The Winter That Hasn’t Been Still Isn’t….February 17th, 2012 at 10:40 pm by Don Paul under 4 Warn Weather
Still no signs whatsover of a fundamental pattern change across North America which would allow any lengthy periods of wintrier weather to develop. With a waning la nina and a continuing active phase of an oscillating pattern far, far to the west of our continent (the Madden-Julian Oscillation), conditions will remain favorable for a westerly flow from the Pacific to the Atlantic. This flow will buckle from time to time, allowing brief arctic intrusions and active storm systems to pass near the Great Lakes. But longer-lasting tie-ins in the northern branch of the jetstream with arctic air are unlikely to develop over the next couple of weeks. In addition, the absence of snow cover over much of North America at the mid-latitudes doesn’t allow for airmasses to become as cold as they ordinarily would in mid-winter, and even at high latitudes the temperatures are above average over North America.
While March is frequently an active, stormy month due to the battle between springlike subtropical air from the Gulf and arctic air from the north, the battlefield looks a little less fertile than usual as we move through the 2nd half of February. By no means is Spring at our doorstep, and there will still be some wintry outbreaks, but the chances for a real “flip-flop” to a truly wintry pattern are growing slimmer–as many of you have already figured out.