Hi, Good Morning!
It’s been a week for me personally as I’m dealing with the loss of my father, but weather and writing (even with grammar that some of you hate) has always been a great outlet for me, so this morning I decided to take a stab at talking through how it’s been so cold, but not as snowy as some have been hoping for. Yall only need to read all this if it’s your thing to nerd out or learn about weather.
Let me start by showing you Dec and Jan (incomplete) vs average temps so far- just to highlight that we are running a below normal temp winter now for nearly two months!
Above is December vs Average, below is January, which is going to continue to drop given the current air mass.
Yeah! It’s been pretty cold, especially when compared to the last few winters we have seen. It’s this pattern that helped pave the way for this week’s snowfall across the south and boy was it a doozy.
Just a few images the summarize just how historic the southern snowstorm was.
The first image is snow depth on the ground across the Deep South, the purple and pink areas represent 6”-10” amounts, which were recorded in Louisiana, Florida, Georgia and South Carolina where numerous records were broken, in some cases the 100+ year records were quadrupled.
The second image is current snow depth for the entire country, followed by the northeast and northern plains.
These images help drive home that when the snow ended across these southern states, Louisiana, Georgia, Florida and South Carolina had more snow on the ground than….
Parts of Michigan, Minnesota, New York (Hudson Valley Included), most of New England, parts of Montana, South and North Dakota.
In fact, Milton Florida received more snow in a single day than Boston has received in a single day, in four of its last six winters. The airmass responsible for this event also brought single digits temps all the way to nearly the gulf coast, also shattering many low temp records across multiple states. This was truly an historic event, once in a lifetime for those who experienced and were able to watch it unfold. Here’s a crazy image I found to drive this home!
Yes. This is showing what you think it is, Milton Florida saw more snow in a single day this winter than all of those cities in Canada have seen thus far this winter!
HOW!? Easy….
It’s important to understand how these type of event impact our weather here at home. While this winter has actually been quite cold, with December finishing below average, and January trending to potentially be a a top 10 coldest, it hasn’t been as giving in the snow department. We have seen a lot of nickel and dime events, without any large winter storms, the below average cold across the region, and this historic event across the south highlight a pattern that is actually now all that conducive for moisture laden winter storms. You may have heard us use the word suppression before, air masses such as these, with persistent disruption of the polar vortex, can actually suppress the storm track far to our south. We saw this a few weeks ago with snow across the southeast, and again with a major winter storm around DC, and again this week across the Deep South.
Remember, cold air is also typically dry air, and while cold air is a key ingredient to a major winter storm, it also requires an infusing of moisture. The moisture is typically provided by the sub tropical jet stream to our south. If the sub tropical jet stream is suppressed southward, so it the moisture, and the best winter storms occur where these air masses clash. We need blocking in the North Atlantic to help buckle the jet stream north, without it the storms passes west to east across the country as we are cold. This pattern means lake effect snow, low temps, windy and occasionally we get clipped by a storm developing along one of these boundaries where warm meets cold.
If we are going to see a widespread heavy snowfall it will be with strong -NAO (high pressure across the North Atlantic) or on the front side of reinforcing cold air or while a cold air mass is on the retreat, always watch the relaxing/reenforcing periods for storm potential. When you hear the term “it’s too cold to snow” realize that is not entirely true, it can be too dry to snow, cold air holds less water vapor, it needs a source of moisture, so far area down wind of the Great Lakes have found their source in the unfrozen lake waters, beyond that the tundras of Canada to our NW have very little to provide.
Anyways, if you stuck with me through all that, I appreciate ya.. thanks for coming to my Ted Talk! Milder air builds in starting today! By that I mean 20’s! Enjoy…
-Alex