[From NOAA by Rebecca Lindsey] Like many people do at this time of year, the NOAA Climate communications team has spent some time reminiscing about the holidays of our childhoods. Many have wondered whether we could trust our memories of how snowy the holidays were when we were kids compared to now.
Just for fun, they asked the experts at the Rutgers Snow Lab to show us what their data (based on NOAA satellite images) had to say about whether the U.S. snow extent during the week of Christmas has changed at all in the past 50 years. Fortunately, the team was in the holiday spirit, and they made some time to run a little analysis for us.
The map below shows the change in the average number of snow-covered days during the week of Christmas between 1990-2016 and 1966-1989. Places where the ground was snow-covered up to 25% more frequently in recent decades are colored in shades of blue, and places that were snow-covered up to 25% less frequently are colored shades of brown.
According to the Rutgers’ folks, there seems to have been a modest increase in snow extent during the holiday week today compared to the past for the country as a whole, although it clearly varies a lot from place to place. Further, the scientists emphasize, singling out a particular winter week for scrutiny isn’t especially meaningful as an indicator of long-term trends.
When it comes to meaningful indicators of how snow has changed over time, the scientists say, it’s best to stick to monthly or seasonal averages. By those indicators, says David Robinson, who leads the Rutgers snow lab project, the pattern is clear: Northern Hemisphere snow cover is declining significantly at the end of the cold season (spring/early summer).
[NOAA Snow and Ice coverage map from Sunday, 12/22/2019]
To see maps of monthly and weekly snow extent since satellite records began in 1966, please visit the Rutgers Snow Lab website. Daily snow totals, depth, and other snow analysis are also available from NOAA’s National Center for Environmental Information.