Michael Grogan's Weather Blog: Indian Summer Prevails Ahead of Next Storm System

Unseasonable warmth has taken over much of the United States this week with temperatures running between 10° and 20° above normal here in Oklahoma. While mild spells with 60s and even 70° readings aren’t all that unusual here, the length of this one is.  Tulsa will experience a solid week of temperatures over 60°… seven consecutive days at least 10° above normal. Warm weather lovers have got to love this bonus warmth at the time of the year when an average HIGH temperature is 50°.  Tulsa’s temperatures may not even drop that low Friday and Saturday mornings!

Those who pay close attention to weather in Oklahoma know that unseasonable warmth like this in the cold season usually precedes a big storm system. Well, that storm system is on the Radar, so to speak, and will arrive with colder air by later this weekend. Our weather pattern remains largely unchanged through Thursday with cool nights and very mild days. The attached map displays the temperature anomalies across the central U.S. late Thursday showing temperatures running 10° to 25° above normal for nearly all locations!  By Friday, south winds start to really howl and temperatures will crest in the lower 70s by the afternoon, nearing record highs for our region.  Gulf moisture will also be funneled north into our region, setting the stage for a wet and potentially stormy Saturday as the cold front enters Oklahoma.

We don’t often talk about severe weather in December, but the incoming system will tap into the warmth and increased moisture (which are usually lacking by this point in the season) to spark some storms in the area. It’s a weather pattern more often seen in April, but if the ingredients are in place, then the threat is there. The Storm Prediction Center already has outlined a risk area from the southern half of Oklahoma into eastern Texas for severe thunderstorms. The timing of this system isn’t nailed down yet, but it is trending slower, which puts our highest rain chances Saturday afternoon and evening. That doesn’t bode well for the Tulsa Christmas Parade, but at least we won’t have treacherous or brutally cold wintry weather!

The cold air arriving on Sunday behind this system isn’t of true Arctic origins. We’ll see chilly conditions, but in reality, our temperatures will be settling down back to a more normal level for this time of year.  The following week won’t be nearly as warm, but no major signs of Arctic air are apparent out to the start of Christmas week.  The El Niño pattern often keeps the polar jet stream locked in a more west-to-easterly flow, locking up that bitter cold air well to the north. However, more storm systems will be lined up behind this one so precipitation chances will likely be on the rise into mid-December. It’s too early to prognosticate about Christmas yet, but I would step out and say the chances of a White Christmas are lower this year. For one, our temperatures need to be below freezing. That is certainly not commonplace yet and if this pattern holds, our first snow will be put on hold until much later in the winter than normal.

I’ll hold off on any more winter weather talk… I’m sure there will be plenty of that as the winter goes along.  Enjoy this warmth while we have it! For more updates on our weekend storm system, follow me on Twitter: @GroganontheGO and on my Facebook page.