I've quickly learned one thing about winter weather. Snow is the hardest forecast that there is. There's just a lot that goes into what happens. Not only that, but relating it to you is tricky as well. There are times when we know there will be a significant snowfall but where it will happen is still in question.

Think about this. During the summer months if you hear rain is in the forecast for tomorrow, typically you will just grab the umbrella and brace for a wet day. More often than not you're not concerned if we're gonna see a tenth of an inch or a inch as long as flooding isn't possible. When it snows there are a lot more questions. Even I want to know when it will start, how many hours it will last, and when its done how much snow will be on the ground.

Really these are all tricky questions and I enjoy answering them (especially when I'm right!). Usually it is hard to determine a start point for a snow event other than giving a 6 hour period until about 48 hours before it starts. Even more so determining when it will end can be trickier because it seems that snow likes to fall for a much longer time than rain does.

With timing being very important its never what I stress over the most. Amount of snow is where I always put my emphasis when forecasting. It is with out a doubt one thing that you can walk out to your back yard, measure, and decide if I am wrong or right. The reason I find it so difficult is really for two reasons.

First off, the location of where the heaviest snow will be can be a hard forecast. There have been times this winter when the heaviest snow is over Iowa when they were calling for six plus inches. At the same time, we typically called for a dusting here, but we had our eye on those storms. Any little shift and we could see many more inches of snow.

The other issue is what we call snow ratio. Snow is just a form of precipitation. It starts the same way rain, hail, and sleet form. A snowfall amount starts as just a liquid equivalent. You'll typically find that 1 inch of snow is a tenth of an inch of water when melted (a 1:10 snow ratio). So once we decide on an amount of liquid we have to analyze the entire atmosphere vertically (from the surface to the top) so we can make a ratio. This can vary from 1:10 to 1:20. That could mean a difference of 6 inches or 12 inches in your driveway to shovel depending on which end of the ratio we end up on. The snow ratio affects the consistency of the snow. The higher the ratio the fluffier the snow will be.

So there's lots of work that goes into a snowfall forecast so that you can know the timing, amount, and consistency of the snow. Although it can be difficult I really enjoy the challenge. With all this said, maybe the next time there's a few more inches of snow in your driveway than expected you'll understand. Maybe you'll not blame me as much while you're at it.