Sam Brandt

Wednesday, October 18

Everyone in PA knows by now that this fall has been much warmer than normal. In fact, it's been so warm that this October has a decent shot at being a record setter. The well above-average temperatures have also left the waters of Lake Eerie at temperatures they haven't been at this time of year since the mid 1980's (63-67 degrees F). 

You may be asking how above-average lake temperatures could lead to more lake effect snow and clouds. It's certainly a valid question to raise. 

To answer the question, let's first break down what exactly the lake effect is. Imagine a large body of water in early winter, when water temperatures are still significantly warmer than the ambient air. This happens because water has a higher specific heat capacity than air (i.e. water gains and loses heat at a much slower rate than air). Let's now imagine that an arctic cold front has blasted through, and a very cold wind begins to blow from one shore of the lake to the other. As the wind is blowing over, the warmer waters heat and saturate the air just above it. Now a temperature gradient has been created, and the warmer air rises through the cold air above it, where its water vapor condenses to form clouds. These clouds are then carried by the strong winds offshore and inland, where they precipitate.

Now let's apply our newfound knowledge of the lake effect to current trends. The above-average temperatures in the waters of Lake Eerie will allow for larger temperature gradients to form over the lake this winter when those strong northwesterly winds begin to kick in. Larger temperature gradients mean more instability, and more vigorous convection to fuel snow squalls. 

So when that first deep trough cuts into PA this winter season, and the winds begin to kick up, don't be surprised to see clouds and snow on the way.

Bold words indicate terms that curious readers might want to research further