Spring, climate change, jet stream serves up buffet of wild weather hitting US

WASHINGTON: Nearly every type of wild weather hit some part of the United States on Monday as the normal changing seasons clash of cold and warm air collided with a jet stream gone crazy and a possible dash of climate change, meteorologists and scientist said.

A blizzard dumped snow by the feet around the Great Lakes. Damaging high winds - with threats of tornadoes inside - started marching across the Eastern part of the country, followed by Arctic cold. An unprecedented heat wave is poised to take hold in the Southwest. Immense amounts - more than two feet (60 centimeters) - of rain continued to fall in Hawaii. Drought persists in more than half the nation. A huge fire blazes in Nebraska with the threat of more nasty fires to come across the West.

All that tumult happened in one day in one country. About the only extreme weather missing is a hurricane and it's the wrong time of year for that, meteorologists said. Meteorologists said some of what they see on the weather maps looks more like June or July than mid-March.

Everything everywhere all at once
"We really have most types of extreme weather across the U.S. here in mid-March," said AccuWeather meteorologist and Vice President of forecast operations Dan DePodwin. But he and other meteorologists said most of the weather extremes, on their own, are not too out of the ordinary at this time - save the exception of the March heat dome building in the Southwest, which is expected to be record-shattering and more like June than March.

Having them happening together is a bit much.

"It is unusual for everything to be at the absolute extreme levels that they're experiencing right now, but it is not completely unusual in spring to see wild weather happen," said Climate Central Chief Meteorologist Bernadette Woods Placky.

The National Weather Service's warning map had to sport more than two dozen hues to catch all the types of hazards different people are facing: "This might go on the wall of an art museum; it's pretty colorful," said meteorologist Jeff Masters of Yale Climate Connections.

Spring is often wild, but this is a bit more
Spring weather is often crazy when cold and warm air collide, several meteorologists said.

"If you're going to have these types of events, it's most likely to be in February or March or maybe early April when you're starting to have a lot of clash between air masses," DePodwin said. "As that sun moves closer to the equator, you start having warmer air drawn north, so you have more frequent clashes of extreme air masses."

That triggers strong winds - March is the windiest month - and add in moisture and it triggers severe storms, DePodwin said. But it's still cold enough that winter storms can hit like they did in the Great Lakes.

A boost from climate change
The immediate cause of such extremes is a wacky shaped jet stream, which is the river of air that moves weather from west to east on a roller coaster-like path. The gentle slopes are mountainous vertical plunges and climbs, creating extreme weather at the ends, meteorologists said.

"While March is known for wild weather, this pattern is a doozy," said Jennifer Francis, a climate scientist at the Woodwell Climate Research Center on Cape Cod. "The positions of the enormous northward and southward swings in the jet stream are likely being influenced by the strong ocean heat waves in the northwest Pacific, around Baja, and along the Atlantic seaboard, which are fueled by human-caused climate change."

A study by University of Pennsylvania's Michael Mann showed such changes in planetary waves increasing in a warmer world in April to September, but he said adding in March is "a bit more speculative."

So much of what's happening is the nature of spring, when the jet stream is heading further north, where it is much of the summer, Woods Placky said.

But in Monday's mix of extreme weather some climate change fingerprints are "giving it a little extra boost," but not nearly as heavy as the heavy greenhouse gas influence on the unprecedented heat to come later this week, she said.

The downpours in Hawaii - called a Kona low pressure, which some meteorologists say is part of the jet stream wildness - is being fed by unusually warm Pacific waters, Woods Placky said.

The most unusual is yet to come: Triple digit heat

Masters, Woods Placky, Mann and DePodwin all said the biggest and wildest weather is coming in a day or two, when a strong high pressure or heat dome parks on the Southwest.

Phoenix has only once had a March day that hit 100 (37 Celsius) and it doesn't usually start seeing 100 degree days till May, but forecasts are for five straight days of triple digit temperatures flirting around 107 (41 Celsius) or higher, meteorologists forecast. The United States hottest March day on record was 108 (42.2 Celsius), set in Rio Grande City, Texas, in 1954. There's a good chance it may be tied or broken, they said.

One weather service forecaster typed in a weather forecast discussion "I audibly gasped" when he looked at forecast temperatures coming out of a computer model.

This will be the type of unusual event that's studied for years to come like the 2021 Pacific Northwest heat wave, Yale Climate Connections' Masters said.

This is the type of extreme heat "that you could not get without human-caused climate change," Masters said. "The extremity is so ridiculous that 50 years ago you would not have seen it."

Between the heat and a country that's more than half in drought, Masters said he worries about fires like the one blazing in Nebraska at record levels.

"We're going to see an early and severe fire season out West," Masters said.