Lake-Effect Snowstorms

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Amount of snow from lake-effect snowstorms

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Can produce 1-5 ft of snow in a single event, with snowfall rates exceeding 1 inch/hour

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Key ingredients for lake-effect snowstorms

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Polar/Arctic continental airmass over warm lake water, wind blowing over lake axis, unstable atmosphere over lake, topography downwind of lake

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Prevailing wind directions for Western and Eastern Great Lakes

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Western lakes: North wind; Eastern lakes: West wind

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Process of lake-effect snowstorm development

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Cold air moves over warm lake water, increasing SVP and moisture transfer, creating unstable air and clouds, with heaviest snowfall at shore

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Range of lake-effect snowstorms

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Extend inland 50 to 80 km (30 to 50 miles) downwind of lakes

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Fetch

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The distance an air parcel travels over water

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Stages of Lake Effect Snowstorm Organization

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Wind Parallel rolls, shore parallel bands, vortices

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Wind-Parallel Rolls

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Light, widespread snowfall with strong winds and short fetch, multiple bands, updrafts, and downdrafts

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Shore-Parallel Bands

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Heavy, localized snowfall with weak winds or wind direction along long axis of lake and strong to moderate winds

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Vortices

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Moderate, localized snowfall with weak winds, cyclonic flow around vortex, spiral snow bands, and 'eye'