While back-to-back systems for the region seem a bit like a record lately, the phenomenon is really significant.
Rivers in the sky resulted in landslides blocking roads, rivers flooding cities and, in one case, sending an old lake bed back into a lake.
British Columbia typically experiences atmospheric riverine events in November, as does the Pacific Northwest. The problem for both regions this year has been the consistency of the systems, with no downtime for drying between the two.
“The first atmospheric river event hit us hard from November 13 to 16, and it dumped a lot, 150 to 300 mm (about 6 to 11 inches), of precipitation in less than 48 hours,” said Johnson Zhong, meteorologist at Environment Canada. noted.
“There was up to 30-50 cm (1-1.5 feet) of fresh snow at 1,500-2500 meters (5,000-8,000 feet) above sea level,” he observed. “One of our atmospheric river events rained much higher than 2,500 meters, so the rain melted the snow and helped create the floods. ”
One of the areas most affected by the flooding was the Sumas area, about 50 miles east of Vancouver.
“A hundred years ago there was a Sumas Lake. Then they pumped the water to make good farmland. It’s been farmland for 100 years, and now it’s a lake again, ”Zhong explained.
He added that more than half of Vancouver’s egg and dairy supply came from this farmland, which has exceptionally hit the region.
The unprecedented amount of rain created major flooding, sweeping away bridges and roads, completely cutting off many other small Canadian towns from the rest of the world.
Merritt, British Columbia, is one such city.
“Merritt is a city of 7,000 people and is totally inundated,” Zhong said. “This town is in an area that doesn’t get a lot of rain. But with the combination of rain and snowmelt, the whole city was flooded. The water and sewage system broke and the whole town had to be evacuated. “
British Columbia has suffered a lot since the summer months.
They suffered a relentless heat wave that swept across the region and killed nearly 600 people.
They also experienced wildfires that wiped the town of Lytton completely off the map.
New burn scars from the forest fires also worsen the potential for flooding and mudslides, Zhong said.
Mudslides and landslides are a major concern for both British Columbia and Washington State.
“Persistent rains in recent weeks have dramatically increased soil moisture to high levels in western Washington,” the National Weather Service (NWS) office in Seattle reported. “Heavy precipitation of an additional 1 to 3 inches in the mountains and up to 1.5 inches in the plains has fallen in the past 24 hours. Therefore, the increased threat of landslides will continue until today despite the end of the heaviest rainfall. “
In the Seattle area, which is also soggy, they’re hoping all the rain doesn’t come at once.
Seattle is experiencing its wettest fall on record. Seattle-Tacoma Airport recorded 18.91 inches of rain from September through November, with more on the way.
By Tuesday, the month could end as one of the wettest November on record. With an additional 2-3 inches of rain expected to fall, more flooding is inevitable.
“The big factor that will affect the extent of the expected impacts will be the amount of break we receive in areas where river flooding continues today,” the NWS in Seattle noted.
The Nooksack and Skagit rivers north of Seattle continue to rise and have not yet reached their peak, so more precipitation in addition to already swollen rivers could create major flooding problems for neighboring towns.
“It is still unclear how the rivers in these areas will react to the additional precipitation over the next 2 days,” added the NWS Seattle.
Climate impact on atmospheric rivers
Marty Ralph, director of the Center for Western Weather and Water Extremes at the Scripps Institution of Oceanography in San Diego, said the climate crisis could intensify atmospheric rivers in the West.
“Warmer air temperatures, in general, will mean freezing levels are higher than they have been in the past,” Ralph told CNN. “But as storms vary, even without climate change and some can be very hot, just by the natural situation, it is clear that background warming is expected to increase the temperature. [freezing] levels. “
Ralph explained that a higher level of freezing, the altitude at which rain turns to snow, can be dangerous with a wet landscape and full rivers.
“It gives additional potential power on impact,” he said. “The rivers are already high again, so this one is going to take a big hit. “
Warmer air can also contain more water vapor, which feeds atmospheric rivers. Ralph noted that as the atmosphere warms due to climate change, the intensity of storms will likely increase and become more dangerous.
“As a scientist, my role is to help raise awareness that the situation looks like a strong to extreme situation. [atmospheric river], and the implications of that are for additional heavy rains and – given the situation on earth – flooding, ”he said. for me this is a pretty serious situation. “
Hurricane season review
The last day of Atlantic hurricane season is tomorrow, and that was one of the records.
With 21 named storms, this was only the third year that the seasonal rotating list of names has sold out.
An additional new list of hurricane names has been enacted, never-before-seen images of a major hurricane have been recorded from ocean level, and billions of dollars in damage have been left behind.
Our full summary of the 2021 Atlantic hurricane season will be released on Tuesday morning, and you can find it here.
Snow lake effect
Another episode of lake-effect snow will affect parts of the Great Lakes this week.
“Snowfall totals will be lower than the previous system, but downwind areas of the Great Lakes may receive higher amounts due to the enhanced lake effect,” said the Weather Prediction Center. .
With a lake freeze percentage of less than 2%, the lake effect snow machine is officially “on”.
Most areas that receive snow will not see very high totals. Most of the snow this week will remain under three inches.
However, in parts of Michigan this could create some travel issues. The NWS office in Grand Rapids has issued a winter weather advisory, with heavy snowfall expected during the evening drive. Up to three inches of snow could fall in less than four hours.
“Impacts on roads may be small at first given temperatures initially above freezing, but we should start to see slippery roads developing after dark,” the NWS office in Grand Rapids said. .
The snow is expected to end by Tuesday and drier conditions will follow over the next few days.
California fire threat persists
A high fire threat remains for much of southern California for most of the week.
Winds around the Los Angeles area will sometimes be up to 45 mph and humidity levels are between 5 and 15%. Dry and hot conditions will increase the risk of fire throughout the week.
“Rapid growth of fires is possible if a fire breaks out. Be extremely careful with potential sources of fire ignition and be prepared to evacuate quickly if a wildfire develops nearby, ”the NWS Los Angeles office urged.
Last week’s Santa Ana wind event brought winds of nearly 90 mph in some locations and caused power outages to more than 70,000 homes and businesses.
While the threat of wind this week is not as intense as it was last week, the threat of fire remains and fires could easily ignite.
Real vs fake Christmas trees
As the holidays are in full swing and millions of people put out Christmas lights, precious ornaments and choose the perfect Christmas tree. Are you someone who prefers a real tree or a fake? Is it better to cut down a fresh tree every year or buy a plastic one from the store that will be used for years to come?
CNN Rachel Ramirez did some research to find out.
Cheers! England’s tallest pub spilled pints and fed patrons, after dozens of travelers were stranded for days. A major winter storm brought 90mph winds and snowdrifts which trapped patrons at the pub. To some, it may have seemed like a dream come true. The pub has fed the temporary residents well and no one has been thirsty as the beer continues to flow.
CNN meteorologist Haley Brink and Rachel Ramirez contributed to this weather column.