We are rounding a meteorological corner as we head into the month of December. In the weather world, November 30th represents the final day of autumn and the last day of Hurricane Season. December 1st marks the official beginning of winter. While it won't be all that winter-like (by Oklahoma standards) to start the season, I can assure you some real winter weather will be fast approaching within the week.
A quick look back at our fall months show near-normal temperatures for an overall average although November was several degrees cooler than normal. Each month had below-normal rainfall, adding to the 7"+ rainfall deficit for the year in Tulsa. Severe weather was minimal while the most recent cold spell allowed for a taste of winter with the first snowflakes recorded for the season. And now, the season is going out quietly – a big blessing for all travelers in our region here at the end of the holiday weekend.
Heading into the first several days of December, you can expect a gradual warm-up as southerly winds kick in at the surface and no large storm systems to bring cold air to the state. The coolest day in the near-term will actually be Sunday in the wake of a very weak cold front. High temperatures may be just under 60, still a good 5°+ above normal. Some morning fog may also inhibit warming just a bit.
Temperatures will likely peak on Wednesday as a warm nose of air surges into the state ahead of a strong Arctic cold front. This large storm system evolving over the west in the week to come will set the stage for an abrupt and large change to the weather. Our temperatures will take a cliff-fall and hover near or below freezing from Thursday into the weekend. The orientation of the jet stream (as shown in the graphic) is such that several waves of energy may ride over the cold air mass, spawning precipitation. One or more rounds of wintry precipitation may occur late in the week depending on upper-level energy. With an initially shallow cold air mass in place, we may see precipitation begin as freezing rain or sleet. As the cold air deepens, some snow is also possible. Either way, this is the first time this season I feel comfortable enough six days out to mention this kind of threat.
The moral of this little blog post? Enjoy the warmth while it's here! After Wednesday, we're on track to get a healthy and prolonged dose of winter. It'll be a week of extremes, from unseasonable warmth to bitter cold. Keep the coats on hand and watch that forecast closely! Be sure to follow me on Twitter: @GroganontheGO, and like my page on Facebook!