Weather forecasting in USA.

One of the most curious things for me here is the weather forecasting. I started to check the maps almost a year ago and I'm still surprised about how fast the conditions change. The weather prediction is a really challenge here! Much more difficult to predict than in Europe. 
Here is an example for the following day forecast in Chicago: 

Friday: It will start to get warmer, but still NW chilly winds. -8ºC in the morning and around 1ºC in the afternoon. Sunny sky.

Sunday: Direct S wind from the Mexican Golf. Mild temperatures. Reaching the 10ºC barrier. Wet weather. Probably heavy rain.

Tuesday: N-NW winds again. The cold is coming back. Below cero temperatures very easily. Probably around -7ºC. No precipitations but not clear sky neither.
The best part is that by tomorrow or the following day the prediction will change drastically. 
Welcome to America!