Hurricane Sandy will continue to push northeastward today and tonight before making a left turn toward the northern Mid Atlantic coast Monday. A developing upper level low through the Mid Atlantic states will capture the storm and hook it back into the coast in a fashion rarely seen. This upper trough and upper low will have no where to go for a few days due to a strong road block in the upper atmosphere through the North Atlantic.
As Sandy encounters the strong upper level low and jet stream it will also make a transition from a tropical system to a non-tropical or extra-tropical storm during Monday. This does not in any way lower the threat for the Northeast and in some ways it may make matters worse.
Sandy is already one of the most expansive tropical cyclones recorded in the western Atlantic and as the transformation to a non-tropical storm occurs the wind field generally will expand even more. This means that gales and damaging wind gusts may occur from the coast of Maine to Cape Hatteras all at the same time. Damaging winds within a purely tropical system are generally confined to within a couple of hundred miles or less from the center but at the current time extend outward nearly 450 miles from Sandy.
Coastal flooding is a strong likelyhood from New England to the central Mid Atlantic coastline Monday and into Tuesday. The wost flooding may come Monday evening during times of high tide. To make matters worse the moon will be full on Tuesday which normal produces tides one to two feet higher at times of high tide. Current storm surge predictions are showing waters to be 3-5 feet above normal mean high tide from southern New England to New Jersey with some spots as much as 6 or 7 feet within funneled inlets. Water rises this high will likely flood many areas along the coast and could threaten the New York City subway system with flooding.
Northeast and east winds are expected to reach 40-60 mph along coastal areas with gusts reaching hurricane strength at times from southern New England to New Jersey Monday afternoon and evening. Interior winds of 25-40 mph with gusts as high as 60 mph can be expected to produce widespread power outages from southern New England through a large portion of the Mid Atlantic Monday and Monday evening. The worst of the wind appears to be in a window from late Monday morning through about midnight Monday night. Winds thereafter should slowly diminish and shift to more of a southeasterly direction. Westerly winds to the south of the storm track through the southern Mid Atlantic states may reach 25-50 mph and could produce low water levels along some coastal areas at times of low tide.
Rainfall is likely to be a problem from near the storm track and on the left side meaning through the central Mid Atlantic states. Rainfall totals of 3-6 inches and locally higher are expected producing widespread river and stream flooding during the next few days. Rain totals to the right of the storm track across New England are likely to be in the 1 to 3 inch range with locally higher totals. These amounts should not produce more than local flooding issues.
Cold air entering the storms' circulation is likely to produce heavy snows through the central Appalachians. Snow totals of 1 to 3 feet are possible through the mountains of West Virginia, western Virginia, and western Maryland. Widespread power outages are expected through these areas due to the snow being of a wet nature and with all of the expected wind Monday into Tuesday.
The post tropical storm Sandy will slowly wind down across the interior Northeast during the mid week period and may take until Friday to fully pull away from the region. Showery rains along with gusty winds should continue Wednesday and maybe Thursday as well before sunshine makes a return from southwest to northeast Friday.