Is this still having an effect on our weather system? And if so, how?
There have been over a hundred tornados in Kansas, alone so far this year and it's only May
How did it change the weather then and how is it affecting us now?

Try the NOAA El Nino Page. There are several good links, including Today's El Nino / La Nina Information.

Thank you very much

There does seem to be a correlation between warming and cooling cycles in the Pacific (El Nino/El Nina) and the number and intensity of tornadoes in th US. The data show however that it not the warm cycle (El Nino) that bring more activity rather it is the cold phase (El Nina.)

See: THE RELATIONSHIP BETWEEN EL NINO, LA NINA, AND UNITED STATES TORNADO ACTIVITY

Looking at the chart in Figure 1 from the above link you can see that the number of tornadoes in the US has steadily increased over the last 50 years or so and this could be attributed to one of the Potential Effects of Global Warming.

Thank you, Miles. That's a very interesting site.