#tristatewx #INwx #ILwx #KYwx Major changes coming to the Tri-State starting this week. The general pattern will change, unfortunately unless you like the cold. This is one that will stick around a while. The cool down will come in waves. Through Tuesday things will slowly warm ahead of a cold front. It will bring rain chances, but nothing too different that we havent had to deal with with over the last couple weeks. As front moves east Wednesday, temperatures will start the tumble, it wont be until Thursday however before the meat of the cold air arrives. In fact, On Thursday. Most of the Tri-State wont even make it to 40°F for the High Temperature! Coldest High for the day (Nov 14) is 25°F set back in 1986. That looks thankfully safe, but its till going to be quite cold and below the average for this time of year. The New Pattern: What makes this cool down, different from the previous ones. It is very true, over the course of the last year really weve had these cold spells where the High/Low Temperature is 10 -15 degrees below the average. Weve had that for quite some time. Now, what is DIFFERENT is what will develop in the the High Latitudes. Last Winter we had frequent cold spells. However, most of the time they were in and out in a few days. This was because the North Atlantic Oscillation (NAO), was in a positive or neutral phase or zonal. So, what changed? An overwhelming majority of data indicates it will go negative over the next week or so... and stay that way. When NAO is negative, that means the High Latitude winds that would normally blow west to east are being slowed down by a block. This occurs when a Ridge develops over the North Atlantic, near Greenland. When this happens it causes a traffic jam in the mean polar jet stream and once the cold air drops in, it cannot move out, or does so very slowly. This means once the temperatures drop this time, they will not recover nearly as quickly. In addition, this keeps a cold dense layer of cold air near the surface. No big deal right? What happens when a storm comes from the southwest (as they have frequently)? We now have a recipe for Wintry Mischief. In fact, I am already tracking the potential for wintry precipitation as soon as Sunday! Either way, it appears Winter is arriving this week and its planning on settling down for a while.
Posted on: Sun, 09 Nov 2014 23:57:41 +0000
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