Looks like our streak of mild days is coming to an end as winter will finally make an appearance in Minnesota and likely stick around for the foreseeable future. Not all that shocking considering its December. But what a run we have had with 2 weeks of gloriously nice weather for this time of year. But now the weather pattern over North America is changing. That river of air at the top of the atmosphere, called the jet stream, is diving southward into the southern U.S. This allows cold arctic air to get dislodged and move southward into the eastern half of the country. This is the exact opposite of the pattern we have been enjoying for so long. But because the polar jet stream gets kinked around the globe, our colder than average pattern may hang around a while… quite possibly through the end of the month! You can see for yourself in the images above that once the jet stream pushes south, it stays in roughly the same spot and orientation all the way through at least Saturday.
What may be even more remarkable about our current weather scenario though is just how much the atmosphere will change over the course of one day. The storm that’s bringing reality back to the state will suck Gulf of Mexico moisture northward. And not just a little, but enough to allow dewpoints in the metro to surge into the 50s… something that is so rare during the month of December that I can’t actually remember it ever happening. But it doesn’t last long as the cold front moves through and cold and very dry air surges quickly southward dropping dewpoints to more seasonable normal levels.
While some snow is expected, mostly northwest of the metro, total accumulations are likely to be mostly light. But the combination of falling snow and wind could lead to some serious travel issues Monday and Monday night in greater Minnesota. Check out the graph in the images above. The graph shows the plotted forecast hourly wind speeds and wind gusts from the computer models. This would indicate that there is some potential for 60+ mph wind gusts in the metro Monday night. With winds like that, it takes very little snow to create white out conditions. The metro’s chances of getting enough snow to cause white out conditions are pretty slim, but reduced visibility at the very least can be expected Monday evening, along with icy roadways as any and all liquid on the ground will quickly freeze as colder air arrives.