Wednesday, December 16, 2015

December-like weather (for a minute) and our first look at Christmas week

Warm December weather continued into early this week, despite a cold front over the weekend. High pressure behind that front was Pacific in origin, so it didn't bring a great deal of cold air. Hence we stayed in the 60s for highs (actually 70° officially yesterday).

Today, another cold front moves through and this one will bring some more December-like air with it. Ahead of the front, showers and even a few strokes of lightning occurred and moved over the metro this morning. Expect to see a chance of showers continue this afternoon until the front passes by rush hour. The strongest storms with this system will be closer to the Gulf of Mexico today.

Behind today's front, our 60°+ highs will be gone for several days. In fact, the high pressure system that builds into the region will have some pretty decent cold air with it. Thursday will be a transition day with seasonal temperatures (highs in the lower 50s and lows in the upper 30s), then we drop below normal Friday with highs in the mid 40s and much of the area dropping below freezing (see surface map below showing the large dome of cool high pressure over the southern U.S.).

The surface forecast map for Friday morning shows cool high pressure moving across the southern plains, resulting in weather we are more accustomed to in December. But it will be short-lived as the high moves east and the Mid-South gets back into southerly flow by late in the weekend.
As we head into the weekend though, that high moves to our east and starts funneling warm air into the region again on southerly wind from the Gulf of Mexico. An "average" day on Saturday transitions us to above normal once again as we head into Christmas week. Clouds increase Sunday with rain chances looking decent for Monday as high temperatures rebound back into the 60s, a good 10° above normal. The MWN Forecast below outlines the next 6 days for you.

Christmas week will bear watching closely.  Not only will we be back into a very un-Christmas-like pattern with warm, moist air on strong south wind, but disturbances in the force (obligatory Star Wars reference) will result in rounds of showers and thunderstorms through at least Wednesday (into Christmas Day if you believe some fairly reliable models). In fact, there is some support for potential severe weather and temperatures back near 70° Tuesday and Wednesday of next week. It's too early to define specific or timing, but the signals are definitely strong for a very warm and wet few days leading up to Christmas.

Below are and temperature and precipitation probability forecasts from the NWS Climate Prediction Center for the period December 21-25, indicating a 60% chance of above normal precipitation and a 90% chance (as definite as it gets) of above normal temperatures for a large section of the eastern U.S. The best chance for a White Christmas is unfortunately going to be a plane ride away in the higher elevations of the western U.S. it appears. Not only is grit and grind dead, but so is any lingering hope of a White Christmas in Memphis.

NWS Climate Prediction Center (CPC) temperature outlook for Dec. 21-25 showing a 90% chance of above normal temperatures for the eastern half of the U.S. As close to a sure bet as it comes.

The NWS CPC also indicates a high likelihood of above average precipitation. Combined with the warm temperatures, we'll be watching for the chance of thunderstorms during Christmas week.
Erik Proseus
MWN Meteorologist

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