I, like so many of you, watch the lake surface temps. I hope for temperatures to drop into the 50s so the salmon will come to shallow water. During the time that I have been watching lake temps I notice an interesting occurrence temps at the surface several miles off shore dropping to the 40s. First I thought that these must be false readings caused by some phantom equipment malfunction, but I continued to notice them and what seams to be a loose pattern.
It seems that a day or two after we have heavy winds and storms these cold "spots" appear on the surface. The geek in me wanted to know why. 
Was it the influx of rain water from the rivers, was only a portion of the lake doing the notorious "flip" I didn't know.
So I started some investigative work.
I'm was thinking lake currents could be one cause, pushing the cold water up from the depths, an upwelling. As I searched the web I ran across a video about stratification which is fancy for the layers in the lake, three layers to be precise. I'm not gonna go too deep here you can learn like I did through the video. But the interesting part is that the density of water causing these layers relates directly to temperature. It is the dividing factor, and the dictating factor in the thermocline. Which is located in the center layer of the three.
Deep water fishermen take note if you aren't already informed. Winds push warmer surface waters towards the shore where the depth of this warm water "builds" basically tilting the layers and the thermocline. Bring it closer to the surface at the other end of tilt. As the wind stops the water driven towards the shore recedes like water in a tipped bucket returning upright. It then rocks back and forth under the surface each rocking motion tilts the layers and the thermocline AND mixes the layers.
That is an important factor in these upwellings as it mixes and rocks warm surface water seems to roll to the bottom under the force of the wind as this happens cold water is driven to the surface in an upwelling.
If we agree that the fish follow the thermocline and these cold water upwellings knowing where they are can hugely effect finding fish.
Coho prefer temperatures in the mid-50s F. and generally are found nearer the surface than chinook. After 60 degrees F. coho tend to go deeper or lakeware in finding their preferred temperature. Coho may be found in water temperatures from 45 to 60 degrees F., with a peak feeding temperature at 54 degrees F.
I think most experienced boat captains already know this, but for a weekend warrior learning this can be helpful as opposed to going where the other boats go.
The implications of these things for a shore and pier fisherman can be figured as well. I'm sure hydrology has some wicked formula for calculating how long it will take for the rocking motion to occur given an average sustained wind and the size of a body of water including depth. Please hydrologist help us understand.
There is another thought that comes to my geek head. How the salmon move may be less tied to water temp in itself and more tied to food. Thus it may be less important to know what temp the salmon like and more important to know what temp their food likes.
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