PREVIOUS WEATHER REPORTS

Winters in the Ice Box of Connecticut have been getting warmer, and this one is no exception. While the mercury did drop at times, data from the GMF weather station through February this year reveals a familiar trend: above-average temperatures and below-average snowfall.

GMF Property Manager and Head Weather Observer Russell Russ said that “the figures tell a pretty good story— or a bad story if you love snow.” Since 1998 annual (especially wintertime) temperatures have increased at the GMF weather station, while snowfall totals have decreased.

These trends have impacted long-cherished winter recreation opportunities in the Northwest Corner in tangible ways, shortening the Nordic and alpine ski season and eliminating ice fishing on certain lakes in especially warm years. Climatic changes have also had profound impacts on the ecology of forests—many of which researchers are just starting to understand.

The weather station and warming winters

The GMF weather station, known as Norfolk 2SW, is a National Weather Service (NWS) Cooperative Weather Observer Station. It is one of 165 stations in Connecticut which the NWS uses to catalog weather records, and has been used to record weather observations every day since January 1, 1932.

Russ is GMF’s lead weather observer, a position he took over from his father, Forest Manager Darrell Russ, in 2003. He has contributed an additional 22 years of weather data to GMF’s and the NWS’ records, building on the over five decades of readings provided by his father.

After Russ compiled data from the 93 complete annual records since 1932, he found that 10 of the 12 warmest winters on record at Norfolk 2SW were logged since the year 2000. 2024 holds the title as the warmest with an average annual temperature of 48.6ºF, 3.6ºF above the 89-year average of 45ºF from 1932-2020. 2023 and 1998 are tied in third place at 48.4F.

While this winter may have felt frigid at times compared to recent years, the data indicates that monthly averages have remained high, ranging from 5.3ºF warmer than normal in November to 0.2ºF above average in January.

No snow, no grow?

Temperatures this winter have at least stayed closer to normal than many recent years, however snowfall has lagged far behind. Only 38.4 inches have accumulated as of March 1, while the weather station normally averages 65.1 inches through February.

Low snow years are becoming increasingly commonplace at GMF, which on average receives nearly 90 inches of snowfall. Last winter totaled only 45.5 inches of snow between October and May, making it the 6^th least snowy winter in Norfolk 2SW’s records, while all similarly low-snow years have occurred in the past several decades. By contrast, only one of the top 15 snowiest years in Russ’ data archive came after the early 1980s – a particularly snowy 1995-1996 season.

Lower snow yields and warmer temperatures mean that a persistent winter snowpack blanketing the forest floor in Northwest Connecticut may be reduced or eliminated entirely, a scenario which could have negative impacts on forest ecosystems. Research within the past two decades has highlighted how the cold season is “functionally important” to the growing season, according to a 2012 study on snowpack decline and its repercussions in a New Hampshire Forest.

Long thought to be a “dormant season,” winter sees the active continuation of nutrient exchange between roots and soils, a process aided by the insulation of a robust snowpack. Kept at or above freezing, nutrients such as nitrate and phosphate circulate within root systems, keeping trees healthy. A thin or absent snowpack combined with cold temperatures, which has occurred extensively this winter, can freeze soils and interrupt this process. Key species of the New England forest, such as sugar maple and yellow birch, are particularly susceptible to deep freeze-thaw cycles like those of December and January this season. According to a more recent study on the impacts of climate change on winter-dependent biomes, a “deep and long-lasting snowpack drives water and nutrient availability at the start of the growing season.”

Another paper on increased winter runoff events emphasizes that “the synchrony of spring nutrient availability and nutrient uptake” – meaning when spring thaw and plant growth occur simultaneously – is important for natural ecosystems. The paper also finds that midwinter thaws “pose an ongoing and increasing risk to water quality in snow-covered regions,” but that further research is required to identify specific dangers.

Impacts from reduced snowpack and warmer temperatures extend beyond plants to which animal species may thrive in our woodlands. In several instances, white-tailed deer have been shown to succeed in landscapes with reduced snowpack, replacing moose as the dominant browsing species in winter. Different herbivores favor different tree species, so a shift in which herbivore is more common can lead to  cascading impacts on forest plant communities, according to the 2024 paper.

Finally, the livelihood and function of a working forest may be altered by diminished snowfall. The 2012 study predicts the maple sap-harvesting season to be shortened by half and the sap yield reduced “by 20% or more” by the end of the century in New England. The paper also anticipates an earlier and prolonged mud season, potentially affecting winter timber harvests which benefit from frozen and snow-covered roads to protect soils from compaction and erosion.

Ice out

Reduced ice cover on lakes and ponds is “a key indicator of changing winter climate globally,” states the 2024 study, and this is consistent with GMF’s water bodies. Russell Russ has tracked ice-in and ice-out dates since 2000, and maintains that lakes and ponds are freezing over about two weeks later than in “the old days,” and melting about two weeks earlier.

Northern lakes normally experience “inverse stratification” during normal ice cover, when colder water rises to near the surface ice and warmer water sinks beneath. Alternatively, when ice is absent from the surface, these lakes often stratify with warmer water layering above cooler water. Reduced ice cover disrupts the normal circulation of nutrients throughout the lake as the seasons change.

The 2024 study notes that these changes may affect phytoplankton, which serve as the base of the aquatic food webs. One report shows that a specific species of phytoplankton, the diatom Discostella stelligera, has become increasingly abundant – even dominant – in northern lakes. Diatoms are an important component of lake food chains, so the drastic shift in species profile may have cascading ramifications for these ecosystems.

The aquatic life of our lakes is dependent on ice cover, just as the flora and fauna populating the forested landscapes of the Northwest Corner rely on snow cover. As these features of the landscape melt away, researchers are realizing that many surprises are in store as the cold winters of memory fade into the past.