Lake-Effect%20Snow

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Lake-Effect Snow
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Lake-Effect Snow Occurs

• Mainly in the Great Lakes region of the U.S.
• Great Salt Lake in Salt Lake City, UT
• East side of James Bay
• Always on the downwind side of large lakes

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Synoptic Setup
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Necessary LES Conditions

• Need lake temps to be warm compared with air
  temperatures over the lake
• The lake cannot be frozen.
• A temp difference between the air at 850 mb and
  the water surface of at least 13C

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Time over Water
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Influential Topography
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Satellite Image of LES
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LES Climatology
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Why Winter Months?
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Wind-Parallel Bands
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Examples of Shore and Wind-Parallel Bands
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More Examples
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Lake-Effect Vortices

• Still being studied!!
• Related to horizontal shear?
• Wind speed?
• Topography?
• Stability?
• Sometimes have an eye
• Diameter
• 10 to 100 km

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December 2001 Christmas in Buffalo

• Over 70 inches of snow fell in a 5-day period
• Shore-parallel band headed straight for Buffalo,
  NY

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Forecasting LES

• Models usually dont resolve LES. Why?
• Not fine enough resolution to capture.
• So what do we need to look for?
• Temperature difference between air at 850 mb and
  surface of lake is at least 13C
• Direction of wind
• Persistence of synoptic conditions
• Is there snow already falling?
• Any mesovortices