November 6, 2021 – Light rain showers, and some high elevation snow showers are expected today. A wetter weather system is forecast early next week, bringing widespread rain and mountain snow.
Discussion
Some very light precipitation has continued over night across the northern mountains where amounts have ranged from a few hundredths of an inch up to 0.20 inches locally. Otherwise dry conditions persist as clouds continue to stream into NorCal from the west- southwest ahead of the slowly approaching frontal system. Current temperatures are fairly mild ranging from mainly the 30s and 40s in the mountains, to the upper 40s to upper 50s across the Central Valley.
Mostly light precipitation will be on the upswing across mainly the northern half of the forecast area by midday as the front sags further south and the offshore wave (presently near 35N/135W) moves onshore. CAMS continue to indicate potential for some isolated thunderstorms this afternoon over the northern Sacramento Valley behind the front.
QPF will be generally light, mostly a few hundredths of an inch in the valley with around 1/2 to 3/4’s of an inch in the northern Sierra. Snowfall up to 6 inches will be possible this afternoon and evening over the crest of the northern Sierra, and some travel impacts can be expected across the higher passes. A Winter Weather Advisory has been posted for elevations above 6.5k ft.
Precipitation winds down this evening and a break is expected Sunday through most of Monday. Clearing skies and lighter winds may allow for some patchy frost to develop early Sunday morning across the north end of the Sacramento Valley.
Still looks like a more impactful system will affect the region later Monday into Tuesday with heavier precipitation and potentially stronger winds than recent systems. Still lots of spread in the ensemble precipitation amounts, but looks like most of the valley will see a minimum of an inch of rain while the foothills and mountains see about 2-3 inches. Lower snow levels and heavier snow amounts may bring increasing travel impacts to the northern Sierra highways, and possibly on Interstate 5 north of Redding.
Extended Discussion (Wednesday through Saturday)
A few showers may linger in the higher elevations early Wednesday as the upper level trough pushes to the east. Dry weather will then set in for the remainder of the period as upper level ridging builds in from the west. Ridging will be strong by the end of the week but may flatten some into next weekend. Temperatures will remain cool on Wednesday but will warm to above average by the end of the week.