The month of March is notorious for wild weather, but this is a little ridiculous. The United States is facing four colliding extreme events that will unleash a range of hazards across the country this week—from dangerous fire weather to heightened tornado risk and blizzard conditions.
According to the National Weather Service, an unseasonable heat dome is intensifying over the West, ushering in temperatures that are more akin to peak summer than early spring. The NWS expects multiple temperature records to break across the region over the next couple of days. Meanwhile, it’s winter again in the East. An Arctic blast will send temperatures plunging below freezing as far south as Florida while a powerful blizzard dumps heavy snow over the upper Midwest and Great Lakes. Oh, and severe thunderstorms are encroaching on the East Coast, threatening the Mid-Atlantic with destructive hurricane-force winds, large hail, and potential tornadoes. Did you get all that?
Understandably, the NWS map of public alerts was awash with color Monday morning. Forecasters have issued various weather warnings from Hawaii to Maine, the majority of which are concentrated in the East as the blizzard and thunderstorms create dangerous storm conditions.
Unusual jet stream behavior underlies this confluence of extreme weather events. The jet stream is a river of air that flows west to east around the globe, separating cold Arctic air in the north from warmer tropical air in the south. It often meanders, but right now, it’s plunging dramatically over North America, “which means you get a lot of extremes next to each other,” former National Oceanic and Atmospheric Administration chief scientist Ryan Maue told the Associated Press.
When the jet stream bends into large vertical waves like this, it creates ridges and troughs that can produce starkly different weather for different parts of the country. A ridge is a large area of above-normal atmospheric pressure that pushes the jet stream northward of its usual position and ushers in warm air. A trough is a low-pressure area that allows the jet stream to dip southward and bring Arctic air with it, according to NOAA.
A gradually intensifying upper ridge is driving the unusually early heat dome affecting the western U.S. this week, while a trough is causing the Arctic blast in the East. Meanwhile, storm fronts coming from the Pacific have been pushed north by the high-pressure heat dome, allowing them to “grab access to that cold air reservoir up there” and bring it back down south on the other side of the ridge, Maue explained.
NWS forecasters expect the heat dome to break or tie record highs across parts of Southern California, the Desert Southwest, and into the Great Basin over the next couple of days. “These temperatures will serve as a baseline for even more anomalous, more widespread record-breaking heat expected later this week,” the agency stated Monday morning.
The NWS has issued extreme heat watches across southeastern California and southern Arizona, where temperatures could climb above 100 degrees Fahrenheit (38 degrees Celsius) by the latter half of the week. But the heat dome will encompass most of the western half of the country, expanding into the Great Plains.
There, high winds on the backside of the blizzard are combining with the unseasonable dry heat to create fire weather in southeastern Wyoming, northeastern Colorado, western Nebraska, west-central Oklahoma, northwestern Texas, and much of the Gulf Coast.
By Friday, the NWS expects 36.4 million people across California, southern Nevada, and southeastern Arizona to be at moderate (level 2 out of 4) heat risk. This can adversely affect those who are sensitive to heat, especially those without access to proper cooling and hydration. It can also impact some health systems and industries.
Meanwhile, an intense cyclone is tracking across the Great Lakes and has already dumped up to 2 feet (0.6 meters) of snow across an area stretching from northeastern Wisconsin to portions of northern Michigan, the NWS said Monday morning.
“Although the heaviest snowfall rates should have exited the area early this morning, additional heavy snowfall of 12 to locally 20 inches [30 to locally 51 centimeters] can be expected in upper Michigan today as the center of the cyclone passes just to the southeast,” the agency added. Strong, gusty winds wrapping around the cyclone could prolong blizzard conditions in this area today before the center of the cyclone moves into Canada this evening.
As of 10:20 a.m. ET on Monday, more than 117,000 customers had lost power in Michigan, according to PowerOutage.us, and another 12,500 in Wisconsin. The combination of outages and below-freezing temperatures can create a dangerous situation for anyone suddenly unable to heat their home.
As the cyclone treks across the Great Lakes, a potent cold front will sweep from across the East. “The combination of the vigorous dynamics ahead of the potent front and the maximum daytime heating will be ripe for the eruption of severe weather, especially across the interior Mid-Atlantic late Monday afternoon into early evening,” the NWS stated.
The Storm Prediction Center has issued a “moderate risk” of severe thunderstorms for this region, affecting more than 12 million people. These fast-moving storms may become widespread and be accompanied by damaging wind gusts and tornadoes.
“Strong tornadoes will be possible—especially from [Maryland] southward where the greatest low-level moisture will be present,” the SPC stated.
Then, it’s going to get really cold in the South. The Arctic blast will bring a drastic end to the recent warm spell as below-freezing wind chills penetrate down to the Gulf Coast and the Florida Panhandle by Tuesday morning, according to the NWS. Freeze warnings are in effect for the Arklatex region and portions of the southwest. Farther north, rain following behind the potent cold front could change over to snow, with accumulations of over 6 inches (15 centimeters) possible in the central Appalachians of West Virginia.
So, March is certainly living up to its reputation for significant weather swings. The outlook could change as these volatile conditions develop over the course of the week, so be sure to keep an eye on your local forecast for the latest updates.
Source: Gizmodo