Frequently asked question: Why does my weather app say that I’m getting 20-30 inches of snow? This one is a pretty straightforward answer. Most phone weather apps rely completely or heavily on automated output from one or a few computer models. Those models spit out exact numbers — even when there is a significant degree of uncertainty in the forecast — that often fluctuate throughout the day, even by the hour. Human meteorologists, on the other hand, compare multiple models, account for known model biases, and know which models are best for which weather situations and time ranges. They also factor in local nuances that models can’t resolve, and try to filter the model fluctuations out of the forecast. Don’t get us wrong. Weather apps can be useful and convenient to plan your day or week when the weather is quiet, or when there is particularly high confidence in inclement weather within a day or two. But when the weather gets more complicated — especially as complex as predicting snow, sleet, freezing rain, and the dividing lines between them — nothing beats the expertise and local knowledge of an actual human meteorologist.