Active weather pattern the remainder to this week and into next week with multiple rounds of precipitation. Flood Watch from Friday afternoon through late Saturday night. Minor to moderate flooding of rivers and small streams. Areal flooding of flood-prone locations expected Friday through the weekend due to heavy rain.
Discussion
First round of precipitation is moving through the region. Initially snow levels will be low but as the warm front moves through snow levels will rise through out the day and tonight. Snow levels are currently near 3000 feet along the coastal range to 4000 feet over the Sierra.
The warmer air will move into the coastal range this morning and by early afternoon snow levels will rise above 7000 feet so have ended the time period at 2 pm this afternoon. A cold pocket or air is forecast to linger over Shasta County into the evening hours so snow levels will be slow to modify. Further east over the Sierra Nevada snow levels with rise above pass levels after midnight tonight.
After the snow levels rise above pass levels they are expected to remain high above pass levels until late Saturday when they lower so may need a Winter Weather Advisory for the tail end of the Saturday’s storm.
For the flood advisory have increased the coverage to include foothills in Butte County and pushed back the timing of the watch period to start late in the day Friday to match up closer to when the strongest front will move through.
Some of the foothills may start to see some issues with small creeks Friday evening with all the orographic precipitation slowly building up. The valley’s potential for flooding concerns looks more like later Friday night and Saturday.
Lots of orographic influence and snow melt should bring sharp rises to rivers and streams below the snow level with some messy slushy streets within the remaining snow pack.
Winds look breezy on Friday but as the low moves though on Saturday there is a chance for windy conditions to develop starting early in the day with the focus of the stronger winds over the southern half of the forecast area and the potential for breezy conditions over the northern half.
New Years Eve celebrations are starting to look drier for most locations for the mid to late evening hours.
Behind this system New Years Day is looking dry with maybe some breezy conditions so not expecting any morning fog at this time.
Extended Discussion (Monday through Thursday)
A series of systems bring the potential for more rain and mountain snow next week, with the unsettled pattern continuing. Exact timing remains uncertain, but confidence is high in a general wet pattern continuing with three systems potentially on tap for Northern California, Monday, Tuesday and Wednesday. While these storms don’t look as wet or as strong as this current event, cold air should bring lower snow levels next week and winter travel problems could be an issue at times.