February 15, 2019 – A strong storm continues to bring precipitation to the region through the weekend. Heavy snow will continue in the mountains with minor accumulations possible in the foothills through early Sunday. Additional rainfall expected in the Valley today with chances decreasing through the weekend.
Discussion
Satellite imagery this morning indicates the main upper low is located over the Pacific west of Oregon with bands of precipitation continuing to move over the NorCal interior.
Surface winds are generally from the southwest limiting strong wind gusts across the Valley overnight with the strongest gusts seen around 35 mph. With the gradient expected to decrease today, have opted to cancel the Wind Advisory early this morning. Periods of gusts up to 35 mph, however, will continue to be possible through early Saturday morning.
The main hazard through the weekend will be the snowfall impacting the Sierra-Southern Cascades and Shasta County mountains. Current radar shows heavy snow already falling in the Sierra with continued heavy snow forecast through the day into Saturday. Snow levels are expected to remain around 2500-3000 feet with an additional 3 to 6 feet expected through early Sunday morning, with local amounts even higher.
Have extended the Winter Storm Warning for the Sierra through early Sunday morning due to the additional amounts up to 2 feet expected Saturday in the Sierra. Additionally, areas around I-5 in Shasta County may see up to a foot of snow creating hazardous travel conditions mainly through Saturday morning, although additional light amounts may be seen through the day Saturday.
A shortwave ahead of the main trough will move across NorCal Saturday night into Sunday bringing with it colder air and lower snow levels. Snow levels Sunday morning will drop to 800-1500 feet, although snowfall at this time will be decreasing and only light amounts up to 2-4 inches are expected at this time.
As for rainfall, additional amounts from a half to an inch to an inch can be expected in the Valley, with 1 to 4 inches in the foothills. There remains a slight chance for thunderstorms mainly late morning into the afternoon across the Valley today which may lead to localized areas of heavy rainfall. Urban and small stream flooding is still a concern today as rain continues. Rain in the Valley will not be continuous through the weekend with periods of dry weather expected.
Extended Discussion (Tuesday through Friday)
Extended period starts out dry under light northerly flow aloft between upper trough over the Great Basin and an upper ridge over the eastern Pacific. Daytime highs will climb several degrees under fair skies but will still remain a few degrees below normal. Only minor changes expected Tuesday as models drop a weak trough southward across the north state. Models drop a stronger upper low out of western Canada and into the Pacific Northwest on Wednesday. Models differ some on track of this system southward but at this time this appears to be somewhat of an inside slider mainly affecting the north CWA and Sierra Cascade range. Entire forecast area could see a threat of precipitation Wednesday night or Thursday but this relatively dry and cold system is not expected to drop significant amounts of precipitation. Snow levels with this cold system will remain relatively low.