Hey Everyone,
Sorry for not posting sooner, I was extremely tired last night and went straight to bed without updating. But I am here for a significant update.
Winter Storm Warnings, Winter Weather Advisories, and Flood Watches have been issued for portions of the region. Temperatures have been generally in the mid 30's, however recently here in the Champlain valley, winds have turned due north, and in Swanton Vermont, the temperature had dropped 10 degrees in 13 minutes. (39F - 29F) So the cold front has definitely moved through the area. Cold air is being ushered in upon a brisk north wind.
Now to the forecast of this extremely complex, headache of a storm. This is one of those very hard storms to forecast, all dependent upon how much cold air is entrenched at the surface, and how thick the layer of cold air is. I will guarantee this, everyone will see some frozen precipitation at some point, even in the south, however I feel mainly rain is going to plague the southern areas, and very well produce significant flooding. So this is how it breaks down, precipitation is already ongoing across Southern Vermont and New Hampshire. Falling as mainly rain in NH, and a mix of sleet, freezing rain and plain rain across Southern Vermont. Cooler air is in the process of making its way down to that region. So the rain should change to more sleet and freezing rain as we get into the evening. Now for this area, it will not be long lived at all, because warm air will once again move north warming up temps across Southern Vermont, and Southern New Hampshire. Changing the freezing rain back over to plain rain. Across Central Vermont, and Central New Hampshire precipitation will start between now, and 6PM as snow/ sleet, changing over to freezing rain, this area will have a longer period of freezing rain then southern areas. Across Northern New York, Northern Vermont, and Northern New Hampshire, precipitation will start between 6PM and 11PM, as snow changing to snow/ sleet, then to sleet/ freezing rain, and eventually to all freezing rain. These northern areas are the most likely to see significant ice accumulations, at this time the entire Champlain Valley, remains a toss up between an ice storm or rain storm. At this point I don't see enough cold air remaining in place for it too be much of an ice storm, but once again it all depends on how strong, and lasting the northerly drainage flow into the valley lasts. Right now its a 55% chance of being mainly rain within a few hours after onset and a 45% chance of being an ice storm. Its too close to comfortably call. But I am painting in on the precipitation type map, mainly rain for the Champlain Valley as of right now.
For northern New York, excluding the Champlain valley, a very significant ice storm looks likely, with up to one inch of ice possible, across the St. Lawrence Valley. Cold air may never be pushed out of the St. Lawrence valley during the duration of the storm, causing the potential for that much ice. This is beginning to look like a dangerous situation. Any ice accumulation over a half inch could lead to falling tree limbs, and snapping power lines, causing the potential for widespread power outages. Persons across all of Northern New York, Vermont, and New Hampshire should pay close attention to this storm system, but of most concern are persons across Northern New York, and the St. Lawrence Valley.
Now that we have the ice situation addressed we will switch to the snow aspect of this storm, mainly on the back side, and highest accumulations in the higher elevations, and western slopes of the green mountains where up to 5 inches of snow could accumulate. Southern areas will see a Trace to 1 inch and northern areas 1 - 2 inches. Below are the maps of dominant precipitation types, ice accumulations, snow accumulations, current National Weather Service Alerts, and then the map of what I feel should be issued for alerts...
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