Meteorological winter begins - WMC Action News 5 - Memphis, Tennessee

Meteorological winter begins

(WMC) -

Although the winter solstice doesn't take place until Dec. 21, meteorological winter began Dec. 1. 

For climatological purposes, meteorologist consider the full months of December, January, and February as winter which is typically the coldest three months of the year.  This also make for easier record keeping for the winter season. 

Whereas the winter solstice is based on the sun's alignment with Earth. 

So, with meteorological winter in progress, let's take a look at the forecast for the winter season. 

The latest forecast from the Climate Prediction Center is calling for above average temperatures for the season.

This is prediction is due in large part to the weak La Nina that is taking place in the equatorial waters of the Pacific. 

This is a below average cooling of waters in that part of the world which in turn means that less moisture is released into the atmosphere allowing for a drier than average pattern to set up in the southern U.S. 

This drier pattern allows for less moisture and cloud cover allowing more incoming sunshine which in turn heats the soil making for warmer temperatures over that particular part of the country. 

The long-term forecast is based on the strength and longevity of the current La Nina. 

Should the La Nina weaken or diminish all together then that would impact the eventual outcome. 

But, current indications are that the pattern will remain through the next 90 days allowing for this warmer pattern. 

That is not to say that there will not be any significant cold for the season because we also have to take into consideration the pattern of the polar jet stream. 

The jet can take a dip south and quickly bring a quick shot of cold air to the region. 

This is expected to occur within the next few days of this writing and is likely to occur several more times during the season. 

These quick bursts of cold air are expected to be followed by periods of above average warming and and when averaged for the entire season would allow for overall temperatures to be above average limits. 

The pattern also suggest an average to slightly below average amount of precipitation for the season.

But we must keep in mind that a quick shot of cold Canadian or Arctic air diving south just in time to converge with a southerly flow of moisture could create the right mix for snow or ice during the season. 

In a pattern like this, the Mid-South could be in line for a round or two of wintery precipitation. 

Overall, long range forecast are difficult but can give some indication of what could be.  

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