‘Pineapple express’ storms bring strong winds and flash flood risk to California
The first in a series of back-to-back atmospheric rivers arrived in California on Wednesday, as forecasters warn the severe storms will batter the state with heavy downpours, strong gusty winds and risks of flash floods.
Both “pineapple express” atmospheric river systems – which pull streams of moisture from the Pacific near the Hawaiian islands before making landfall along the west coast – have the potential to wreak havoc, especially in vulnerable areas where past wildfires have left burn scars, or where the landscape has already been saturated by previous rains. The storms will also dump heavy snow over the Sierra and intermountain west region and churn up high surf along the coasts.
“This system has the potential to bring a six- to 12-hour period of heavy to locally very heavy rainfall in NorCal on Wednesday,” said the climate scientist Daniel Swain in a discussion of the storm posted on Tuesday, warning that widespread roadway and small-stream flooding is likely.
Officials across the state readied resources on Tuesday ahead of the storms’ arrival, and urged residents to prepare for power outages, downed trees and hazardous road conditions through the week. The state’s governor, Gavin Newsom, activated the state operations center and the flood operations center to coordinate emergency responses across affected areas, and pre-positioned personnel and equipment in communities most at risk.
“The state is working around the clock with our local partners to deploy life-saving equipment and resources statewide,” Newsom said in a press statement.
The storm rolled into California’s far north first before moving down the coast. Dark clouds gathered over the San Francisco Bay area on Wednesday morning, with rain arriving by the afternoon.
Much of the first storm’s heaviest downpours and mountain snow was due to arrive late on Wednesday and overnight into Thursday. Forecasters expect an even more powerful storm to follow it on Sunday.
The storms have put residents on edge. Last winter, California was battered by a string of atmospheric rivers that unleashed extraordinary amounts of rain, causing flooding and waves that hammered shoreline communities, as well as extraordinary snowfall that crushed buildings. More than 20 people were killed by the historic weather.
The memory was in mind in Capitola, along Monterey Bay, as Joshua Whitby brought in sandbags and considered boarding up the restaurant Zelda’s on the Beach, where he is kitchen manager.
“There’s absolutely always a little bit of PTSD going on with this just because of how much damage we did take last year,” Whitby said.
Even though Wednesday’s storm could deliver some damaging impacts, the stronger system is expected later into the week. “All of the ingredients,” Swain said, “will be in place for a potentially very high-impact storm on Sunday-Monday.” Noting that the details are still uncertain, he added that heavy, widespread precipitation and damaging winds are likely in store for southern California.
While the storms would be intense on their own, the biggest problems could be posed by their cumulative impact, especially in areas already saturated from previous downpours. Communities in San Diego and Ventura counties are still grappling with the aftermath of serious flooding this winter and both areas are going to see significant rainfall this week.
Along with potentially damaging rains and winds, forecasters said the storms could dump a fresh layer of snow in the mountains, a promising sign for the meager snowpack that’s now just 52% of average. The second snow survey of the year, conducted Tuesday, showed a big improvement from last month, which stood at just 28% of average. Snow is a critical part of California’s water supply, acting as a kind of water savings account for the year ahead.
“Even though the storms during January slightly helped out our snowpack, we’re only about halfway of where we should be for this time of year,” said Sean de Guzman, the flood operations manager for the department of water resources.