Winter is Here!

Today is the first official day of winter (at least for locations west of the Eastern Time Zone) and it certainly feels like it here in Oklahoma! Here are a couple fun facts about today.

1. The winter solstice is officially at 11:30 PM CST. This is the moment when the sun's rays are directly over the Tropic of Capricorn (~23.5° South in latitude). It's at this point in the year when the sun's rays are most indirect in the Northern Hemisphere. This means solar radiation is not as high and getting a tan is a bit more difficult!

2. Today is the shortest day of the year with 9 hours and 42 minutes of daylight in Tulsa, and tonight will be the longest night. That gives us a night that lasts a whopping 14 hours and 18 minutes.

3. Since we experience colder weather in the winter, it would be easy to assume the sun is further away at this time of year given our elliptical orbit. But, that is not so! In early January, we actually make our closest approach to the sun with just 147.1 million km between us and that fiery orb!

4. Even though we receive the least amount of daylight today, this is not the coldest time of the season. There is usually about a month lag between the minimum (or maximum) solar radiation we take in and the coldest (hottest) time of the year. Water temperatures have a lag time that is nearly twice as long.

Fortunately for us, most of our 9 hours and 42 minutes of daylight will be spent in sunshine today. We can say good-bye to the first major winter storm to strike our part of the country before another glancing blow of winter comes our way. The previous storm brought snow as far east into our immediate area as Ponca City, but accumulations were relegated to far northwestern Oklahoma. Parts of the panhandle received over a foot of snow with drifts that towered several feet high! Needless to say, they will enjoy a White Christmas this year. The map above shows the current snow cover in the U.S. A number of places used to a White Christmas may be left with barren ground this year as it appears with a continued warmer pattern for the Eastern United States.

A White Christmas may not be in the cards for us this year, but that doesn't mean we will go snow-free through Christmas. Another storm system is diving into the High Plains, bringing another blast of colder air. The system will be lacking moisture once it reaches Oklahoma Thursday night, but enough upper-level energy may be in place to spawn a period of flurries or light snow by Friday morning. The models are inconsistent on the timing and placement of the moisture so I'm not gung-ho on our chances just yet. If the flakes do fly, travel impacts would be rather minimal. Temperatures are expected to rise well above the freezing mark on Friday with near-surface ground temperatures in the 40s. Still, it is a big travel day and we will be closely monitoring this system.

As we look ahead to the holiday weekend, our weather will likely be quiet and seasonable despite a very active jet stream. In fact, by Christmas Day, temperatures will likely climb to the 50° mark with sunny skies. That's not a bad gift from Mother Nature!

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