Big storm poised to slam much of East Coast, but much of Vermont is just not positioned well for the best snow

Our late-week east coast storm is now taking shape and deserves a disproportionate amount of analysis this update. It's a big storm and a challenging one to forecast and will continue to be even within hours of the event. By Thursday morning the storm will be centered over Illinois and Indiana and move due eastward into Ohio and Pennsylvania before transitioning the bulk of its energy to either the New Jersey coastline or the Delmarva. The question of where this transition occurs is one of a few critical questions plaguing prognosticators as we get closer to event time. Fortunately, I only have to answer for Vermont but the storm will have a broad impact and will likely produce coastal flooding, heavy rain flooding, high winds and heavy snow in multiple states.

I continue to hold out hope that we see a shift in some of the data. This still could occur even at the eleventh hour and the high country of Vermont would perform exceptionally well. Given the current expectations and the data available to us, we are not in the greatest position to see heavy snowfall from this storm. The biggest issue with the storm is the following. With most storms, the best areas of precipitation are found to the north and to the west of the area of lowest central pressure. This varies depending on the character of the storm and specifically on the maturation of the storm. This particular storm is expected to undergo a very early maturation across the Midwest, peak somewhat across Ohio and then have a 2nd peak somewhere off the east coast after it makes its coastal transition. The early maturation is going to allow a strong upper air low pressure center to form and across Pennsylvania and close off. A closed upper low shifts the areas of best precipitation from the aforementioned north and west of the area of lowest central pressure to the west and south of the area of lowest central pressure. Essentially it takes all the moisture and rotates it counterclockwise 90-degrees, sometimes more, sometimes less depending on the strength of the upper air low and the occlusion. Vermont will be positioned decidedly north of the big low pressure center, not a bad position traditionally speaking but bad for a storm like this. We won't be where the coldest air is and we will have a tough time getting into some of the deep moisture which is likely to be confined to the south and west of us.

Our first day of March will be cooler than the last few in February but readings are expected to remain above freezing for the most part as both rain and snow advance into New York State. The snow is expected to become heavy over parts of central and most of western New York Thursday night and some of the moderate snow is expected to make some inroads into Vermont Friday morning but mainly across the high country with marginal temperatures supporting only mixed precipitation or rain in the low lying areas. The heavier precipitation might even reach the Mad River Valley for a time producing the same elevation sensitive snowfall. Given the current data however, the best snow will fall across the Finger Lakes region of New York, the Catskills of New York and the Pocono Plateau of Pennsylvania along with other elevated areas of northern Pennsylvania. If we get northward shift in subsequent data I would raise my expectations for Vermont but right now I think its 1-6 inches across the north and 4-10" across the south. It will range from not much of anything for locations like Jay Peak to perhaps as much as 10 across for the summits of places like Stratton and Mt Snow. The Catskills of New York will also see elevation sensitive snowfall but are in a much better position to get the deep moisture and are could see 2-3 feet of snow. Given the strength of the storm, we could see some very gusty north winds Friday even if its not snowing hard. 

Most of the precipitation will be over by Friday night in Vermont and across most of the east coast by early Saturday though the mountains could see flurries continue throughout the day along with temperatures in the 30's. Sunday will feature more of the same on temperatures but perhaps a little more sunshine. Early part of next week appears dry and at least partly sunny with seasonable March temperatures and calmer winds verses the weekend.

A very substantial amplification in the jet stream still appears likely by the middle of next week and thus another east coast storm is a likely result. Once again, this situation looks just a touch more promising but will require some big secondary east coast action to occur. The initial storm, as mentioned in the last post will likely occlude deep in the Midwest and won't be good for much of anything. This is a terrific pattern for all kinds of east coast action but we obviously just need the right kind of storm. Next week marks another good chance, but likely not the last as the "cool and stormy" mid latitude pattern is set to continue at least until the middle of March.