An active weather pattern continues with mountain snow, rain, and gusty winds expected to impact travel. There will be a brief lull Sunday, followed by a weaker system.
Winter Storm Warnings:
- Until 10 PM tonight for elevations above 3500 feet for the Shasta County mountains
- Until 10 PM tonight for elevations above 5000 feet for the Southern Cascades & Sierra
Wind Advisory: Until Noon today for portions of the Sacramento Valley and Delta with gusts of 45 to 55 MPH.
Discussion
The forecast for stormy weather is on track with windy conditions, and moderate to heavy precipitation continuing, with the strongest winds, heaviest rain and snow expected through this morning.
Winds overnight in the Central Valley have been strongest over the northern Sacramento Valley and adjacent foothills with gusts to 55 mph at Red Bluff Airport, 45 mph at Redding Airport. Sacramento International and Executive airports have measured gusts up to 37 mph, 36 mph at Stockton Airport. Some trees have been reported down by Caltrans & the CHP, so use caution while out driving this morning. These winds could also make driving high profile vehicles difficult. Winds are expected to peak by late this morning. A Wind Advisory continues for the Sacramento Valley, Delta, and northern San Joaquin Valley through noon today. Gusty winds are being observed in the mountains, with gusts generally around 55 to 65 mph, though some high ridges are seeing locally higher readings. These winds along with heavy snow could lead to periods of whiteout conditions, making driving very hazardous over mountain roads.
Moderate rain continues across the area, with embedded bands of heavier showers. Slick roads and gusty winds have led to quite a few accidents reported by the CHP overnight, so motorists should be extra cautious, especially through the morning hours. Heaviest rain so far has been over the northern portions of the areas. Highest precipitation totals over the past 24 hours (through 3 AM) were up to 3 to 5 inches over northern Shasta County, though some of that has fallen in the form of mountain rain.
There will be a quiet and dry weather pattern in store from mid to late next week as building upper level ridging dominates. While the building ridge should support generally clear skies, this may also provide a good environment for fog to develop along with cooler morning temperatures. This should also allow afternoon high temperatures to rise to slightly above normal. Generally light diurnal/terrain driven winds are then expected through the remainder of the week. Clusters are hinting at the next potential for a precipitation event on Saturday, though this currently looks like a relatively quick moving system. bove normal. Generally light diurnal/terrain driven winds are then expected through the remainder of the week. Clusters are hinting at the next potential for a precipitation event on Saturday, though this currently looks like a relatively quick moving system. in snow. In the Valley, 24 hour totals have ranged from around 1.25″ for Redding Airport, to 0.25″ for Sacramento, 0.20″ for Stockton, and 0.07″ for Modesto.
Rain rates have generally been 0.05″ to 0.15″ per hour, which has so far limited road flood potential. A more unstable area of convective showers and thunderstorms is evident off the coast on radar and lightning detection, approaching the Bay Area. A strong thunderstorm off the coast has had a Special Marine Warning issued by NWS Monterey.
Convective Allowing Models show heavier showers and isolated thunderstorms moving inland into interior northern California along and south of the I-80 corridor over the next several hours. These could bring heavy showers and hail. While instability is relatively limited, there is quite a bit of shear, so these storms will be closely monitored for severe weather potential.
Widespread chain controls were in effect for mountain roads across the area. Check the latest road conditions from CalTrans online at quickmap.dot.ca.gov. Periods of moderate to heavy snow will continue through this evening, with an additional 1 to 2 feet of snow over the northern Sierra and southern Cascades expected, locally higher over peaks, with now levels generally be 4000 to 5000 feet. Wind gusts of 55 to 70 mph are expected, locally higher over high elevation peaks. Wind gusts to 40 to 55 mph are possible. Another 3 to 12 inches of snow is expected over the mountains of Shasta County and the northern Coastal Range above 3500 feet. Winter Storm Warnings continue for those areas. Snow covered and slippery roads, chain controls, and reduced visibilities will contribute to travel delays and could become very difficult.
Saturday afternoon will see the winds begin to diminish, with Valley showers becoming light and winding down by mid afternoon. Mountain snow will continue through the day but gradually diminish in intensity, with just lingering snow showers by late evening.
Dry weather, mostly sunny conditions and and lighter winds are expected Sunday. The next round of active weather begins on Monday late morning and continues into Tuesday morning , though this system will be quick and far weaker than the current system. NBM forecast snow totals have trended back up a bit for Lassen National Park and the mountains of Shasta County, which could see 2 to 6 inches of snow from 3000 to 4000 feet, up to 6 to 12 inches for above 4000 feet, while the northern Sierra could see around 1 to 5 inches above 6000 feet. Rain with this wave will be considerably less with only 0.05-0.25″ forecasted for the Valley and 0.15-0.75″ over the foothills and mountain areas. Highest precipitation amounts are expected over northwestern Shasta County, with 0.5-1.00″ of rain forecast over a 24-hour period.
Extended Discussion (Wednesday through Saturday)
There will be a quiet and dry weather pattern in store from mid to late next week as building upper level ridging dominates. While the building ridge should support generally clear skies, this may also provide a good environment for fog to develop along with cooler morning temperatures. This should also allow afternoon high temperatures to rise to slightly above normal. Generally light diurnal/terrain driven winds are then expected through the remainder of the week. Clusters are hinting at the next potential for a precipitation event on Saturday, though this currently looks like a relatively quick moving system.