Potent early-season storm to bring heavy rain and snow to parts of California
An early-season storm system will bring areas of heavy rain and high-mountain snow to parts of Central and Northern California from Sunday through this upcoming Tuesday.
A developing upper area of low pressure is dropping south across the northeastern Pacific. This system will continue to intensify and position itself just off the coast of Northern California late this weekend before gradually meandering off the California coast early this upcoming week.
This system will tap into an area of subtropical moisture helping create a weak atmospheric river aimed at Northern California extending into Central California. This moisture will bring heavy rain to these areas in California where a widespread 0.50-1.00" can be expected. Isolated higher amounts are possible especially on the western and southern facing foothills and mountains. There will be an increased risk of debris and mud flows where the heaviest rain falls and especially near recent burn scars.
While the greatest concentration of rain and moisture will be focused in Northern and Central California, some rain will also extend into coastal parts of Southern California and farther north into Oregon and south-central Washington.
This system originates over cold regions so it'll have quite a bit of cold air in the upper-levels, especially as it intensifies. This will allow for some mountain snow in California. The highest peaks of the Cascades and Sierras are the favored areas to see wet snow from late Sunday through Tuesday where a few inches are possible.
The lowland rain and high-mountain snow is much needed for California which has been plagued by historic heat and wildfires recently. Beneficial rainfall will help firefighters currently fighting fires and help initially mitigate fire danger going into the fall season.
This storm system will move inland by midweek and begin weakening, shutting down rain chances for California. A system of this magnitude this early in the season is rare so let's hope this is a sign of things to come during the fall and winter as much of the West needs moisture to help alleviate the ongoing drought conditions.