Rain and mountain snow starting on Tuesday through the weekend

November 26, 2018 – Another morning with valley fog. Dry and seasonable temperatures today. Then an active period setting up with a series of low to moderate systems this week with rain and mountain snow.

Discussion

Satellite imagery shows high clouds already beginning to overspread the region. A few patches of dense fog have developed across portions of the Central Valley, mainly from the Sacramento area southward. Current temperatures are mostly a little cooler compared to 24 hours ago and generally range from the 20s in the mountain valleys to the 40s to lower 50s elsewhere.

Upper ridging will continue dry weather across interior NorCal today. Highs will once again be on the mild side, but not as warm as Sunday as cloud cover increases ahead of the next system.

Wet weather returns to the region Tuesday and continues through the remainder of the week. The first system will spread precipitation southward through the region on Tuesday. Snow levels will remain high (above 7-8k feet), so winter impacts will likely be minimal.

Precipitation expected to remain generally light Tuesday night and Wednesday, but stronger system is forecast to approach Wednesday night and Thursday. Model differences continue, but appears a good chance of heavier precipitation and stronger winds.

Extended Discussion (Friday through Monday)

Brief upper ridging moves over the state Friday but still enough lingering moisture around for a chance of light showers especially over the mountains during the morning hours. Snow levels should drop below 5000 feet but light precipitation amounts should keep impacts to mountain travel minimal.

Upper low moves into the Pacific Northwest on Saturday with a Pacific frontal band sweeping through NorCal during the day. Models in fairly good agreement on this and only differ slightly on the timing. Heavy precipitation is not expected with this system but low snow levels will make for some minor mountain travel issues over the Sierra.

Scattered showers continue on Sunday as upper low drops into the Great Basin with best chances over the Sierra Cascade range. nearest the low. Upper ridge forecast to push in over the west coast next Monday so if current model scenario holds next Monday should be a dry day. Looks like a lot of uncertainty as to how long this dry period will last as models diverge greatly after this time.