This practice first became standard at airports starting in the 1950s, but later at other official climate reporting sites, such as Manhattan’s Central Park, where 6-hourly measurements did not become routine until the 1990s.Įarlier in our weather history, the standard practice was to record snowfall amounts less frequently, such as every 12 or 24 hours, or even to take just one measurement of depth on the ground at the end of the storm. NOAA’s cooperative climate observers and thousands of volunteers with the Community Collaborative Rain, Hail and Snow ( CoCoRaHS), a nationwide observer network, are trained in this method. At the end of the snowfall, all of the measurements are added up for the storm total. The snowboard depth measurement is done ideally every 6 hours, but not more frequently, and the snow is cleared after each measurement. Official measurement of snowfall these days uses a flat, usually white, surface called a snowboard (which pre-dates the popular winter sport equipment of the same name). Climate studies carefully select a subset of stations with consistent snow records, or avoid the snowfall variable altogether. In fact, the apparent trend toward bigger snowfalls is at least partially the result of new-and more accurate-ways of measuring snowfall totals. Quite simply, our measuring techniques have changed, and we are not necessarily comparing apples to apples. In this case, climate change is an important factor to explore, since we know that the heaviest precipitation events have intensified in many parts of the world (see related story: Torrents and droughts and twisters - oh my!).īut when we turn to snowstorms in the Northeast, or elsewhere in the U.S., there is an additional factor at work when comparing modern numbers with historical ones. (Photo courtesy Matt Kelsch, UCAR.)Īs a hydrometeorological instructor in UCAR’s COMET program and a weather observer for the National Weather Service, I am keenly interested in weather trends. Matt Kelsch has taken 6-hourly snow readings at the official weather station for Boulder, Colorado many times during more than 25 years of volunteer work as the NOAA/National Weather Service cooperative climate observer for Boulder. Why is that? Could it be climate change? Are other factors involved? An unusual number of snowfalls in those top 10 lists have been within the last 20 years, even in cities that have records going back to the 1800s. Northeast, many media outlets posted the top-10 snow events for major cities. January 28, 2015 | As this week’s blizzard rumbled toward the U.S.

Snowfall totals long island