Polar air to bring October-like chill to 250 million in central, eastern US

Fall weather lovers, make ready! A major outbreak of cold air will unfold next week, bringing temperatures more typical of mid- to late October across much of the central and eastern United States, AccuWeather meteorologists say.

At least three-quarters of the population east of the Rockies will experience the chill at some point next week. The main areas likely to avoid it include much of the Florida Peninsula, portions of the immediate Atlantic coast and central and South Texas.

Even cool-hardy residents of the Midwest and Northeast who resisted earlier cool waves may reach for long sleeves and jackets next week. In the South, some may welcome the cooler air, while others may notice the chill, especially at night.

A large buckle in the jet stream will push southward toward the Great Lakes region. Daytime highs are likely to run 10-20 degrees Fahrenheit below historical averages. In cloudy, rainy locations, temperatures could dip as much as 30 degrees below normal.

If this occurred in midwinter, it could produce widespread single-digit to below-zero temperatures and bands of heavy lake-effect snow. However, with warmer land and lake waters and stronger late-summer sun, temperatures will remain much higher.

On the chilliest days, highs in the northern tier of the Midwest and higher elevations of the Appalachians may hold in the 40s. Farther south and east, highs will range from the 50s and 60s across the central Plains and Ohio Valley to the 70s and low 80s from the southern Plains to the central Gulf Coast, accompanied by some of the lowest humidity levels since last fall or winter.

Overnight lows in parts of the Midwest and interior Northeast will fall into the 40s and even the 30s. From the southern Plains to the interior Southeast, some nights will dip into the 50s and even the 40s.

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Along the Atlantic coast, the arrival of cooler, less humid air may be delayed until late this week. A storm tracking from southwest to northeast could precede it with drenching rain or some shower activity.

Instead of producing snow flurries and squalls, this pattern will bring clouds and chilly showers, possibly mixed with small pellets of soft hail known as graupel.

Warm Great Lakes waters combined with incoming cold air may create conditions favorable for waterspouts. Gusty winds will also build waves, creating hazardous conditions for small craft.

Breezes or cloud cover will likely prevent a widespread frost or freeze at night; however, exceptions are possible where the sky clears and winds calm for several hours, especially from the Plains to the Midwest and interior Northeast.

By next weekend, the jet stream is likely to lift northward, while an area of high pressure may expand over the Eastern states. If that occurs, many of the same areas experiencing the chill could shift back to a midsummerlike pattern with higher humidity and highs in the 80s to near 90 for a few days.

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