Wisconsin Weather

Forecast Discussion - New Years Eve Snow

By Justin Poublon
December 29, 2018 - 4:30 PM CST | 396   0

The main narrative is that there is a chance for snow statewide on New Years Eve. Freezing rain could be involved. For this story I will discuss only the snow chances. There could be several inches of snow accumulation on the ground New Years day...or not...depending on your exact location. Pretty confident on far northern Wisconsin for places like Ashland and Bayfield counties, just waiting for other places to become clear. There is considerable model disagreement at this forecast hour especially across the southeast half of Wisconsin.

Sometimes we can forecast snow chances eight days ahead of time. Other times we have a hard time telling just two days away. Our current situation is the latter. Lets take a look at the models and I'll explain why.

Model Snowfall Forecasts

For Monday some of the best performers have conflicting predictions. Tonight's model run could bring all models to a consensus or continue the stalemate right up until the event starts? With out-of-phases systems like this it's always a tough forecast. You have to wait it out. Here are what the current predicted snowfall amounts are for each model by Tuesday morning:

Canadian

Wisconsin Weather
6" of snow across the far north with a large region of 1-3" in eastern and southern Wisconsin. Lower amounts in Eau Claire area.

GFS

Wisconsin Weather
The latest GFS is more narrow and further south with zone of snow accumulation. Lower amounts for much of central Wisconsin. Still at least some snow.

NAM

Wisconsin Weather
NAM is further north placing 2-4" across northeast Wisconsin and much lower amounts in the northwest. Barely a trace in same place there is 3" on the GFS.

Euro(EC)

Wisconsin Weather
The Euro(EC) which is regarded as the best model in the business is definitely more snowy for southern Wisconsin and has been the last two runs. NOTE that this is snow depth, not accumulation. This is at odds with the rest of the models. Would you sell out for the Euro? I wouldn't.

Conclusion

Which model is correct? I don't know yet. Have to wait it out. It takes a human forecaster to interpret all these models, understand the tendencies, then make the final forecast. Personally I believe you have to play it fair and remove bias. One model will be correct on location but not amounts. Another model will be perfect on amounts but not location.

With this situation I simply want to communicate the chance for snow. The challenge is normally I would lean away from 3"+ totals in southeast Wisconsin if not for the Euro. Normally I would plan on 6"+ in Ashland county if not for the NAM. So I will plan to wait. "Chance of accumulating snow" covers it. I can add in snowfall predictions later (perhaps as early as tonight?) when we have some consensus.

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