Snow Forecasting

Introduction

Snow is perhaps the most critical one- to two-day forecasting challenge for the National Weather Service. Unlike severe weather, which can at best be forecasted a few hours ahead, snow is in principle forecastable several days in advance. Furthermore, the public needs accurate snow forecasts a day in advance, in order to plan (or cancel) auto or plane trips, or get snow removal equipment into position.

For the Weather Challenge, snow is irrelevant. Precipitation is precipitation, whether it's rain, snow, ice, or drizzle. But when it's going to snow, it's sometimes easier to envision how much snow will fall (3 inches, a foot, etc.) and then convert it into the corresponding amount of liquid water for your precipitation forecast. Also, certain weather phenomena that produce snow are associated with cold environments, and you must understand how these work in order to make precipitation forecasts in cold weather.

Learning Objectives

  • To understand the Bergeron Process of precipitation formation
  • To be able to forecast precipitation type: rain, snow, freezing rain, and sleet
  • To understand and predict lake effect precipitation
  • To be able to estimate the liquid equivalent of snowfall

Table of Contents

  1. Making Clouds
  2. The Bergeron Process
  3. Precipitation Types
  4. Upslope Flow
  5. Lake-Effect Snow
  6. How Much Water is in Snow?
  7. Summary

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