WINTER ARRIVES TOMORROW! WAIT, WHAT?Last Edited:
Grab your Winter coats and cut some fire wood – Winter arrives tomorrow! I love it. Absolutely my favorite time of the year because we get to talk snow and cold and… wait… why does it seem like I lost you somewhere. Oh! I know. You’re scratching your head because you’ve got no idea what I’m talking about. Of course. Let me explain, Winter as most of YOU know it, doesn’t start until December 21st, which is defined by the Winter Solstice. During the Winter Solstice, the sun’s most direct rays are right in line with the Tropic of Capricorn. December 21st is also the shortest day of the year with only 9 hours and 23 minutes of daylight! Alright… so it’s confirmed, Winter is still 3 weeks away… so what exactly am I talking about?
Glad you asked! Seasons can be defined in different ways. There are actually 3 different time frames for Winter that WE observe in the US and several others across the world. The most common is Astronomical which runs from the Winter Solstice to the Vernal Equinox (first day of Spring), the next common is Meteorological Winter which is defined as the COLDEST portion of the year. Average high temperatures are at their lowest point all year. The three month period that corresponds to this definition is December 1st to February 29th. THIS is the season that us in the weather field go by. Wait… there’s another one… Solar Winter, which is the 3 month period from November to February where solar radiation is at its weakest.
Now that that’s cleared up we can begin to look ahead to what we can expect as Old Man Winter prepares to set up shop in our region. I’ve been pretty bullish on the idea that this Winter ISN’T going to be like the last 2. First of all, it’s very hard to get 3 consecutive years to do that, but more importantly, the dynamics are different this year. I explained that the coolest sea surface temperatures are positioned differently opposed to the 2016-17 season. Undoubtedly, that’s going to have a big impact. You simply don’t get the same output with different inputs!
Here's a look at average temperatures for past Novembers... we are MUCH cooler this year than the past 2 and that idea will likely hold true for December.
We’ve been talking about the prospect of a big pattern change on the horizon for the past week. It’s true… it’s going to happen. Although I’ve got a lot of disdain for them, models did a decent job picking up on that idea. Lots of “blocking” over Greenland will allow our jet stream to buckle back and force shots of cold air into the eastern portion of the United States. This means that the North Atlantic Oscillation (NAO) will go into its negative phase. The NAO is one of the upper air patterns that drives our weather here at home. It occurs 18k feet in the atmosphere but has a big impact at the surface. It’s a pattern wellllll to our northeast. It’s Pacific counterpart, the Pacific North America pattern (PNA) also needs to be favorable for us to see cold weather, it will be. It is modeled to go well into its positive phase by next week.
These two upper air oscillations work in tandem to set up a ridge in the west and a trough in the east. The stronger the blocking over Greenland is, the more sustainable this pattern will become. I think cold air sticks around through Christmas this year. That would be a BIG change compared to the past couple years where we saw record warmth through portions of the country. Any real warm weather will be over on the west coast.
This is what the upper air pattern is projected to look like:
Cold air is the first shoe to drop in terms of Wintry weather for us. Once you have that THEN you start looking for storms. You can have all the cold air in the world on top of us but if there are no moisture rich systems, it’s just wasted cold. The farther south the jet dips, the better the chance of picking something up out of the Gulf of Mexico becomes. There are HINTS that something like that could happen at the end of the 2 week period on some of the models but clearly it is WAY too early to speculate. So much hype already! But what I can say is this: Dig the trough and the storms will come.
We’ve got very warm water off shore and that believe it or not can actually HELP the cause for snow here In South Jersey. I’ve had this conversation with several people over the past people days… Water temps don’t concern me one bit – it’s storm track. Put a storm 75-125 miles off shore and BAM, there’s your snow. If we get a coast hugger, the closest inch of snow would be west of Philly. Only time will tell with that one.
As we look ahead into December I think we are colder than average and things pick up in terms of activity. Should be a decent month for winter weather. We need to be vigilant to see if there is any moisture in the pipeline! Cue the “Polar Vortex” hype in 3…2…1… I’ll be in the corner sipping my tea.