The oppressive heat pummeling large portions of the Eastern U.S. this week is all kinds of wrong, with the heat index on Thursday topping 100 degrees Fahrenheit in Washington D.C., Baltimore, and John F. Kennedy International Airport in New York. And here's one more thing to hold against it: the heat is going the wrong way. 

As the Associated Press explains, weather systems in the U.S. usually travel west to east. The system that's bringing us the current heat wave, however, has been moving east to west starting some time last week. Essentially, as the National Weather Service explained earlier this week to the Press of Atlantic City, this means that a "dome of hot air" has been beating up the east coast without the promise of a normal change-up in air masses. With everything going backwards, the hot air just keeps coming. In other words: the backwards movement is keeping the heat in place, and for longer. "It's definitely unusual and going the wrong way," National Weather Service operations chief Jon Gottschalck told the AP, adding, "this is pretty rare."

We can, apparently, blame a cooler weather system for starting the backwards trend with the weather, the AP says: 

Just before the high pressure moved east to west, a rainy and cooler low pressure system moved from the Mid-Atlantic to Texas, he said. That storm system broke off the jet stream, which is parked up in Canada, and made the U-turn first.

That's supposed to change in the next few days, however, once the system starts moving normally again. So maybe everything won't be horrible starting some time this weekend. That'll be good news for the 141 million people living in areas of the country currently under a heat advisory, including the New York Philharmonic fans who complained Tuesday night after the orchestra cut their outdoor concert short thanks to the unbearable heat.