Another LES Question

General Discussions: ASK John: Another LES Question

By chords on Saturday, December 27, 2008 - 01:27 am: Edit Post

I watched a local "winter weather" show in MI. They claimed that the Grt. Lks LES bands can stretch out and carry snow and moisture and affect the weather as far south as Georgia and the Carolinas and everywhere in between which may be Hundreds, maybe a Thousand miles away and that it's not considered LES but is called Upsacale caused by the Applaichian Mountains.

I guess any extreme is possible in a 100 year span but can or does this really happen very often ?


By admin on Saturday, December 27, 2008 - 08:33 am: Edit Post

Chords-

It's a bit of a stretch to say that the Great Lakes have an influence in the weather in places as far away as Georiga and the Carolinas. The mechanism you talk about is "upslope". That is the forcing of air up due to a change in elevation and is the big reason why the mountains out west get so much snow and also to a lesser degree the Appalachian mountains.

Even here in the Midwest, the higher terrain downwind of the lakes can cause a bit of upslope. That is the main reason why downtown Marquette sees less than 150" of snow annually, but less than 10 miles to the west, Negaunee and Ishpeming see closer to 185-200" annually.

The residual moisture from the lakes can be lifted orographically (upslope) in areas like West Virginia, PA, NY and into New England, but areas like GA and the Carolinas are likely too far away for any residual moisture to make it. I suppose in an extreme case, there might be a tiny bit, but not enough to be considered part of their climatology.

-John


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