View Full Version : Light vs. Heavy LES

01-11-2008, 11:29 AM
So what conditions make for a heavy LES event vs. a lighter LES event? Is it just the very cold air and a NW to SE flow? The colder the air the more the LES?

01-11-2008, 03:54 PM
There are a number of factors. In a nutshell what you want is for the LES clouds to grow to the highest level they can. That allows the clouds to produce heavier precip.

Factors which allow the clouds to grow are things like how unstable the atmosphere is. How dry the low level air is, how strong the winds are. The fetch (distance) of water the air can travel over. Low level convergence of the winds.

So it is not purely the colder the air the heavier the LES. In fact it can get so cold that the air is so dry that the les is actually pretty light.


01-11-2008, 04:05 PM
Thanks John. BTW, love the site. So much in one place for the sled world. We head up to the UP from MN at least 3 or 4 times a year, and because of your great snow, and fabulous trail system, me and the buddies have actually gotten the wives and kids to enjoy it as well.

Sounds like LES is something more complex than an average guy like me really can understand, but I'm hoping that LES spigot is turned on high next week like you've thought is a possibility. Heading up there on the 17th, and hope the long weekend is full of lots of fun!


01-11-2008, 05:50 PM
zimmbob - Heres a good explanation of LES. I still wonder why LES forms into heavy localized bands instead of a more uniform snowfall upon reaching land.

LES Basics (http://www.islandnet.com/~see/weather/elements/lkefsnw2.htm)

01-13-2008, 02:56 AM
I noticed the arrowhead of MN had heavy LES today. I imagine that's pretty rare.

01-13-2008, 03:47 PM
Yes it is. Not unheard of, but they have a decent LES event happen only once or twice a year on average.