Snow squalls tomorrow: 1-2″ of snow with brief whiteout conditions possible

Our cold and wintry pattern continues, as the Polar Vortex remains entrenched in Southeast Canada, providing bitterly cold air. It also is the source for mid-level disturbances, as lobes of vorticity rotate counterclockwise around it, and drop southward towards the United States. This disturbance won’t gain a whole lot of separation from the vortex, however, which will allow it to get reabsorbed back into the vortex during the day tomorrow. This leads to the storm taking a track north of our area, back into southeast Canada, with a strong cold front out ahead of it. It is this cold front that will help to spark instability for snow showers and snow squalls — similar to how cold fronts during the summer provide instability for scattered showers and thunderstorms with locally heavy downpours.

Today's 12z NAM valid for 4:00pm tomorrow afternoon shows a mid-level disturbance rotating around the Polar Vortex, with some lobes or vorticity running out ahead of it in the Northeast. This will trigger some snow squalls. Image credit goes to weatherbell.com

Today’s 12z NAM 500mb forecast heights and vorticity valid for 4:00pm tomorrow afternoon shows a mid-level disturbance rotating around the Polar Vortex, with some lobes or vorticity running out ahead of it in the Northeast. This will trigger some snow squalls. Image credit goes to weatherbell.com

The system looks pretty robust in the mid-levels of the atmosphere, but since the storm system is not going to dig all that far south, it will not be able to obtain a significant moisture feed. Thus, widespread heavy precipitation amounts are quite unlikely. However, this does not mean that localized heavy bands of snow will not occur. The potent mid-level disturbance will still be able to generate the lift necessary for locally heavy snow squalls.

Today's 12z NAM valid for 4:00pm tomorrow shows a 986mb low in SE Canada, a very unusual track for snow. Image credit goes to weatherbell.com

Today’s 12z NAM valid for 4:00pm tomorrow shows a 986mb low in SE Canada, a very unusual track for snow. Image credit goes to weatherbell.com

What results at the surface is a 986mb low pressure system in SE Canada, with seemingly lackluster moisture. What is interesting to note, however, is the fact that we are getting snow with a low pressure system going well to our northwest. This is quite unusual, since strong low pressure systems in SE Canada usually advect strong southerly winds into the area, which helps to warm our temperatures significantly. As previously mentioned, most of the precipitation will come out ahead of a cold front — being ahead of a cold front is the warm side of one, which usually means warm temperatures.

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