•Multiple moisture starved clippers will impact the region over the next few days
•Threats of snow and rain showers Thursday through Sunday, minimal accumulations are expected across the region, a general coating to one inch or two is possible (a few models show more snowfall which we will continue to monitor)
•Temps start to drop over the weekend and return to below normal for next week and beyond; Subzero low temps will likely return to the region
• Changes will bring a colder and snowier pattern that may linger into February
•Snow threat increases across the region for as early as the middle of next week
The remainder of the week we will deal with a few moisture starved clippers that will bring a continuos threat of snow or rain showers. No more than a coating to one inch is expected with these systems. With each passing clipper we will also begin a gradual step down in temperatures as we head into the weekend, and by next week things will look and feel drastically different. As we mentioned in the earlier blogs, it appears the weather pattern will evolve into one that will spell the return of arctic temperature and potential snow storms. We spoke about the North Atlantic Oscillation (NAO) being in a negative phase, and the impacts that can have on the storm track. Next week will be a good indicator of what can happen when the NAO is negative.
It appears that as we get past the nuisence snow and rain showers that will impact the region from tonight straight through Sunday, the bottom will start to fall out on temperatures. This will set the stage for a return of winter across the region for the remainder of the month and possibly into February. Generally, when cold temps and a negative NAO is driven through on the East Coast, it is a primer for Nor Easters, and makes snow lovers jump for joy. Currently, at least one model is trying to get the party started as early as the middle of next week.
Lets start with and overall look at the pattern that is beginning to evolve:
A jet stream is a current of swift moving air that drives our weather from west to east across the country. High and low pressure systems have a definitive impact on the flow of the jet stream, and thus an impact on the track that storms will take. Remember to always think of the atmosphere as fluid. Consider the jet stream as a creek. Think of the storm as a leaf that fell from a tree. When the leaf falls into the water, it will be carried in the direction that the water flows. When a creek is filled with rocks (tall rocks, short rocks, fat rocks, thin rocks), the water and leaf will flow around the rocks the best way it can. The rocks are your pressure systems. The water is either forced up and over (high pressure), or under and around (low pressure).
These “rocks” in the jet stream form what we know as ridges and troughs. They force the jet stream to shift around warm air and cold air, as we have marked with blue and red arrows on the map. See that area of high pressure on the top right of the map? That is what we call a “negative NAO.” A negative NAO is basically an area of high pressure that forms in the North atlantic. The reason why we pay so much attention to the NAO is because of its effect on the weather in the Northeast. This high pressure causes a trough in the eastern half of the country, this not only allows cold air to enter the picture, but it slows down the storm track and forces storms up the East coast, as opposed to out to sea. This set-up is the foundation for a significant nor easterly impact on the Northeast.
Below is an image we have used a lot over the last few days that shows areas of high and low pressure, as well as their corresponding ridges and troughs in the jet stream. I have marked the general location of the jet stream with arrows.
Have you been enjoying the forties and fifties? Well, this pattern change will provide a stark reminder that winter is far from over. Below is the Euro’s low temps for next week across the region.
Yes, the subzero low temps will try to make a return. It also appears that this next wave of cold air may have more staying power than the previous cold snap. All we need is a storm to form along the coast and we would have brought this pattern change full circle. With that being said, I present the European Model, which is the first and, so far, the only model that is already trying to sniff out a Nor Easter for the middle of next week. Reminder, this is only one model and it is almost a week out. It will likely waffle many times, and even lose this storm completely. But it’s more important to point out that the pattern is going to create fertile environment for us to have a potentially stormy end to the month and start to February.