An Icy Mess or a Rainy Mess?

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Our streak of snowstorms is coming to an end this weekend. Even with 10″-30″ of snow on the ground across the state it’s not out of the question we’ll be dealing with rain on Sunday. How can this be!?

A powerful shot of Arctic air with sub-500dm thicknesses is once again plowing into the Lower 48. This shot will be accompanied by a near 1050 mb high over the northern Plains. Instead of crossing the international border near the eastern Great Lakes this one will be much farther west. To the north of New England there’s no cold high pressure or confluence aloft to shunt a storm system underneath us.

Instead, we’re left with what will likely be a cutter.

Cutters come in all shapes and sizes. Some cutters are weak enough that they only bring light rain after some initial snow and icing. Weak ones like the GFS shows for this weekend would bring a bit of everything with temperatures that struggle out of the low 30s.

The Canadian model (which has had a good winter) forms a more powerful low that cuts well to the west and brings temperatures well into the 50s!

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While not the most likely scenario this is certainly possible! Snow cover will do nothing to keep the storm from cutting well west with no high to our north and no mechanism to suppress the storm track. What is concerning about this setup is that the storm is strong enough near Buffalo to bring a sizable push of warm air in and would start rapidly melting snow. Flooding issues and roof collapses would be the likely result – especially toward Boston.

While deep snow pack can help maintain a cold surface with a weaker storm system that cuts to the west – a stronger storm (driven by mid-level processes and almost totally independent of snow depth) could care less about a couple feet of snow on the ground. Rain to Montreal!

This certainly has happened before. The epic January 1996 cutter resulted in some of the most incredible snow melt we have seen. It is a blight on what was otherwise a fabulous winter.

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As for what will happen with this storm I think odds favor a weaker storm (more like the GFS) which would bring a period of snow followed by icing with temperatures in the low to mid 30s. Ground temperatures are cold enough that ice would be an issue on the roads. Most of the GFS ensemble members show this kind of scenario.

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Bottom line – watch forecasts for this weekend closely. A bit of snow, ice, and rain all appear likely. Hopefully we can avoid getting a big thaw in here – a more gradual thaw is definitely preferable!

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