Sunday, November 9, 2014

November 8-12 Significant Snowstorm - Final Update

This is the Final Update for this significant November 8-12 snowstorm.

Winter storm watches (dark blue) and warnings (pink) have been hoisted across a swath of the Upper Midwest into the Northern Plains, as a strong storm system looks to push south into the US and create a potentially dangerous environment for those caught by surprise from this storm. Winter weather advisories (purple) have also been issued for areas where the storm will strike earlier, compared to those in the Midwest.

Tropical Tidbits
The image above shows the GFS model's forecasted total snowfall from this storm over the next 4 days. We can see how the storm is forecasted to lay down amounts near 12" in the Northern Plains, before unleashing on the Upper Midwest. The yellow swath shows amounts in excess of 18" of snow, while those brown-ish areas depict amounts close to two feet of snow. Going by this forecast, we would see the brunt of the storm strike central and northern Wisconsin, as well as the Upper Peninsula of Michigan. Significant amounts would still impact portions of Minnesota and the Dakotas, but Wisconsin would receive the heaviest totals.

Tropical Tidbits
We'll next look over the forecast from the GFS-Parallel model, the newer version of the GFS model which will replace the current model in coming months. This GFS-Parallel model is rumored to be more accurate in multiple aspects of its forecasts, and this storm looks to be its first real test. The GFS-Parallel shifts the bulk of the snow east, now slamming the Upper Peninsula of Michigan into south-central Canada with those two-foot totals. Amounts in Wisconsin would still near 24", but not as widespread as the current GFS model shows. Minnesota is also forecasted here to receive heavier snow, extending into the Dakotas as well.

Regardless of which model you're looking at, the picture is clear: this storm will bring very heavy, very early-season snow to the Upper Midwest and North Plains.

The Weather Prediction Center issues probabilistic forecasts for snowfall amounts in a given period. In the above image, we see the WPC's forecast for the likelihood of 12" of snow falling in a 24 hour period, centered around November 11th. The WPC places the likelihood at around 50%, a value that's likely to rise as we get closer to the storm's impact and confidence increases.

To summarize:

- A significant winter storm is forecasted to affect the North Plains and Upper Midwest.
- Amounts nearing 24" may be expected, especially in Wisconsin and the Upper Peninsula of Michigan.
- Preparations for this storm should begin now.


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