Sunday and Monday Storm Snowfall Prelim

This is our first crack at the snowfall potential for the upcoming Sunday and Monday storm. We are growing more confident that the primary storm coming up through the Ohio Valley will remain intact all the way up into western New York by Sunday night, while the secondary, coastal storm running up the eastern seaboard will remain weak. Once the storms meet up in upstate New York they will merge into one, stronger storm, which will track northward through Quebec on Monday. What does all of this mean? It means that this will just be a rain storm from the coastal Maritimes to the Middle Atlantic coast of the U.S.. Milder air in the mid levels of the atmosphere will change any snow over to sleet then rain across much of the interior northeast, including central New Brunswick and perhaps into parts of extreme southern Quebec. East to southeast winds could warm the low-level temperatures over western New York and into the Hamilton and Kingston areas of Ontario later Sunday, causing the snow to change to sleet or rain for a time.

The all important mid-level circulation of the storm will pass from Ohio up through Lake Erie and then across Lake Ontario Sunday night and early Monday. This will put the band of heaviest snow from near Owen Sound to Pembroke, Ontario and then just north and west of Quebec City. The precipitation in the Windsor and London areas should stay mostly snow, but it will be wet as surface temperatures will hover above the freezing mark.

I will post the latest European long range weekly model stuff this weekend. It still looks quite cold compared to normal from the Northwest Territories and down into the eastern Prairies and eastern Canada, including the Midwest and Northeast U.S. during the second and also third week of December. The coldest air then retreats farther northwest toward the Yukon and Alaska by the fourth week of December.