High pressure currently over the northern plains will move across the Ohio Valley tomorrow, reaching the east coast by Tuesday evening. This will keep sunny skies and seasonably cool temperatures locked in over the region for the next 72 hours.
Two unphased shortwaves will move off the coast Monday night. The northern one may cause some clouds to overspread mainly eastern New England. The southern wave will move out over the Atlantic and intensify into a large ocean storm on Tuesday.
High pressure slides off the coast Tuesday night, giving way to strengthening low pressure developing in the central plains (Kansas / Nebraska). This storm will strengthen and turn northeast over the Ohio Valley. Light precipitation will move into the region Wednesday afternoon with the leading edge of warm air advection. All precipitation should begin in the form of snow.
Low pressure moves into New York state Wednesday night. It is still uncertain whether a secondary low will form on the coast. This will dictate the precipitation type late Wednesday night into Thursday. If energy is transferred to the coast, we would remain all snow and could receive significant accumulations. Otherwise, snow will mix with rain Thursday morning. I am leaning toward the latter senario, with total snow accumulations around 3" to 5". See the latest forecasts and analysis in the winter weather outlook.
Colder air moves south into the region as low pressure moves northeast, and skies will clear for Friday.
Another shortwave rotates south out of Canada and through the Ohio Valley Friday night into Saturday, with low pressure in the upper Mid Atlantic region by Saturday evening. This should spread light snow across the region through Saturday and Saturday night. GFS and Euro have expressed the potential for coastal development and snow continuing through Sunday. This will have to be monitored for another plowable snowfall. Any blocking, and this could be a large storm.
High pressure regains control on Monday (23) before the next storm threatens the middle of next week.
Through the next two weeks, -PNA ridging will regain strength over the central Pacific, forcing progressive troughs impacting the western US. Angular momentum and convective tendencies over the equatorial Pacific support a solidly La Nina atmosphere. GWO is currently deep in phase 1, and the latest MJO wave is collapsing in the western Pacific. There is no indication of this pattern changing.
GFS ensembles are maintain a neutral NAO with a mid Atlantic ridge look similar to last November. This will allow progressive troughs to traverse the CONUS. With the -PNA feature in control, the Mid Atlantic up to NYC will have to deal with rain from most storms, while New England's best potential for snow will come with Miller B coastal development.
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