More on the cold airJanuary 16th, 2013 at 11:19 am by Greg Shoup under Weather
This is some of the coldest air I’ve seen for this area in many years. The reason my antennae were lifted up is because we have not seen the “Polar Vortex” or core of the coldest air around these parts in several years. Here’s what I’m looking at in the weather center.
Okay, I know this looks like it’s written in Chinese but bare with me here. This is a chart that shows the ‘thickness’ of the atmosphere. Thickness is the best way, especially during the winter, to show what the temperatures will be. Keep in mind that the 540 line is usually where we begin to think of freezing. So I labeled a couple of these areas for you. The 500 thickness line is usually where we begin to forecast zero degree Fahrenheit temperatures. Well, on January 22, which is Tuesday we are measuring 497 thickness. That means in the pure sense we would see below zero temperatures.
This is the air which is 4,400 feet above the surface. It is a good source to see the area between upper air and surface temperatures. This is a Celsius measurement of -28. (-18.4 F). This is an upper air temperature but it does show how deep this area of cold air is. We know from our basic science class that the cold air sinks to the surface and in this situation we are seeing that the cold air is also supported by extremely cold air above it.
The Lake Michigan water temperatures are also rather warm and the trajectories are showing winds out of the northwest which would bring on a heavy Lake Effect Snow event for areas close to the Lake. We could also see some snow from this event across our area.