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Cool Summer: Jet Stream Dip Sends Temps Plunging and Beats Records

Forecasters say a dip in the jet stream will keep it cool all week in the East.

A big summer cooldown sent parts of the South to their coldest temperatures on record for July and gave the Northeast such a taste of fall that it was only a few degrees above freezing in some places.

Montgomery, Alabama, hit 59 degrees on Wednesday morning, tying its lowest reading on record for the month. Knoxville, Tennessee, hit 55, beating a 140-year record for the date. And the mercury in Saranac Lake, New York, dipped to 37. The catalyst was a southward dip in the upper-air pattern known as the jet stream. Forecasters said high temperatures would be as much as 25 degrees below normal on Wednesday. They said the jet stream would push even farther south in the next few days, making for a cool week throughout the East. The same weather pattern made the first half of 2014 the coldest January-to-June period in the Lower 48 states in 21 years, says the National Climatic Data Center.



— Erin McClam