Today is the first day of spring, an occasion when the sun's rays shine almost evenly between the northern and southern hemispheres (just before 1:00 PM Eastern, if you were wondering) before shining more directly on the Northern Hemisphere for the next six months. Did you think that would mean warmer weather? You poor soul.

Slate's in-house weather geek Eric Holthaus wrote an excellent piece yesterday afternoon explaining why the United States will see more cold (and possibly snowy) weather for at least the next few weeks thanks to an event called a "rex block."

The forecast shows a "Rex Block"—named after the first meteorologist to crack this particular pattern—currently forming off the West Coast. Blocking patterns are pretty much what they sound like: quasi-stable arrangement of high and low pressure centers that join forces to gum up the works of the atmosphere, freezing in place—and in some cases, amplifying—the weather du jour. In this case, winter.

This kind of set-up is conducive for cold air to lock into place where it's been for what seems like forever, allowing the chance for more snow as potent weather systems interact with the stagnant airmass.

The Climate Prediction Center notes the high likelihood that temperatures across much of the eastern United States will fall below average for this time of year, while the western United States continues to see warm and dry conditions.

Here's the CPC's 6-10 temperature outlook:

...and the agency's 8-14 day temperature outlook:

It's important to note that while the eastern United States seems excessively cold this year, the perception of an exceptionally cold winter is only true for parts of the Upper Midwest. Most of the northern hemisphere has been incredibly warm for the past few months. Verkhoyansk, Russia is notable for its title as one of the coldest locations in the northern hemisphere and for seeing some of the largest temperature swings on earth — its record high is 99°F and its record low is almost -94°F.

This winter, however, the Russian city has seen remarkably warm temperatures. Verkhoyansk's average high for March hovers around zero degrees Fahrenheit, yet Wunderground shows that the city will see temperatures in the low- to mid-20s (above zero) this week.

However, for our friends on the east coast, the recent cold and snow wasn't enough. Nature is about to rub rock salt into your wounds, as weather models are hinting at the possibility of another winter storm across parts of the east next week.

At this point it's wise not post the model generated images themselves since there's too much uncertainty, and uncertainty plus authoritative-looking model imagery equals social media rumors galore. Some of the models (like last night's GFS run) want to send the storm out to sea with a smaller impact, while other models (like yesterday morning's ECMWF) want to drag the storm up the coast and cause problems from North Carolina to Maine.

It's prudent to keep in mind that just because today is the first "official" day of spring, March and April can breed some pretty big snowstorms. While the north stays cool, the south is beginning to warm up and more moisture from the Gulf of Mexico is available for storms to tap into. This influx of moisture into still-cold air can lead to some heavy duty snow. For example, a major blizzard dumped over 2 feet of snow in Boston on April Fools' Day in 1997.

A joyous vernal equinox to you and yours, and stay warm.

[Images via AP / CPC / CPC]