April 19, 2017 – Shower chances into Thursday then dry and warmer for the weekend.
Clear to partly cloudy skies across interior NorCal early this morning. The showers and thunderstorms that were over northern Shasta County earlier in the night have for the most part moved north into Siskiyou County. With less cloud cover, current temps are cooler compared to 24 hours ago ranging from the mid 20s and 30s in the mountains to the 40s and lower 50s elsewhere.
Satellite imagery shows the leading edge of the next system already approaching the NW coast of California. Showers are expected to spread into the northern Coast Range this afternoon, then move inland across interior NorCal overnight tonight into early Thursday.
Moderate amounts of QPF will be possible across the west slopes of the northern Sierra Nevada due to orographic enhancement. Snow levels lower to 4500 to 5500 feet by early Thursday with some light accumulation at pass levels possibly impacting travel. Showers Thursday morning gives way to mainly dry conditions by the afternoon as increasing subsidence spreads in from the west.
Dry weather with warmer temperatures then expected Friday and Saturday as large scale upper ridging from the EPAC shifts over NorCal. Around 10 degrees of warming expected by Friday with highs around 80 for the Central Valley with 50s to lower 70s for the mountains and foothills.
Another trough is forecast to brush across the far northern portion of the state Saturday night and may bring a few showers to the northern mountains.
Extended discussion (Sunday through Wednesday)
Model forecasts have a general trough pattern across the west starting Sunday, but main lift associated with the low pressure system will remain to the north of the forecast area. Some light precipitation cannot be ruled out for the northern mountains, but developing precipitation looks unlikely at this point for Sunday.
Upper level northwest flow and approaching jet stream across northern California will take place to start next week. As a result, chances for rain will return to the forecast through mid week with generally light precipitation expected.