In today's Winter Weather Work Shop with Storm Surge LLC., I shared by thoughts and concerns about the potential for not one but two significant accumulating snow events. While we mostly focused on the latest model guidance coming out this morning, this evening I want to touch on real observations that are peaking my interest.
First, look at the upper low around the Aleutian Islands. This is an extremely important teleconnection as this storm is pumping up the ridge over eastern Alaska and western Canada. In short, this storm is setting up the upper level wind pattern to drive arctic air into the central and eastern United States. Even more interesting though are the number of dynamic disturbances showing up on the water vapor satellite picture from the Polar and Arctic jet streams. These disturbances are rapidly diving south with the first moving through the Great Lakes tonight and exiting through New England and the Northern Mid Atlantic tomorrow evening. This is the first of several clippers that will move through the eastern United States and it is these clippers that can bring a lot of interesting winter storm potential to the region.
The next area that has my interest is all the moisture pooling off of the western coast of Mexico. In the discussion today I noted that the models were not handling the convection developing over the tropical Pacific very well and thus were producing a variety of surface low pressure system but no corresponding 500 MB representation. That seemed very fishy to me, but when you see the water vapor satellite you can clearly see a steady increase in convection developing and enhancing the Sub Tropical jet stream. This observation is more important for the potential storm at the end of this week.
Back to Monday night! A strong clipper is going to be diving south from the central Plains towards the Ohio River Valley and then off the Delaware Coast. This low will rapidly turn northeast through the coastal waters of New Jersey and towards the New England coastal waters Monday night into Tuesday morning. Here in lies the potential for a rapid significant bombing out of the clipper that some models show and some don't. The thermal gradient from the sea surface temperatures, which are running above normal, to the arctic air will easily exceed twenty degrees Fahrenheit. This is basically like throwing nitroglycerin on a small fire. Now, if this does happen, look for a focus of very heavy snow from the immediate New Jersey coast (potentially just northern Ocean and Monmouth counties of New Jersey), New York City and Long Island, Connecticut, and eastern New England. The gradient from heavy snowfall to nothing at all will be VERY tight with this type of set up. How much is a complete unknown at this time, but I do know this storm will be moving fast so I can't see more than 6 inches if the storm will linger for 4 to 6 hours at most unless the snow ratio falls to 20:1.
The next storm is more of a phasing potential with another clipper and a Sub Tropical disturbance. I am warning everyone that the models barely have the influences of the Sub Tropical disturbance handled. The GFS is attempting to incorporate more influence from the Sub Tropical jet stream but in typical epic fail form from the GFS, tries to phase every disturbance in North America in doing so. Considering the way the rest of the pattern is setting up, I can't see how a low pressure system tracks into the Great Lakes in this set up.
The potential is certainly there for a significant accumulating snowfall region wide for Friday and in this case there will be no concern with cold air issues. What is uncertain is just how will the disturbances interact and the exact storm track potentially too far east or south. Time will tell, but I can tell you that tonight I am very confident that we are in for a very fun end of January and an even more fun month of February.