..Record cold temperatures on Thanksgiving/Black Friday for much of the Northeast/New England.The majority of area will stay well below freezing, while low temperatures may reach the single digits on either side of zero. The much below average temperatures in the Northeast will slowly ease back toward typical late November values by the weekend (and likely above average minimum temperatures).
Significant snowfall beginning late Thursday and ending Friday morning. A developing low pressure system will track northward along the Eastern Seaboard Thursday and Friday. Snow associated with this low will affect Eastern Ontario beginning Thursday evening. Snow will continue Thursday night and end Friday morning.Current indications are that total snowfall amounts will be in the 10 to 15 cm range. Snow may affect the drive home Thursday evening,.
The highest snow accumulations are expected underneath the upper level low itself across southeast Missouri and southern Illinois where 4 to 8 inches is forecast. Farther east across the Ohio Valley, the central Appalachians, and the interior Mid-Atlantic (west of I-95), generally 1 to 2+ inches is expected. Freezing rain will also be a concern across some of these same locations with generally up to a tenth of an inch expected across the lower Ohio Valley.
As the first significant interior Northeast wintry storm departs and leaves behind a trof accompanied by very cold temperatures under the control of build high pressure, we look towards the SW Atlantic Ocean, in the area between the northern Bahamas, eastern Florida coast and the Georgia coast, where clouds gather and conspire to initiate cyclogenesis for the next storm that could affect the easternmost areas of the Mid-Atlantic and Southern New England
Lake effect snow is common across the Great Lakes region during the late fall and winter. Lake Effect snow occurs when cold air, often originating from Canada, moves across the open waters of the Great Lakes. As the cold air passes over the unfrozen and relatively warm waters of the Great Lakes, warmth and moisture are transferred into the lowest portion of the atmosphere. The air rises, clouds form and grow into narrow band that produces 2 to 3 inches of snow per hour or more.
Developing low pressure will move along the Eastern Seaboard today, leading to widespread precipitation. Rain is expected across the Southeast, Mid-Atlantic, and coastal Northeast today, while the interior Northeast will be cold enough to get snow. Rainfall totals will be around an inch in coastal New England, snowfall totals could be high in northern New England, with 6 to 8 inches.
There is a growing signal supporting ample leading wave/frontal genesis and deep moisture return to would fuel heavy rain/convection expansion northward across the east-central then eastern U.S. Moisture feeding back into a sharpening baroclinic zone meanwhile presents an organized snow threat through the Appalachians/Ohio Valley, with ample lake effect enhancement lee of the Great Lakes. Significant early season snows are possible.
Very cold weather is expected to be in place across the Great Plains through at least the end of the week with high temperature departures from normal ranging between 10 to 25 degrees below average from the Canadian border to the Rio Grande. Upper level disturbance will approach the Central Plains tonight, increasing snowfall coverage with locally moderate intensities into the central High Plains. 2-4 inches, locally higher, can be expected by Thursday afternoon.
Monday night/Tuesday is the focus for the next system. This one a deepening low tracking from the southern Plains to the Great Lakes will bring another round of rain showers to everyone, potentially some embedded thunder, and plenty of post-frontal wind. The biggest change/trend has been for the axis of heavier rainfall to shift southward. This has lowered QPF amounts to around a half inch to three quarters of an inch.