Lake Effect Bands

General Discussions: ASK John: Lake Effect Bands

By snowlover_77 on Sunday, January 13, 2008 - 11:43 am: Edit Post

Hey John, I was just wondering what caused such a difference in lake effect bands. I am down by Fremont, and from your maps it looks like we are right on the edge of a primary band, but it seems that a lot of times we don't get as much snow as other places. I was wondering what causes the lake effect to be heavier up north of us and also south of us, but it seems to skip over us sometimes. Is it just the winds or what exactly causes the snow to be lighter around my area?


By admin on Sunday, January 13, 2008 - 02:57 pm: Edit Post

I am going to assume you mean Fremont MI.

There are a couple of reasons why both north of you and south of you do better with LES.

For areas to your north, it is because Lake Superior actually pre-conditions (adds moisture/heat) the air before it travels over northern Lake MI. Thus Lake MI does not have to work as hard to make LES.

For areas to your south, typically what happens is winds are north or north-northwest and travel a longer length of Lake MI before moving inland over areas to your south. Plus the lake is 35-40% wider south of you and thus in westerly wind events, there is more water for the air to travel over and create the LES.

-John


By snowlover_77 on Sunday, January 13, 2008 - 04:25 pm: Edit Post

Yes, I did mean Fremont, MI. Sorry I didn't clarify. Thanks for the info.


By chords on Sunday, January 13, 2008 - 05:19 pm: Edit Post

John, what causes the lake effect snow to form into tight bands or streaks as seen on satellite shots, prior to reaching land ?
And you mention about Lk. Superior pre-conditioning the wind before reaching Lk MI. Is that a big factor as to why NWL MI gets hammered with LES ?

Thanks
*chords*


By admin on Sunday, January 13, 2008 - 06:37 pm: Edit Post

Chords-

There are a couple of reasons and each reason produces a different type of band. When the surface winds converge, they cause the air to rise (like in the case of some thunderstorms) and when this happens during a LES event, you can get a convergence band of snow. This type of LES is very heavy, falling at the rate of several inches an hour. They are most common over lakes Erie and Ontario because those lakes are long in the east-west, but narrow in the north-south, so when you have a wind blowing down the long axis of the lake during a LES event, a land breeze can form on either side of the lake and cause the air to converge over the lake. Convergence bands do occur on all the other Great Lakes too. The southern 1/2 of Lake MI can have them occur quiete frequently because of it's shape.

Other types of banding that can produce streaks of snow is when you have what is called wind-parallel bands that develop. In this case, the wind is out of the same direction all the way up through the atmosphere that the LES is occurring. The air rises in all areas out over the lake, but because of factors like small scale convergence, you get the air to rise faster in some spots over the lake. Right next to this area of enhanced lift, you can have enough subsiding air to subdue the LES formation. Thus you can get banding to occur with the clouds and thus the LES that the banded clouds are producing.

This type of banding is most common on lakes such as Superior and Huron because of their shape.

Hope this made sense.

-John


By chords on Sunday, January 13, 2008 - 10:57 pm: Edit Post

Interesting, sure does. Thanks


By steelhead on Tuesday, January 15, 2008 - 09:42 am: Edit Post

Hey Snowlover 77.
Knew many Gerber people from Fremont. You don't happen to work there do you?


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