Federal weather forecasters on Thursday predicted the development of drought-producing La Niña pattern that could to last through the winter.
There is a 60% chance that La Niña will develop during the Northern Hemisphere fall, with a 55% chance the pattern will continue through the winter of 2020-21, the National Weather Service’s Climate Prediction Center said in its monthly forecast.
Atmospheric rivers (ARs)—long, sinuous corridors of water vapor in motion in the lower half of Earth’s atmosphere—are a key aspect of California’s cool-season climate. ARs are in many cases pretty unremarkable when they’re out over the open ocean, visible on satellite as a narrow ribbon of cloudiness and (usually) light precipitation. But when these moisture plumes attach themselves to wintertime low pressure systems and make landfall along the California coast, the consequences can be dramatic—prolonged heavy rain and mountain snow often result, along with sometimes powerful winds.
Expanding and intensifying drought in Northern California portends an early start to the wildfire season, and the National Interagency Fire Center is predicting above-normal potential for large wildfires by midsummer.
Mountain snowpack has been below average across the High Sierra, southern Cascades and the Great Basin, and the agency warns that these areas need to be monitored closely as fuels continue to dry out. The agency also cites a warm, dry pattern in Oregon and central and eastern Washington, and assigns all of these areas a higher-than-average likelihood of wildfires in July.
Rain and snow continued to fall Thursday on parts of California as a wet spring following a no-show winter pushed back against resurgent dryness that spread over three-quarters of the state this year.
Mountain peaks from the Sierra Nevada to major ranges crossing Southern California glistened with new coats of white as hillsides sported increasingly vivid shades of green fueled by precipitation that began in March after a largely withering January and February.
The latest storm entered the state from the north last weekend and slowly moved down the coast.
A winter-like storm system will continue to bring rain, snow and cooler air to California into midweek.
While the month of February featured nearly bone-dry conditions across the Golden State, a series of late-season storm events are helping to minimize concerns for the dry season ahead.
California mountains are blanketed in snow and much of the state has had plenty of rain in a remarkable March turnabout from the extremely dry first two months of the year.
The most recent statewide storm started during the weekend and, despite diminishing, snow snowfall and showers were still occurring here and there.
In the Sierra Nevada, Homewood Mountain Resort on the west shore of Lake Tahoe reported late Tuesday a storm total of 114 inches (289.5 centimeters) of snow at its summit and 74 inches (188 centimeters) at the base.
The final days of winter will bring more stormy weather across much of California.
A storm started off the weekend along the northern California coast, helping to produce snow and blizzard conditions across the Cascades and northern Rockies.
The storm will shift south along the California coast through early week, bringing precipitation to central and southern California.
February has been amazingly dry in California, if anyone hasn’t noticed. No precipitation at all in February, a dry forecast, about 51% of seasonal Sacramento Valley precipitation (a bit less for the San Joaquin and Tulare basins), and only about half (45-57%) of normal snowpack for this time of year. Unless March is wet, this dry year seems likely to advance the onset of the fire season and threaten forest health this year.
Reservoir levels are still not bad for this time of year. Many are fuller than average, perhaps reflecting some snowpack loss. Some other reservoirs are a bit low. This is inherent in the first year of a drought, low precipitation and snowpack, but mostly ok reservoirs.
Groundwater has recovered somewhat from the previous 2012-2016 drought, better in the north, but less in the state’s more overdraft-prone areas in the San Joaquin and Tulare basins.
A fast-moving storm will bring a chance of rain and snow in San Diego County Thursday before exiting by midday Friday, according to the National Weather Service. The cold front moving down the coast is expected to bring a drop in temperatures, gusty winds out of the west, a chance of rain everywhere except deserts areas and a chance of snow in the mountains, forecasters said.
The rain is expected to start falling this evening, then linger overnight before the storm system leaves by Friday afternoon. Rainfall totals could reach 1 inch in the mountains, while a quarter- inch of rain is expected in coastal areas and the western valleys.
San Diego County will experience a second day of heavy rain Wednesday from a cold storm out of the north that tapped into tropical moisture from the south as it surged into Southern California, according to the National Weather Service.
The entire region will get soaked, and all areas are under a flash flood watch. But the rain will be heaviest in northern and central San Diego County, especially along Interstate 15, from roughly Escondido north to the county line, forecasters say.
The Water News Network is San Diego County’s source for water news and information.
