Get Your Weather Geek On

By Margaret Lyons in News on Sep 23, 2004 3:12PM

Yesterday was the autumnal equinox, so it's officially autumn. Rock. But maybe you noticed that it doesn't feel like autumn, even if it's starting to look like it. Chicagoland trees have started shedding their leaves early this year after an unusually stressful spring.

Trees do their growing in April, which was extremely dry this year, so the trees didn't develop normally. Then May was especially rainy (phew, wasn't just our imagination), so the trees' roots grew upwards, which is the wrong direction. Then came a dry June and the poor bastards didn't know what to do, so now the trees are nutrient-deprived and are shedding their leaves to conserve energy. Man, oh man, it is tough times all around. Might you enjoy a helpful graphic that explains our abnormal summer weather? Yes, please.

And now, for the most interesting and informative few paragraphs we've read in weeks:

In a normal summer, the sun heats North America like a griddle, which in turn warms the air above it. Where high altitude jet streams draw cold Canadian air all winter long, rising warm air in spring and summer soon climbs to break it apart.

When the jet stream can't push cold air south, warm southern air forces its way up the middle of the continent.

But this year, unnaturally thick ice in Hudson Bay so chilled the sky above it that a low pressure system formed over Quebec--then hovered for weeks. As the weather system churned, it pulled cold, brittle air out of the north and hurled it down the Great Lakes.

A little more than two weeks ago, the pattern finally was broken by high pressure stacking up over the Ohio River Valley. Air is rolling clockwise around the system, sucking warm air from the Gulf of Mexico, spitting it at Chicago in a warm south wind.

Sweet lord, there was a reason?! Ask Tom Why has let us down in the "explain the weather" department. We wish we had learned this information earlier in the summer so when people tried to make small talk by saying, "Why is it so freaking cold?", we could have thrown down, "Well, the sun heats North America like a griddle…." Booyakasha.