Cold air returns to Midwest, Northeast with frost risk; South faces record-challenging chill
A surge of chilly air will spread across much of the central and eastern United States, bringing frost risk to some northern areas and unusually cool, conditions that could challenge records in parts of the South.
Bernie Rayno breaks down the timing on when and where the cooler air will set up.
A new batch of cold air settling into the Midwest and Northeast later this week into the weekend will bring the potential for frost and freezes in areas that were affected last week, as well as places that avoided damage.
There are some key differences in the setup this time compared to last week that may limit the potential for damage, including the cold not being as concentrated on a small area of the country.
Still, people across much of the central and eastern United States will be reaching for jackets, fleece and long-sleeved shirts from late this week through the weekend, a shift from the chill that was largely confined to the Northeast last week.
A jacket may be needed for those heading to Louisville, Kentucky, on Saturday for the horse race. Rain is forecast to hold off.
This setup will bring unusually chilly days to the south-central and southeastern U.S. due to thick clouds and periods of rain. While the rain will be much needed to ease drought and wildfire concerns, people expecting typical early-May warmth will be in for a shock.
"Some record low maximum temperatures may be set in the Southern states, with highs in the 40s and 50s F in some locations, compared to historical averages in the 70s to near 80," AccuWeather Meteorologist Brandon Buckingham said. "That's 20 to 30 degrees below average."
"Temperatures, especially daytime highs in the Midwest and Northeast, will run several to 10 degrees below average this time, compared to 15 to 30 degrees below average last week," AccuWeather Senior Meteorologist Bob Larson said. "New York City will see multiple days with highs in the upper 50s, compared to typical highs in the 60s. Last week, there were multiple days with highs in the low to mid-50s."
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In the Northeast and Upper Midwest, last week's prolonged periods of below-freezing nighttime temperatures were caused by air originating in northern Canada, combined with light winds and a clear sky — ideal conditions for temperatures to plunge into the 20s and teens.
The chill arriving late this week will be driven by a large storm in the jet stream, rather than a sprawling area of Arctic high pressure. Systems like this tend to produce breezes and areas of low clouds that can linger after dark. The breeze helps prevent the coldest air from settling near the ground, while cloud cover acts like a blanket, limiting how much heat escapes.
Because of the clouds and breeze, temperatures may hover just above freezing at night or dip below the mark only briefly, Larson explained.
There will be the risk of spotty frost in the normally colder outlying areas outside of the pink zone on the map. Low-temperature forecasts are for approximately 6 feet above ground. Temperatures near the ground, away from paved surfaces, can be 5-10 degrees Fahrenheit lower than the forecast low when the sky is clear and calm all night.
"There will be pockets of frost in the Upper Midwest at the start of the weekend, spreading to the Ohio Valley and central Appalachians late in the weekend into early next week," Larson said.
There will be the risk of spotty frost in the normally colder outlying areas outside of the pink zone on the map. Low-temperature forecasts are for approximately 6 feet above ground. Temperatures near the ground, away from paved surfaces, can be 5-10 degrees Fahrenheit lower than the forecast low when the sky is clear and calm all night.
Last week, a hard freeze reached as far south as Maryland, Virginia, Delaware and New Jersey. Prolonged freezing temperatures can cause extensive damage to budding plants, blossoms and tender spring growth on ornamental shrubs, as well as vines, berry bushes and fruit trees.
"One key difference this time is that the duration of frost or freezing temperatures will be much shorter than last week," AccuWeather Senior Meteorologist Brett Anderson said.
There will be some exceptions, especially when the sky clears and the winds calm.
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