All About Lake-Effect Snow - PDF Free Download

All About Lake-Effect Snow Tom Niziol Winter Weather Expert The Weather Channel CoCoRaHs Seminar November 12 th, 2015

Outline Definition of Lake/Ocean Effect Snow (LOES) Favored Locations in North America/World Conceptual Model of LOES Photo by Tom Niziol Lake Effect Snow NWS Buffalo Parking Lot

Outline Morphology / Snow Band Classification Fun Look At What Heavy Snow Looks Like Photo by Tom Niziol We lose most of our observers when it snows

What Does Lake-Effect Snow Look Like??

Lake/Ocean-Effect Snow Occurs when cold air moves over a relatively warm body of water. In most cases, snow develops in post cold frontal conditions typically favoring fair (clear) weather on a synoptic scale.

Lake/Ocean-Effect Snow Fair Weather Or Not?? -2 F A 37 F 18 F B

Lake/Ocean-Effect Snow Fair Weather Or Not?? A B Barney Wiggin, former MIC at NWS Buffalo, said it best when he claimed that the weather often "clears up stormy" to the lee of the Great Lakes during the winter.

Question 1 True or False Does Lake-effect Snow Only Occur In The Great Lakes??? True 12% False 88%

Where in North America Does It Occur

Where in the World Does It Occur

Question 2 True or False There Is Such A Thing As Lake-effect Rain True 93% False 7%

What Is The Lake-Effect Snow Season Graph by Tom Niziol

Seasonality When Does It End??

Question 3 Which Great Lake Develops The Most Ice Cover Superior 36% Michigan 0% Huron 7% Erie 39% Ontario 18%

Ice Cover On the Great Lakes Lake Huron Lake Ontario Lake Michigan Lake Erie

Great Lakes Bathymetry

Seasonal Ice Cover On the Great Lakes January 1-7

Seasonal Ice Cover On the Great Lakes January 15-21

Seasonal Ice Cover On the Great Lakes February 8-14

Seasonal Ice Cover On the Great Lakes March 1-7

Seasonal Ice Cover On the Great Lakes March 15-21

Seasonal Ice Cover On the Great Lakes April 8-14

Seasonal Snowfall For The Great Lakes

Question 3 What is the highest annual snowfall recorded in one winter season in the Great Lakes Region? 960 13% 466 63% 120 23% 74 4%

On What Scale Does LOES Occur? Horizontal scales are Meso-alpha. 12 mi. 120 mi. as defined by Orlanski (1975). Vertical scale Usually confined to < 10,000 ft. Temporal scale Generally on the order of several hours, though multi-day events are not unusual.

Horizontal Scale Meso-alpha (12mi 120mi) Orlanski (1975).

North Wall of Lake Effect Snow Band Moving Across the City of Buffalo, NY Off Lake Erie Photo by Gordon Scherer

Vertical Scale Lake Effect Convection and its Bigger Summertime Convective Cousin Lake Effect Snow Event Modified Parcel Temp / Dewpoint Lake-Induced CAPE ~300J/kg Summertime Convection Non-modified Temp / Dewpoint CAPE > 2000J/kg

Vertical Scale Lake Effect Convection and its Bigger Summertime Convective Cousin This storm produced nearly 70in. of snow over a 3 day period. Lake Effect Snow Event Modifed Parcel Temp / Dewpoint Lake-Induced CAPE ~300J/kg Summertime Convection Non-modified Temp / Dewpoint CAPE > 2000J/kg

Temporal Scale Anywhere From a Few Hours to Several Days

Temporal Scale Anywhere From a Few Hours to Several Days 126 (320cm.) 82 (208cm.) 50 miles

LOES Meso-Alpha Scale Cold Season Convection Three areas of snowcover downwind of Lake Erie mark this 3-part storm Lake Huron Ontario Lake Ontario New York Lake Erie Ohio Pennsylvania

Conceptual Model Lake Snow Formation

Cold Air Crossing Warm Water (Disney World Orlando, FL)

Cold Air Crossing Warm Water (St. Regis Pond Adirondack Park, NY)

Conceptual Model Lake Snow Formation Inversion

Up Close and Personal With LOES NOAA-16 Satellite Image Aircraft Trajectory

The Real Thing Photo by T. Niziol

Development of Local Instability Modification of Lower Atmospheric Thermodynamic Profile -2 F 37 F 14 F A B

Development of Local Instability Modification of Lower Atmospheric Thermodynamic Profile A GRB B APX

Development of Local Instability Inversion Hgt 900mb 800mb Air Temp -18C -12C Dewpoint -20C -13C

Development of Local Instability Net Change Inversion Hgt +100mb Air Temp +6C Dewpoint +7C

Morphology of Snow Bands Attempts to Classify Snow Band Types Horizontal Roll Multiple Banding Single Band Land Breeze Banding Which Factors Are Responsible For So Many Types of Banding? MesoLow Multi-Lake Banding

Morphology of Snow Bands Attempts to Classify Snow Band Types Horizontal Roll Multiple Banding Single Band Land Breeze Banding The shape of the water body Orientation of the water body with respect to wind direction MesoLow Wind speed and shear within the mixed layer Multi-Lake Banding

Morphology of Snow Bands Multiple Bands Horizontal Roll Convection Horizontal Roll Multiple Banding

Morphology of Snow Bands Multiple Band - Horizontal Roll Convection Counter-rotating vortices in the boundary layer. Major axes aligned with the mean boundary layer wind. Significant speed shear and very little directional shear. Wavelength (updraft to updraft) is about three times the height of the Boundary Layer.

Morphology of Snow Bands Multiple Bands Horizontal Roll Convection Prevailing BL Wind Atlantic Ocean

Morphology of Snow Bands Multiple Bands Horizontal Roll Convection Prevailing BL Wind

Multiple Bands Horizontal Rolls Visible Satellite and WSR-88D Composite Reflectivity Prevailing Flow Horizontal roll convection producing multiple bands under prevailing westerly flow across the short fetch of Lake Michigan

Multiple Bands - Sea of Japan MSLP Feb 2, 2005 00z China Japan

Multiple Bands - Sea of Japan Visible Satellite

Multiple Bands - Sea of Japan Radar Saporro

Multiple Bands - Sea of Japan Tokyo

Multiple Bands Gulf of St Lawrence 850mb Height

Multiple Bands Gulf of St Lawrence NASA MODIS Polar Orbiter Satellite NASA MODIS 2/7/13

NASA MODIS 2/7/13 Multiple Bands Gulf of St Lawrence NASA MODIS Polar Orbiter Satellite

Multiple Bands Gulf of St Lawrence NASA MODIS Polar Orbiter Satellite NASA MODIS 2/7/13

Multiple Bands Cape Cod 850mb Jan 14, 1999 12z

Multiple Bands Cape Cod 925mb Jan 14, 1999 12z

Multiple Bands Cape Cod Jan 14, 1999 12z 850mb 925mb

Multiple Bands Cape Cod Jan 14, 1999 12z 850mb 925mb -18C -10C -5C -15C 10,000 ft. 7,500 ft. 4,500 ft. 2,000 ft.

Multiple Bands Cape Cod MSLP Jan 14, 1999 12z

Multiple Bands Cape Cod KBOX Radar Reflectivity

Multiple Bands Cape Cod CHH Sounding 3600ft = 3⁰F 4200ft = 30⁰F Waldstreicher, J.S., 2002: A foot of snow from a 3000-foot cloud: The Ocean-Effect Snowstorm of 14 January 1999. Bull. Amer. Meteor. Soc., 83, 19 22.

Morphology of Snow Bands Single Bands Horizontal Roll Multiple Banding Single Band Land Breeze Banding Single Band MesoLow Multi-Lake Banding

Morphology of Snowbands Single Band Development Single Band Single Band Lake Huron Lake Ontario

Morphology of Snowbands Wide Lake Multiple Rolls Land Breeze Prevailing Wind Cold Warm

Morphology of Snowbands Narrow Lake Single Band Land Breeze Prevailing Wind

Morphology of Snowbands Thermal Convergence - Single Band Development

Morphology of Snowbands Consolidation Into One Band

Single Band Development Visible Satellite Imagery Prevailing Flow Note the Single Cloud Band Extending Along the Long Axis of Lake Ontario

Single Band Development Visible Satellite and WSR-88D 0.5 Mosaic Radar Reflectivity Radar reflectivity exceeds 35dBz east of Lake Ontario

Single Band Development METAR Reports Convergence Zone Pt. Petre NW20G26 kts. Convergence Oswego SW16G32 kts. Surface Reports Over Eastern Lake Ontario Suggest Strong Convergence

Wind Parallel Single Dominant Band

Wind Parallel Single Dominant Band Lake Effect Storm Dalmation 37 inches in 12 hours

January 20, 2008 1200GMT 2100GMT NAM12 Sfc Reflectivity WSR-88D Montague 0.5 Reflectivity

January 20, 2008 2100GMT NAM12 Sfc Reflectivity

January 20, 2008 2100GMT NAM12 Cross-Section (Omega and Vertical Circulation) NAM12 Photo by Tom Niziol

Multiple Horizontal Rolls vs. Large, Well-developed Single Band

Single Band Wind Parallel (Lake Erie Lancaster, NY)

North Wall of Lake Effect Snow Band Moving Across the City of Buffalo, NY Off Lake Erie Photo by Gordon Scherer

Photo by Tom Niziol Snow Depth After 5-Day Single Band Lake Effect Storm, WFO Buffalo

Single Band Development Gulf of Bothnia Parallel to long axis of the body of water

Single Band Development Gulf of Bothnia November 1-2, 2006 MSLP 850mb L L L L H L

Single Band Development Gulf of Bothnia Parallel to long axis of the body of water

Single Band Development Gulf of Bothnia Mosaic Radar Loop

Single Band Development Chesapeake Bay 850mb Height

Single Band Development Chesapeake Bay 850mb Temperature -9C to -12C

Single Band Development Chesapeake Bay Parallel to long axis of the body of water

Morphology of Snowbands Thermal Convergence - Land Breeze Snowbands

Morphology of Snowbands Land Breeze Snowbands Land Breeze Air Temp: -18 C Water Temp: +3 C Cloudband over Lake Erie that has developed under nearly calm synoptic scale wind and significant air-water temperature differences leading to a well-developed local land breeze circulation.

Thermal Convergence

Thermal Convergence Under weak NE synoptic flow, the general shape and orientation of the body of water often dictates the type of snowband that develops. Niziol (1995)

Thermal Convergence January 8, 1981 Temperatures Air ~ -21C Lake water ~ +3C Lake Michigan MesoLow Under Calm Surface Winds and significant land-lake temperature differences. Niziol (1995)

A Spin-off of a Mesolow 2008 NWA Conference - Louisville, KY Sam Lashley National Weather Service Northern Indiana Jon Hitchcock National Weather Service Buffalo, NY

Feb 20, 2008

20 February, 2008 Radar Mosaic

Feb 20, 2008

What Does Lake-Effect Snow Look Like??

North Wall Lake-Effect Snow Band Buffalo NY November 2014

That s A Lot of Snow

Montague Inn Tug Hill East of Lake Ontario

Snow Lovers Paradise

Who s That Knocking At My Door

This Is Gonna Be A Tough Day

OK I Am Outside, Now What!!! Photo by Tom Niziol

Nothing Like A Cozy Evening Next To The Fire