Clipper Snowfall Forecasts Lowered

48 Hour Snowfall Accumulation
Centered on Brainerd, Minnesota.
Image from Intellicast's SNOWcast.

48 Hour Snowfall Accumulation
Centered on Chicago, Illinois.
Image from Intellicast's SNOWcast.

Snowfall Forecasts for the Alberta Clipper are lowering, as shown by Intellicast's SNOWcast 48 hour snowfall accumulation forecast above. It looks like the maximum totals will actually turn out to be around 1-2 inches for South Wisconsin, with up to 4 inches in Minnesota from this clipper. I am not surprised, as it takes a lot of moisture for 4 inches of snow to fall, especially for an Alberta Clipper, which is moisture starved to begin with.

Clipper System to Lay Down Up to 6 Inches of Snow

Maximum Possible Totals Shown

A clipper system is expected to lay down up to 6 inches in some spots of the Northern US in the next couple days. While 6 inches is unlikely, this is a maximum snowfall accumulation map.
Some notes on the map:
-Some light accumulations may occur a bit farther south than what the accumulations show above.

Signs Appearing that +AO/+NAO Regime May Break

Initial 0z ECMWF 500mb Analysis

Above we have the initial 500mb heights analysis from the latest 0z ECMWF. We see the tight polar vortex of low atmospheric pressures encircled in the black area. This polar vortex is what supports the +AO/+NAO regime. That said, if there were high pressure systems over the same black area, we would be seeing some sort of -AO/-NAO. Let's jump ahead into the ECMWF's forecast.

Hour 192 of 0Z ECMWF

At hour 192 we're seeing the Polar Vortex break apart as a ridge forces itself into the vortex from Asia. This in turn forces a low pressure system towards Greenland, making for a West Based +NAO. While we aren't showing it, this ridge does break down at the end of the ECMWF forecast timeframe. It does show that there is potential for a ridge to break in and possibly bring in some colder weather for the US.

This is another view of the top 2 images, with the analysis period at the top and the hour 192 image on the bottom of these latest 2 images.