What's wrong with my transmission?

I have a 1992 Chevy Lumina 3.1L, 92K and before today I had no issues with the transmission. I live in upstate NY so the last week or so we have gotten a ton of snow and I've been driving through it. As this is my first winter with the car I was pretty impressed with how powerful it was in the snow. However this morning when I put my car in drive once i get over 25 MPH (1st gear) it doesn't go into second but seems to be back in neutral? Any advice? Am I screwed?