1. Lake Effect Storms

2. Lake Effect Storm Types Wind/Shear Parallel Bands Shore Parallel Bands –Shore based –Midlake Mesoscale Vortex

3. Lake Superior Lake Effect

4. Lake Ontario Lake Effects

5. Lake Michigan Shore Parallel Band

6. Lake Michigan Wind/Shear Parallel Band

7. 10 and 13 January, 1998

8. 1704 UTC - 1748UTC Cloud rolls over water Spectacular Cloud streets over land Effect of lake shoreline Gravity waves perpendicular to flow Visible Satellite Loop

11. Characteristics of Wind Parallel vs. Shore Parallel Bands

12. Convective Boundary Layer Roll Convection

13. Instabilities Driving CBL Organization

14. Growth of Planetary Boundary Layer Across Lake

15. Shore Parallel Bands –Wind blows roughly parallel to major axis of lake –Air warms from heat flux from water creating a strong land-water air temperature contrast –Land Breeze is created forcing a land breeze front and meso-beta scale convergence –Meso-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 line Parallel to shoreline of lake Pushed to downwind shoreline when winds are not completely parallel to shoreline Down center of lake when winds are exactly parallel to shoreline of lake

16. Shore Parallel Bands Most intense snows of all the different lake-effect snow types, because: –Concentrates all of the absorbed moisture and heat along a single narrow band –Mesoscale lifting deepens the system to several kilometers allowing precipitation processes to be more efficient Colder than –20 C Deeper layer Bergeron – Findeisen Process –Bands extend off shore and drop massive amounts of snow over small region Buffalo, NY (Lake Erie, WSW wind) Gary, Indiana (Lake Michigan, Northerly wind)

17. Predicting Wind Parallel Lake Effect Storms Lake temperature minus 850 mb temperature >13C Wind fetch >100 km Wind speed moderate to high, i.e. >10 m/s

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