Thursday, January 1, 2015

January 5-6 Potentially Significant Clipper Snowstorm

Model guidance is starting to realize the potential for a rather significant clipper storm in the January 5-6 period.

Instant Weather Maps
The above image shows the 0z GFS snowfall projection for this clipper storm over a 24-hour period, ending on the afternoon of January 6th. We see a very strong clipper system dropping snowfall in the range of 6-10" across eastern Iowa, southern Wisconsin, and northern Ohio into Michigan. Northern Indiana and Northern Illinois are hit especially hard, with a stripe of 9-10" accumulations. The clipper then goes on the drop amounts over 6" in northwest Pennsylvania, with additional shovel-able snow spreading across New York and other portions of the Northeast.

Instant Weather Maps
Let's fast-forward to the most recent GFS forecast, which is the 12z forecast. In this 24-hour snowfall accumulation chart, valid for the early-evening of January 6th, we see high snowfall amounts over the eastern Dakotas into Minnesota and Iowa, extending far into Wisconsin, Illinois, Indiana, Ohio, and the Northeast. Here, the hardest-hit regions look to be eastern Iowa into northwest Illinois, where amounts are maximized to the 8-10" range.

I'm unable to share certain graphics of other models on this website due to copyright concerns, but it appears the Canadian GGEM model does not have this clipper system. However, the ECMWF model does have this clipper potential, with a decent amount of GFS ensemble members also backing the solution. Regardless, there's quite a bit of uncertainty here.

To summarize:

- Model guidance is indicating a strong clipper system may strike the Plains and Midwest to start the next workweek.
- Amounts off of one model point to maximum 6-10" accumulations.
- High uncertainty still exists with regards to amounts, storm track, and even the existence of the storm.