A powerful hurricane force low pressure system located over the eastern Pacific is set to surge a plume of moisture and damaging winds into the West Coast beginning tonight.
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The greatest impacts, which include damaging winds, excessive rainfall, and extremely heavy snow, is forecast to occur over much of California and into southern Oregon through Thursday.
Widespread rainfall amounts of 3 to 6 inches, with locally higher totals, occurring within a relatively short period of time will have the potential to lead to several instances of flooding throughout the already saturated region.
The highest precipitation amounts are expected to occur over the coastal ranges of California as far south as the Transverse Ranges and throughout the Sierra foothills.
Recent burn scars and other sensitive terrain will have the greatest chances for rapid runoff and mudslides as rain rates potentially exceed 1 inch per hour.
A Moderate Risk (level 3/4) of Excessive Rainfall is in effect along coastal sections of California, where numerous instances of flash flooding are most likely.
For the high terrain of the Sierra Nevada, precipitation will fall mostly as snow and add up to at least 3 feet over the peaks.
Gusty winds will add to the hazardous heavy snow, resulting in potential tree damage and white out conditions.
Strong southerly winds will occur across the remainder of the region as well, with rough surf along the coast and potentially damaging winds spreading into the central valley.
High winds combined with saturated ground conditions could lead to additional downed trees and resulting power outages.
Flood and Flash Flood Watches, High Winds Warnings, and Winter Storm Warnings are in effect from southern Oregon to southern California.
Residents and visitors are urged to check their local forecast before traveling and prepare for potential power outages and/or flooding impacts.
The next system to impact the Golden State is anticipated to spread heavy rain into northern California by Friday night, which could lead to additional flooding concerns.
The other major weather story over the Lower 48 includes an unwinding winter storm stretching from the Upper Midwest to northern New England.
Light to locally moderate snow is possible throughout the Upper Midwest/Great Lakes as a meandering low pressure system weakens.
Additional snowfall accumulations up to a few inches are possible through Thursday, particularly over the U.P of Michigan.
Farther east, a surge of precipitation and a developing coastal low off southern New England will allow for a wintry mix to spread into northern New England tonight.
Light snowfall amounts are possible across central Maine, with freezing rain and sleet likely from the northern Adirondacks of New York State to northern Massachusetts.
Ice accretion could add up to a quarter of an inch before concluding on Thursday, which could lead to isolated power outages, as well as potentially dangerous travel conditions.
Otherwise, light snow showers are forecast to traverse the Great Lakes and into the northern/central Appalachians on Friday as the system finally begins to exit the East Coast.
For the rest of the Nation, light to moderate snow may extend into parts of the Intermountain West and central Rockies on Thursday and Friday as leftover moisture from the aforementioned atmospheric river moves inland.
Temperatures for the most part are forecast to remain near or above average outside of the northern Plains and Southwest.
Record-breaking warm minimum temperatures are expected across Florida and the Mid-Atlantic on Thursday, with anomalous warmth shifting to the southern Plains by Friday.
California officials warned the storm could be among the most impactful to hit the state in recent years leading Governor Gavin Newsom to sign a statewide emergency declaration Wednesday morning meant to hasten the state’s response.[break]
Fueled by a meteorological phenomenon known as a “bomb cyclone†churning over the Pacific, the storm was expected to lash a broad swath of California from Crescent City to Los Angeles, while potentially causing mudslides and debris flows over inland burn scars and dangerous, near-impossible travel conditions over the Sierra.
Across the Bay Area, widespread flooding and damaging winds were expected to last from Wednesday afternoon through Thursday.
“We anticipate that this may be one of the most challenging and impactful series of storms to touch down in California in the last five years,†Nancy Ward, director of the Governor’s Office of Emergency Services, said during a press conference Wednesday morning.
In early measurements, the storm was “doing exactly what we expected it to do,†said meteorologist Brian Garcia of the National Weather Service.
“This is the warm front,†Garcia added. “It was supposed to start this morning. It did — it’s going to continue through much of the a.m. hours and South Bay and southward may get a little break this afternoon, maybe even on the East Bay you might get a short little break this afternoon before the cold front [or] Pineapple Express really kind of bears down.â€
Thousands were left without power, but the region’s primary utility said it had crews standing by to clear debris and restore service as quickly as possible.
Pacific Gas & Electric had about almost 2,900 workers ready Wednesday to deal with a monster winter storm that was threatening to be among the worst in Bay Area history. ■