Blast of cold engulfs eastern US as summer heat swells in west
More than 100 million Americans in the Midwest, Mid-South and Mid-Atlantic are under frost and frost alerts signifying an outbreak of early-season cold air that will end the growing season. Freeze warnings, which include all of Arkansas and Tennessee, were extended to the Gulf Coasts of Mississippi and Alabama to account for lows in the 1930s on Tuesday night.
Dozens of record lows were set from Minnesota to Texas on Tuesday morning, with temperatures dipping into the 20s and 20s. Des Moines, Omaha and Kansas City were among the places that set record highs.
Over the Great Lakes, meanwhile, lake-effect snows delivered a first dose of the worst winters. A full-fledged blizzard – originating in the waters of Lake Superior – buries parts of Michigan’s Upper Peninsula, with additional snows emanating from Lakes Erie and Ontario.
Nearly 30,000 power outages were reported across the Upper Peninsula as double-digit snowfall and high winds snapped tree branches and power lines.
Snowflakes were also spotted in Chicago on Monday, while Madison, Wisconsin, posted its first measurable snowfall in 32 years with a light dusting.
On the West Coast, by contrast, the start of the workweek saw highs in the 1980s and 1990s. A spate of wildfires erupted amid the brief warm-up, with air quality concerns becoming a problem as smoke billows over Oregon and Washington.
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Things are about to change in a big way, though – the atmosphere is about to shift 180 degrees. A wet and cold fall will head for the northwestern United States by the end of this week, as the core of unusual heat expands to the east. It’s a classic example of the whim of the atmosphere, with roller coaster changes in store.
The incentive for dynamic contrast is a highly amplified, or wavy, jet stream. It rises northward over the western United States, allowing ridges to form or high pressure to build. This diverts the weather to Canada.
In the East, it’s a different story. A bowling ball upper level low — or a pocket of high-altitude, low-pressure, spinning cold air nestled in a dip in the jet stream — is stationed over the Great Lakes. It is progressing slowly in Ontario. Freezing air pours south in this plunge of the jet stream, with freezing temperatures all the way to the Gulf Coast.
Aft of the low, northerly winds passing over the warm waters of the Great Lakes cause lake-effect snowfall as well as waves are expected to reach up to 25 feet on Lake Superior on Tuesday.
On Tuesday morning, record temperatures were recorded from the upper Midwest to the south-central. Des Moines plunged to 21 degrees Tuesday morning, setting a record for the day and representing the coldest weather to start the season since 1987. Kansas City, Mo., also broke a morning record 25 degrees, and Omaha has reached a record high. at 16 degrees, the coldest on record at the start of the season. Kansas City’s morning temperature would have been averagely low for December 12.
Wind chill in Minnesota went below zero Tuesday morning.
The heart of the cold is moving east.
In the East, high temperatures in the 40s and 50s will be common Tuesday and Wednesday. The forecast high for Chicago is around 43 degrees on Tuesday and 48 degrees on Wednesday, compared to an average high of around 62 degrees in mid-October. Highs in Detroit are expected to hover between the mid-40s and Wednesday, with rain showers; the average there is also in the low to mid-60s.
Columbus, Ohio would normally be around 65 degrees; Tuesday and Wednesday it will be close to 45 degrees. And in Nashville; Washington D.C.; Philadelphia Cream; and New York is the same – highs in the 50s through Wednesday.
Wednesday and Thursday morning lows will be in the 20s and 30s across most of the eastern half of the country.
To the west, temperatures are rising. Calgary, Alta., jumped to 77.4 degrees on Monday, breaking the previous high of 75.9 degrees. According to Kyle Britain, meteorologist at the Weather Network, that’s a degree or two warmer than the average high temperature on July 16.
Seattle experienced an equally extreme anomaly. On Sunday, the city reached 88 degrees, the second hottest October day on record in nearly 130 years of observation, and the hottest day ever recorded at the end of the season. It was 21 degrees cooler on Monday, peaking at 67 degrees, but still warmer than normal – it turned out to be the fifth hottest October 17 in 78 years.
The hot, dry weather has allowed a number of wildfires to break out, pouring smoke into the skies over the Pacific Northwest. Now Seattle, Tacoma and Olympia in Washington and Portland, Oregon are on air quality alerts.
“Everyone, especially sensitive groups, should limit time spent outdoors, avoid strenuous outdoor activity, and choose light indoor activities,” the National Weather Service warned. Smoke conditions should ease by Friday.
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Like a seesaw, the heat and the cold will swap places in the contiguous United States. The jet stream will completely reverse its positioning, swinging a strong cold front across the northwest on Friday as warm high pressure builds in the east.
“Mountainous regions will experience the first snowflakes of the season,” wrote the National Weather Service in Portland. “Snow levels will drop between 3,000 and 4,000 feet from Saturday evening through Sunday morning.”
In the eastern half of the country, highs of the 70s will return, including in some places that have recently seen snow. It looks like the sweetness will persist for much of next week.