GLS-043 - Ver 1.0 (Sep 23)

Confidential & Proprietary | 2023 CBRE Inc.

Weather is how the atmosphere behaves at any given moment. This includes rain, snow, cloud cover, air pressure, temperatures, flooding, lightning and so on. These are all short-term phenomena lasting the span of a few days to even seconds. Climate is a description of the weather over a long period of time in months, years, and decades. The variables used for the climate are simpler, usually just temperature, total precipitation / snowfall and wind. Climate is what you can generally expect in a region on any given day (i.e. south Florida, likely to be warm and humid vs Alaska, likely to be cold), and the weather is what actually occurs (i.e. thunderstorm in Florida today or milder in Alaska with a rainstorm). 

Climate Vs Weather - The Difference? 

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Koppen Climate Types - USA

Sources: https://weatherworksinc.com/news/climate-vs-weather-whats-the-difference

The Köppen climate types attempt to classify each portion of the United States with a specific type of climate based on precipitation, temperature and the time of year certain temperatures / precipitation patterns occur. For example, much of the southeastern United States is classified as humid subtropical, which means that warm, moist air moves in from the tropics during the summer, which makes it the wettest season. Parts of the Southwest are classified as hot desert, which features hot, arid conditions with lots of sun due to subtropical high pressure systems. 

Precipitation Increases

Sea levels have risen over the last century, which will increase the impact of storm surge. Because of warmer waters, wind speeds of stronger storms will increase because of more heat available for hurricanes to strengthen. As temperatures warm the atmosphere can store more water, leading to greater precipitation totals.  In terms of snowstorms, as temperatures increase, then the frequency of snowstorms will likely decrease over the long term.  However, due to more water vapor available to feed into the storms, the worst storms will have a higher snowfall ceiling.

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GLS-043 - Ver 1.0 (Sep 23)

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Confidential & Proprietary | 2023 CBRE Inc.

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Useful Information

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USA Precipitation Change - 15 Year Window   

Global Warming & Impact On Snow   

Snow Trends - Regions  

Sources: Prism Climate Group - Oregon State University, Climate Central - The Case Of Shifting Snow 

The diagrams below show the % achieved of average annual rainfall and compares 2005 to 2020.  Over the last 15 years the western half of the United States has seen a dramatic decrease in precipitation, vast swathes of the South Western USA are experiencing drought conditions (with less than 20% of expected annual rainfall occurring).  Conversely the Eastern States are experiencing above average annual precipitation.  

2005

2020

A warmer climate means less snowfall, as warmer temperatures are likely to make the snow melt to rain before it hits the earth, or melt it quickly when it hits the ground. In the United States, winters are the fastest warming season, the longest cold snaps are becoming shorter, and the number of days with temperatures below 32°F is expected to continue to decline across the country.

More Snowfall?

• Counterintuitively, global warming could actually cause colder regions to experience greater snowfall in the near to medium term.  That’s because warmer air “holds” more moisture—about four percent more per degree (F)—and that additional moisture can fall as snow when temperatures are below freezing

Eastern Cold Snaps

• According to ongoing academic research, warmer surface temperatures and reduced Arctic sea ice may also be leading to changing atmospheric circulation patterns that bring colder events to the eastern United States

One of the clearest trends to emerge in almost all areas is that snow is decreasing in the “shoulder” seasons—fall and spring. Over the last 50 years, snowfall before December 1 decreased in every region of the country.  After March 1, snowfall decreased in all regions except for the Northeast and the East North Central regions. Winter showed a mixed record, with more snow in northern climates, and decreasing snow in the southern regions. 

For a more detailed look at regional snow trends in the USA please see USA Regional Snow Trends.