1. Forecasting Lake Effect Snow Storms
By: Jake Mulholland and Michael Vuotto

2. Lake-Effect Season
Begins around November
Ends around March

3. Ingredients for Lake-Effect?
Cold, arctic air flowing over relatively warm lake surfaces
Low And Mid-Level Moisture
Favorable wind direction and speed
Long fetch

4. Lifting Mechanisms? Orographic lift (ex: mountains, ridges, etc.)
Frictional Convergence (ex: faster lake winds hitting slower winds along shoreline = lift!!!)
Thermal Convergence (ex: land breezes when lake is much colder than land surface)

5. The magic “13”
Look for surface water temp.  850-mb temp. difference of at least 13˚C (may vary by elevation; ex- Great Salt Lake)
Allows for good instability to develop and lake-bands to form

6. Capping Inversion
The “capping inversion” is basically the layer at which the air dries out and the temperature warms with height
For lake-effect we want it around 850mb or higher (ex: 800mb or 750mb is very good)
Capping Inversion around 725mb (good for lake-effect)

7. Moisture
You want lots of low-level moisture for healthy lake-effect snow
The warm lake provides lots of moisture as cold, arctic air flows over it
Warm lake is truly the “driving force” for lake-effect

8. Wind Direction and Speed
Favorable wind directions at 850mb (steering height) for Oswego = Around .. ??
Tug Hill .. ??
Fulton .. ??
Syracuse .. ??
Favorable wind speeds for a heavy, single band of lake-effect is usually between kts from the surface to 850mb
Also, little change in wind direction, <30˚ from surface to 850mb, is favorable = want them to be fairly uniform!

9. Fetch Distance cold, arctic air flows over warm lake waters
Minimum threshold for flurries: around 80km
Minimum threshold for significant lake-effect snows: at least 160+ km

10. Lake-to-Lake Connections
Upstream lakes such as Lake Huron, Georgian Bay, etc., can provide additional moisture and boundary-layer instability  HELPS OUT THE LAKE EFFECT!!

11. Synoptic Set-Up
Areas behind _______ ______ (2 words) are favorable for lake-effect
It is good because of the low-level, cold air advection behind it
Also, cutoff lows that sit north of Lake Ontario are favorable for lake-effect snows due to the WNW/W win component to the winds

12. LLAP Bands
What does LLAP stand for … ???

13. LLAP Bands YES! = Long-Lake Axis Parallel Bands
Typically follow the southern shoreline of Lake Ontario (which is where they got their name)
Most intense types of bands
Can drop 3-5” of snow per hour
Ex: look at the flyers outside (2007 LLAP band that dropped 3+ feet in Oswego, NY)

14. Mesocyclones, waterspouts, etc. in Lake-effect snow storms … ???

15. Other types of lake-effect snows
Multiple snow bands
Hybrid Snow bands
Mesoscale Vortex bands (see below)

16. Tools for forecasting these events
RAP weather: good for surface maps and model data
King City, Ontario Radar: good for detaching any upstream connections
BUFKIT: GOOD IN GENERAL!!! (especially magic “13” number)
GARP: useful to look at 850mb temps and winds
HRRR model: high resolution model data (look at forecasted composite reflectivity, winds, etc.)

17. WRF-modeling of Lake Effect Snows

18. Opportunities?
We here at Oswego have done a lot in terms of Lake-Effect Snow studies
Ex: Winter of Lake-Effect Snow EAGER Grant Research with the Doppler-on-Wheels

19. Future Opportunities …
OWLeS (Ontario Winter Lake-effect Systems) $320,000 grant!
3-yr grant that will encompass the following equipment:
Mobile weather stations
Rawinsondes
3 DOW’s (one of which is the Rapid Scan DOW)
Profiling system
Aircraft (King Air from University of Wyoming – in picture)

20. QUESTIONS … ???