Lake Effect Storms

Lake Effect Storm TypesWind/Shear Parallel BandsShore Parallel BandsShore basedMidlakeMesoscale Vortex

Lake Superior Lake Effect

Lake Ontario Lake Effects

Lake Michigan Shore Parallel Band

Lake Michigan Wind/Shear Parallel Band

10 and 13 January, 1998

Visible Satellite Loop Cloud rolls over water Spectacular Cloud streets over landEffect of lake shorelineGravity waves perpendicular to flow1704 UTC - 1748UTC

Characteristics of Wind Parallel vs. Shore Parallel Bands

Convective Boundary LayerRoll Convection

Instabilities Driving CBLOrganization

Growth of Planetary Boundary Layer Across Lake

Shore Parallel BandsWind blows roughly parallel to major axis of lakeAir warms from heat flux from water creating a strong land-water air temperature contrastLand Breeze is created forcing a land breeze front and meso-beta scale convergenceMeso-beta scale lifting of air to as high as 4 km AGL (compared to 1 km AGL for wind parallel bands) along land breeze front (s)Land breeze fronts usually combine into single convergence lineParallel to shoreline of lakePushed to downwind shoreline when winds are not completely parallel to shorelineDown center of lake when winds are exactly parallel to shoreline of lake

Shore Parallel BandsMost intense snows of all the different lake-effect snow types, because:Concentrates all of the absorbed moisture and heat along a single narrow bandMesoscale lifting deepens the system to several kilometers allowing precipitation processes to be more efficientColder than 20 CDeeper layer Bergeron Findeisen ProcessBands extend off shore and drop massive amounts of snow over small regionBuffalo, NY (Lake Erie, WSW wind)Gary, Indiana (Lake Michigan, Northerly wind)

Predicting Wind Parallel Lake Effect StormsLake temperature minus 850 mb temperature >13CWind fetch >100 kmWind speed moderate to high, i.e. >10 m/s

Predicting Shore Parallel Lake Effect StormsWind nearly parallel to long axis of lakeLake temperature minus 850 mb temperature >13C (can occur with less temperature contrast)Wind speed light to high, i.e. > 5 m/s