If you are powerful enough, you can cast without anything other than your mind through visualization but take some time to learn about what is and what is not possible with magic.
And saying "blizzard" does not cause a blizzard to come any more than simply saying "ZetaStorm" causes me to appear.
If I say No7 Austine, does that tell you what I want you to do? I will need to add to that, find a way to contact you and tell you my intentions and if you are pleased with my request and you think it should happen, and it is possible, then you may carry out my wishes. Magic works also in this way.