December 6, 2013
The Arctic Freeze Train
When we think about arctic air, we usually think about Alaska. Well, this next round of arctic air is actually going to do a reverse trick on our minds. This first week of December, Alaska is actually going to be warmer than many places across the United States. This is all courtesy of a weather pattern that is taking shape. So this week, when we start hearing about temperatures being around 10-20 degrees below zero, it won’t be Alaska, but it will be in the lower 48, roughly from the Pacific Northwest into the Rockies and all the way through the Plains and the Northeast. The only places that will not get hit as bad by this next arctic freeze train will be the Gulf Coast and Southeast, however temps below freezing will still hit this region as well.
So this punch will take place in four phases. The first phase took place earlier this week and that was the winter storm encompassing half of the northern US, with snowfall totals well over 12 inches for some. The second phase will be the first high pressure center that will slide in behind this storm later in the week, while phase three will be another low pressure that will push through the Southern Plains. This will bring interesting weather to the South, including Texas and most of the Gulf Coast. Some places could be seeing their first winter storm of the season. This could become a major problem as well, as the increasing potential for ice is looking to hamper this area, along with some snow. Phase 4 will be the final knock out punch and that is another high pressure center will slide in behind this storm system and bring the frigid air south all the way to citrus country.
That is the impacts that will be felt, by this arctic freeze train, but now let’s look at what makes this type of weather pattern occur.
The image above shows you what was taking place recently. This is the prime setup for the arctic freezes that we are going to be seeing through the month of December for sure, and probably most of January. To the south of Alaska, a very strong Pacific high pressure center settles in. This forces the air to go up and over into Alaska, allowing for Alaska to get the more warm, favorable winds off the Gulf of Alaska. This is one of the reasons that they will be warm during this cold spell that we here in the lower US will see. The second feature is the low pressure that will be forced to come down into the middle of the US. This feature is what is responsible for all the rain, snow, ice, and strong winds that will take place as mentioned above. Behind that is the arctic high pressure center that will push southward. This high pressure slides right down into the US without being slowed down by any weather systems from the west, as everything is traveling from northwest to southeast in this type of pattern.
Now as mentioned earlier, this is taking place right now in 4 phases. The first phase was the first low moving through December 3. The second phase will be the first arctic high that will settle in and bring air temps to around -20F along with wind chill values in the -40F range. The third phase will be the development of another low that will push out of the Southwest Rockies and towards the east. This will then usher in another round of rain, ice, sleet and snow, along with gusty winds. Behind this low will be phase 4 — the next arctic high — due to the low pressure being further south. This will allow for the high pressure to slide further south than the one in Phase 2, and this is where the cold air will then enter into the Deep South.
This setup that we are seeing to start the December 2013 period out can be correlated to a blocking pattern. The reason we call this a blocking pattern is that in a typical northern hemisphere setup, the air should flow west to east. However, in this blocking pattern, our air is moving in a more southwest to northeast and then northwest to southwest flow. This creates stronger storm systems, like what we will be seeing, along with longer periods of this type of weather because the weather is forced to slow down and take longer to move along its path than if it was a west to east flowing air pattern.
That is the arctic freeze train and how it impacts the United States. So bundle up and enjoy. The train has arrived and will be here for most of December.
Featured Image Credit: Thinkstock