Thursday, December 3, 2009

Winter Plunges South

The first major cold front of the season pushed through Missouri yesterday morning and, behind the front, strong north winds brought winter to the Heartland. Though temperatures fell through the day, there was not enough moisture in the air to produce rain or snow.

This morning, with a bright full moon in the clear, western sky, the thermometer reads 27 degrees F. Fortunately, the winds have abated and my walk to work in the predawn darkness was pleasantly invigorating. Though cold, the air is dry, offering a welcome change from the chilly, damp weather of recent weeks.

With little solar heating at this time of year, we are at the mercy of the jet stream. Its dips (troughs) allow Canadian air to plunge southward while its northern oscillations (ridges) bring interludes of balmy weather from the south. But the tide has turned and cold spells will dominate for the next few months.