thursday. Generally light QPF is expected with higher snow levels compared to last week’s systems. Generally light precipitation may continue across the region Friday as deeper moisture continues to move up from the southwest interacting with the lingering weak frontal boundary.

Extended discussion (Saturday through Tuesday)

A series of disturbances will bring periods of precipitation throughout the extended period, though exact timing remains uncertain.

A shortwave trough moves through late Saturday into early Sunday. A decent subtropical moisture plume will be south of the area, bringing higher precipitation amounts into southern and central California. Higher precipitation amounts within our forecast area are now generally expected to be from around I80 southward. There is quite a bit of uncertainty to how much these amounts will be. Current estimates have several inches of snow in the mountains above 6000 feet possible for the weekend, so it is not expected to be a major winter event. Sunday during the day is trending drier.

Model disagreements have increased uncertainty about the arrival time of a wetter system early next week, with a less wet Sunday and early Monday. It may have slowed to be more of a Tuesday- Wednesday system.