The active winter of 2008-2009 marches forward as the next in a series of winter storms sets its sights on the Twin Tiers for later tonight and into the day tomorrow. This next storm will bring a widespread significant snowfall to the entire viewing area with the possibility of some mixed precipitation affecting areas to the south and east of Binghamton....particularly across northeastern Pennsylvania and the southern Catskills. As always, the eventual outcome of the storm will depend greatly on the track of the surface low pressure system....but confidence is increasing that this will be a particularly high impact event across much of the area.
Snow is expected to rapidly develop from southwest to northeast between about 11PM and 3AM tonight. The combination of an increasingly large horizontal temperature difference at an altitude several thousand feet above the earth's surface....a process meteorologists refer to as "frontogenesis"...and another factor known as equivalent potential vorticity, or "EPV"....will result in the formation of a northwest to southeast oriented band of heavy snow that will translate across the area at some time between 4AM and 10AM. Snow may briefly accumulate at the rate of 1" per hour at some point during this six-hour period....resulting in rapidly deteriorating road conditions and a very tricky Wednesday morning commute. Most areas will receive at least 3-6" of accumulation by the time the snow lightens up....with some localized areas perhaps receiving as much as 7". The snow will become much lighter by around noon.
Light snow will continue periodically through much of tomorrow afternoon, but as warmer air begins creeping into the upper levels of the atmosphere the snow may eventually change to a mix of sleet and freezing rain in parts of the area....especially across northeastern Pennsylvania and the southern Catskill Mountains. Locations from Binghamton north and west should remain all snow, with perhaps a brief period of snow/sleet mix in the greater Binghamton area.
There is a slight chance that parts of the area could recieve another period of heavy snow late tomorrow afternoon into tomorrow evening as a developing coastal storm rapidly intensifies in the vicinity of Long Island....but that remains a "wild card" at the moment. Be sure to check the main weather page on our website for updated forecasts (including snowfall graphics) later today and tomorrow.