In the Northern Hemisphere, as storm systems track from west to east, the winds around their center of low pressure move counterclockwise. Ahead of the storm, southerly winds pump warm, humid air into the system, triggering showers and thunderstorms as the cold front approaches. North of the storm's center, this moisture is pulled into cold air behind the front, producing cool rain or snow, depending on the temperature of that air. If the storm is especially strong, determined by the depth of its central pressure, the circulating winds can be fierce and, when combined with snowfall, may produce blizzard conditions on the north and west sides of the system.
The current winter storm, centered over Lake Michigan this morning, is very potent. Its vanguard of showers and mild air flowed across Missouri on Friday, extending into Saturday morning; by Saturday afternoon, cold air was filtering in from the north and, by last evening, snow showers mixed with a gusty northwest wind. The strong winds and snowfall increased through the night, producing blizzards of horizontal snow and pulsations of wind that roared through the barren trees. By morning, we had 4 inches of fresh powder, blown clear in some areas and piled into deeper drifts in others.
It is now almost noon; the storm has moved to the east, the winds have died down and a snowy landscape reflects a bright southern sun; the temperature sits at 18 degrees F. Travel will be slow and shoveling will be necessary but we have survived another round of nature's fury.
