A cold front moved through the Midwest on Monday, October 13th and brought some heavy rain and much cooler temperatures to the region. On Sunday the 12th, Topeka, KS made it into the 80s but the high on Wednesday the 14th is only expected to make the low to mid 50s. The reason? A strong, classic October Cold Front. The image above and below shows where the cold front was at 8am on Monday (the blue line). I know that is where the cold front is by looking at two different features.
The first way to find a cold front is to find where the temperatures start to get cooler. On this image you can see that Missouri and Eastern Kansas have morning temperatures in the 60s. (the temperature is the number to the top left of each dot) Compare that to Western Kansas where the temperature in Goodland is 37 degrees. A cold front is in there somewhere, but where exactly is it? The cold front is the leading edge of a colder air mass. Wherever the temperatures START to drop off is where the cold front is located. On Monday at 8am, Manhattan had a temperature of 64 but Concordia had a temp of 46. The cold front is in-between these two locations as there is a 20 degree difference over a distance of only 60 miles...that's impressive!
Today you can find the front based on the drop in temperatures, however sometimes the temperature change is not as drastic and thus not as obvious. A cold front brings cooler temperatures, but it will also bring a change in wind direction. Usually a South wind will turn and come front the North. On this map the line coming off the dots represent the wind direction. Whichever way the line is pointing is where the wind is blowing FROM. The notches on the line signify how fast the winds are blowing, but to find a cold front you are only concerned with the wind direction, not wind speed. Notice how the winds across the "warm air" in Missouri and Eastern Kansas are from the South. The winds in Central and Western Kansas are from the North. When the wind direction shifts, that is when the cold front has passed, and that is when the cooler air will move in.
That's a quick and simple explanation on how to find a cold front on a weather map. This is a classic example today and the cold front is quite obvious. You will certainly notice it as it passes through.
Images are courtesy of www.rap.ucar.edu