GLS-041- Ver 1.0 (Sep 23)

Confidential & Proprietary | 2023 CBRE Inc.

Forecasting snowfall and determining long-term trends of snow climatology are inherently challenging, but the research teams, have produced analysis of snowfall trends across the United States.  In almost all areas of the country, snow is decreasing in the “shoulder” seasons—fall and spring.  Results from 145 locations show that 116 stations (80%) had decreased snowfall before December, and 96 stations (66%) had decreased snowfall after March 1.  Winter showed a mixed record, with more snow in northern climates and decreasing snow in the southern regions.  Total snowfall was also compared from the 1970s to the 2010s and ranked the 20 cities with the biggest percentage gains and losses, using endpoint analysis (see over).

Snow - Regional Trends  

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Central (Illinois, Indiana, Kentucky, Missouri, Ohio, Tennessee, West Virginia) 

• Decreasing snowfall totals in all three seasons, with the fall season showing the greatest decrease
• 32 out of 43 stations recorded lower snow totals. Nashville (-60%) and Knoxville (-52%)
• Nashville experienced annual average snowfall a foot of snow in the 1970s, but less than 5 inches annually on average during the last decade 

East North Central (Iowa, Michigan, Minnesota, Wisconsin)

• Nearly all stations in these Midwestern states saw a long-term snowfall increase during winter
• Lake-effect snowfall has been increasing around Lakes Superior and Michigan, lake ice cover has decreased in recent years due to warmer temperatures and as lakes remain ice-free for longer stretches, supporting more snow
• Marquette, Mich. had some of the biggest gains, with a 45% increase, equating to an average annual increase of 56 inches during the last decade compared to 1970–79

Northeast (Connecticut, Delaware, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont)

• The Northeast is the only region showing increasing amounts of snowfall
• A number of Northeastern cities experienced significant gains in average annual snow totals since the 1970s, including Atlantic City, N.J. (71%), New York City (66%), and Philadelphia (37%)
• Warming ocean waters off the coast are also making  for favorable conditions for larger and more extreme winter storms, particularly along the East Coast

Northwest (Idaho, Oregon, Washington)

• Analyzing 50 years of data shows snow amounts declining at 91% of stations in the Northwest during the fall
• This is a region where accumulated winter snowpack in the mountainous areas is essential to the annual water cycle, as snowmelt supplies freshwater that sustains local watersheds through the drier summer months
• A growing share of the West has endured worsening droughts since the beginning of the 20th century, straining water supplies and increasing the risk for wildfires

South (Arkansas, Kansas, Louisiana, Mississippi, Oklahoma, Texas) and Southeast (Alabama, Florida, Georgia, North Carolina, South Carolina, Virginia)

• Across most of the southern states, the analysis showed declining trends in snow for a region of the country that had fairly low amounts of snow to begin with
• Snowfall in El Paso, Texas, shrank from 5.73 inches in the 1970s to just 2.76 inches annually during the last decade.  Charlotte, N.C., saw a 39% decrease, from 7.25 inches to just 4.42 inches

Southwest (Arizona, Colorado, New Mexico, Utah)

• Analysis showed snow levels decreasing across the Southwest
• Both a lack of precipitation and temperatures that are increasingly too warm, are leading to snow droughts, which have contributed to recent severe water shortages in the Colorado River Basin and the Rio Grande
• Salt Lake City, the host of the 2002 Winter Olympics, had a 42% decline, going from an annual average of 72 inches per year to 42 inches

West (California, Nevada)

• Snowpack at higher elevations in the western U.S. has decreased by 41%, or an area the size of South Carolina, from 1982 to 2016
• As temperatures warm, the amount of precipitation that falls as snow rather than rain is expected to decrease, accelerating snowmelt
• Snowfall is essential for water resources in this region, as one-third of the water used by California’s cities and farmland comes from melted snowpack

West North Central (Montana, Nebraska, North Dakota, South Dakota, Wyoming)

• In the Northern Rockies and Plains, winter snowfall increased, but snowfall decreased in both the fall and spring seasons
• Over the last decade, Mitchell, S.D., experienced a 77% increase in snowfall compared to the 1970s, with 43 inches average annually

Sources: Climate Central - The Case Of Shifting Snow 

GLS-041 - Ver 1.0 (Aug 23)

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Confidential & Proprietary | 2023 CBRE Inc.

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Useful Information

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Top 20 Cities    

Conclusions - Declining Snow & Consequences For Landscaping  

Sources: Climate Central - The Case Of Shifting Snow 

The tables below show the top 20 cities in the USA for annual snowfall decreases and increases from the period 1970 - 2019

• Since 2000, six winter storms have caused at least $1 billion in damage, all of them in January or later
• Decreasing snow can have negative consequences for climate, agricultural output and the economy.  The reflectivity of fresh snow, known as its albedo, is very high, reflecting more than 80% of incoming sunlight back into the atmosphere (by contrast, darker surfaces such as open oceans reflect only about 6% and trees, plants and soil reflect 10 to 30%)
• Snow also has insulation qualities, acting as a blanket for the soil and its organisms and protecting them from variability in the air temperature above the snow’s surface. When soil freezes, it cannot easily absorb new liquid water, leading to more runoff and potential flooding
• Research has also shown that flood sizes increase exponentially as a higher fraction of precipitation falls as rain rather than as snow, suggesting that flood risk during the winter and spring could increase as our climate warms.  The severe flooding that impacted thousands of homes, as well as agriculture and infrastructure across the Southern Plains in 2019 is estimated to have caused $6.2 billion in damages

Changing snowfall patterns will determine snow removal activities need to be more flexible and dynamic to cope with acute weather conditions in those areas most at risk of severe snow events (in particular the north-eastern USA).  In parallel it is important to understand areas of continuing decline.  Contracts and services need to be fit for purpose to implement this degree of flexibility whilst maintaining optimum service levels and adhering to health and safety protocols.

Top 20 Cities Annual Snowfall Decrease

Top 20 Cities Annual Snowfall Increase

Top 20 Cities & Conclusions

• Due to significant fluctuations in precipitation across the country over last 30 years
  • Concentrate historical data collection to last 15 years
  • Clients want budgets that cover the trends
  • Base budgets on seasonal snowfall totals over last 15 years
• Consider promoting 2 models:
  • Per-push model
    • Client has a clearer understanding of the cost per event 
      
    • Encourages efficiency
  • Tiered model
    • Places a cap on the price
    • Avoids excess costs during lighter snowfall seasons
• Ensure weather data is accurate for:
  • Building out pricing criteria 
  • Ensure supplier is providing event updates in a timely fashion
  • Ensure supplier ties invoices back to accurate and credible snowfall reports

CBRE Recommendations - What Does This Mean For My Client?