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

Lake-Effect Season Begins around November Ends around March

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

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)

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

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)

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

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 15-20 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!

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

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!!

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

LLAP Bands What does LLAP stand for … ???

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)

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

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

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.)

WRF-modeling of Lake Effect Snows

Opportunities? We here at Oswego have done a lot in terms of Lake-Effect Snow studies Ex: Winter of 2010-2011 Lake-Effect Snow EAGER Grant Research with the Doppler-on-Wheels

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)

QUESTIONS … ???