North-west US avoids ‘bomb cyclone’ but is deluged by ‘atmospheric river’
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A low pressure storm system known as a 'bomb cyclone' moving off the coast of the US Pacific North-west and western Canada in a composite satellite image on Nov 20.
PHOTO: REUTERS
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The north-western US avoided getting hit by a second “bomb cycle” on Nov 21 when the storm’s fury came up short of forecasts, but an ongoing “atmospheric river” deluged northern California with wind and rain.
The first bomb cyclone, in which rapidly dropping pressure produces hurricane-force winds and rain, pounded the region on Nov 18 and 19, killing two people and knocking out power to hundreds of thousands of people from Washington state to northern California.
Images of cars and houses crushed by fallen trees in Washington filled social media.
A second bomb cyclone was forecast to hit on Nov 21, but the storm’s pressure failed to drop fast enough over a 24-hour period to earn the provocative designation, said Mr Joe Wegman, a meteorologist with the National Weather Service’s Weather Prediction Centre.
Even so, the low-pressure system produced more wind and rain.
Northern California continued to be drenched by an atmospheric river on Nov 21, creating hazards on roads and flood and wind alerts.
Wind gusts of 105kmh were expected on Nov 21 evening, and risks of life-threatening flooding, and mud and rock slides remained throughout the region, the weather service warned.
About 272,000 homes and businesses remained without power in Washington and northern California on Nov 21 night, down from 600,000 on Nov 20.
The windstorm and heavy rain also damaged the power system in Canada’s Pacific coast province of British Columbia and cut power to some 225,000 customers on Nov19 night, according to provincial electricity provider BC Hydro. That was down to about 20,000 by Nov 21 evening.
The storm did bring much-needed rain as much of northern California has been experiencing abnormally dry conditions, according to the US Drought Monitor.
“It’s never ideal to have so much rain in such a short period of time, but it certainly helps to fill the reservoirs and moisten the soil,” Mr Wegman said.
About 280mm of rain fell on Nov 20 and overnight into Nov 21 in northern California, bringing snow in higher elevations, said Mr Rich Otto, a forecaster with the Weather Prediction Centre.
The storm was likely to bring another 130 to 250mm of rain, he added. AFP
