December 29, 2019 – Rain and high elevation snow return to the region today as a weak storm system tracks over us. Dry weather returns on Monday, which will be accompanied with breezy northerly winds. Mainly dry weather is expected through the New Year with a chance of showers being possible for the Cascades. Wet weather may return for the northern half of the CWA for the weekend.
Discussion
Low pressure currently sits west of British Columbia with its associated cold front trailing down the West Coast. High clouds continue to filter over the region with precip mostly sitting off northwest CA`s coast. Radar shows some light reflectivity over interior norCal, but most of that is likely in the form of virga. Precip chances will increase throughout the day as the front enters the region with the coastal mountains seeing precip later this morning. The rest of the area will experience precip by the afternoon and early evening hours with most areas drying out before Monday morning. Snow elevation for this event will generally be around 4000-5000 feet with the lowest snow levels being up around the Cascades. Snow accumulation is expected to be light but there could be some travel impacts for passes this afternoon and evening.
Behind this system, drier weather moves in and northerly winds will begin to increase late tonight, mainly over the western half of the valley before increasing everywhere during the day on Monday. These winds will help prevent fog from forming for most areas with the exception being the northern San Joaquin valley. Winds generally look to be in the 10 to 20 mph range with some stronger gusts into the 20s. By Monday night, the San Joaquin Valley will once again have the chance for some fog to develop. Eastern Sacramento County, and perhaps even some other areas, may see some fog development if the winds ease up enough.
Dry weather persists into Tuesday, which will be accompanied with lighter northerly winds as high pressure builds over the region. The next chance for showers could be for the Cascades/Shasta County on Wednesday as a weak disturbances slides north of the region.
Extended Discussion (Thursday through Sunday)
Ensembles and operational models continue to show eastern Pacific ridging extending into California during the second half of the week. Light precipitation will be possible, mainly across northern Shasta County. Pattern forecast to flatten late in the week allowing a series of weather systems to begin to affect the area. Still quite a bit of uncertainty on the details, but appears at least the northern zones and northern Sierra Nevada will see a chance for precipitation. Temperatures expected to be a little above average.