(Current US Surface Weather Map Indicates a Cold Front Advancing East Across The Region)
Unseasonably warm conditions will briefly come to an end tonight and tomorrow as a cold front advances towards the east ushering cooler and more seasonal temperatures for the Northeast. Expect showers of rain out ahead of the front across the region before temperatures fall back to what we would expect for early December. Temperatures will warm back up by Friday , though not as mild this warm up should last through the weekend and staying here through the better part of next week. Along with the mild conditions, we can expect inclement weather to affect the parts of the region, mainly away front the Atlantic coast as a stationary front sets up along the lower Great lakes increasing the chance of rain on Friday and Saturday across western New York State. Looking ahead, the long range weather forecast still supports the idea of an increased cold and snowy weather pattern setting up over the Northeast. One of the parameters which supports this forecast is the North Atlantic Oscillation index (NAO). We are currently observing a positive phase of this oscillation, which allows storm systems to move out quickly and doesn't allow the cooler temperatures to stick around much. However, with time, it looks as if we will be entering a negative phase of the NAO later in December.
Graph from National Weather Service Climate Prediction Center
(Click to Expand Image)
Typically, when the NAO goes into a negative phase, high pressure sets up over the oceans in the northern latitudes. Essentially, this acts as an atmospheric block, allowing frequent shots of cold arctic air to flow south into the central and eastern US, and locks it in place lasting as long as the NAO stays in a negative phase. This also allows for big storms to form and move up the eastern seaboard. The current forecast calls for a more negative NAO to set up by mid December, in the mean time we can expect temperatures over the Northeast to continue to oscillate between average and above average with no big storms on the horizon for the eastern seaboard.
The Graphic Below Explains The NEGATIVE PHASE of The North Atlantic Oscillation
Graphic from National Geographic Magazine, March 2000
(Click to Expand Image)
The Graphic Below Explains The POSITIVE PHASE of The North Atlantic Oscillation
Graphic from National Geographic Magazine, March 2000
(Click to Expand Image)
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