Another “tool” of the trade that I examine when I analyze weather patterns is the Teleconnection charts. These teleconnection indices have MAJOR implications on our weather here in the NE and Mid-Atlantic area. During the winter, they have a heightened importance because they indicate how much cold weather will be able to sustain itself in the area enough for weather systems to produce precipitation (snow, rain, etc..). So we begin.
Now, we start with the chart I have up. This is the most recent teleconnection chart. It starts with the PNA(Pacific North American Pattern). This gives us an indication of the ridging in the Pacific. This is important to stay positive. This tells us that a ridge will build in the Pacific to allow weather systems in the Pacific to go up and over Alaska then down like a roller coaster to the North American continent. We call this “downstream“. As you can see it is to remain pretty positive through almost the middle of this month. That’s a “good” sign if you want storminess. A negative PNA indicates flat, or no ridging and west to east systems have no momentum to build up anything and just fly by.
Next, we go to the EPO (Eastern Pacific Oscillation). This indicates how the blocking pattern is on the Pacific side. A negative EPO creates a block that allows cold air to seep into the eastern part of the country on the Atlantic side. Thus, if you like snowy weather, this is a real critical element. This is shown to stay slightly negative until the middle of the month when it looks like it’s trending positive. We will have to see. A positive EPO you can kiss cold weather in the east goodbye because that means the cold air pours down into the Rockies in the West and creates a trough there and a ridge in the East. Thus, goodbye any hope of a good snowstorm mostly anywhere.
Finally, and perhaps the MOST important is the NAO(North Atlantic Oscillation). This index gives us an indication of blocking above Greenland. This LOCKS in the cold air if there is blocking and it slows down storms coming into the East. You don’t need an absurd negative NAO to get a good snowstorm. You don’t even need an all negative NAO. We just need something resembling blocking to keep cold air in long enough for a system to get to the Eastern seaboard. Ten of our snowiest winters dating back to Snowmageddon in 2010 the NAO has been very negative. Now, if you were to look at this indicator through the middle of this month this is not a good sign. This means you have cold air, but it just can’t stay long enough. And with it going very positive in the middle of the month this could mean there isn’t enough cold air around for a big East Coast snowstorm.
Now, can we still get a snowstorm over the next few weeks-YES? The chances are slim, because you may have some ridging. We may have a ridge in the west. However, with no blocking in place any precipitation will be a mix, snow-rain, rain to snow, snow to sleet, etc.. In other words messy!
Winter isn’t over folks. It’s just dampened. Patience!
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