Tuesday, October 11, 2011

Prospects for Snow in Midwest/Ohio Valley Rising as ECMWF Joins Snow 'Camp'

Pre-Reading Notes:
Vocabulary: 'Camp' is a term you will hear often this winter if you read this blog frequently. In the weather enthusiast world, a 'camp' is defined as a group of models favoring one solution to a weather event over another group. Example: The ECMWF/GFS models are in the snow camp vs the GEM model in the rain camp. In the example, the ECMWF/GFS are favoring snow for an area versus the GEM model favoring rain for the same area in the same time frame.
(end pre-reading notes)

The ECMWF has joined the camp of models favoring a cold blast following a strong low pressure system. In the midst of that cold blast, some precipitation may still be ongoing on the back of that low, introducing the seasons first snow flurries for the region. Here's the latest 12z ECMWF model.
Hour 192 (October 19)
The top right image is the one of most importance. The dashed red line sinking down below the Great Lakes region is referred to as the 540 line. It is basically the line where, theoretically, rain switches to snow for areas north of the 540 line. Another dashed line farther south isn't something we need to worry about.
The 12z GFS is now predicting a slightly higher amount of snow for cities like Chicago and Gary, IN for this 12z run. Below is the predicted snow depth for Hour 192- the same timeframe as the ECMWF image above.
The GFS is predicting as much as over an inch of snow to fall in areas close to Lake Michigan extending eastward into Ohio, Michigan and even into New York. Below is the GFS's take on the 540 line.
The blue area is considered the air north of the 540 line, so the separating boundary/540 line is the green/light blue border on the map above.

What do we expect from this system? We really don't want to say much as it is still a while off and winter weather is harder to forecast for the models, but as of right now, the areas above are looking at a fairly good chance for snow for the time being.

No comments: