Is Climate Change Bringing Us Bigger Snowstorms?

Jackson the Weather Dog makes his way through deep
snow in St. Albans, Vermont Saturday after a large 15.7
inch dump of snow. Individual snowstorms are getting 
larger in Vermont an elsewhere in the East.  It's counter-
intuitive, but climate change is likely responsible
for these epic snowstorms. 

Winter snows in the Northeast are becoming more feast or famine.  

It's either big snowstorms, like the one we in northern Vermont Friday or the New England coast blizzard on January 29, or its nothing.

The science seems to be backing this up. Big snow years in the Northeast, including here in Vermont, are becoming more contingent on extremely heavy, often record breaking individual storms rather than the plodding accumulation of small or mid-sized storms that were more common in the past. 

As the Washington Post notes:

"'Extreme snowstorms, even in the face of longer term declines in winter snow, are entirely consistent with the effects of global warming,' Justin Mankin, a professor at Dartmouth College who studies climate change and variability, said in a statement. 'Storms like this are emblematic of the fact that we need to do a better job of managing their risks ow to make us more resilient for the future.'"

In Boston, 15 of the city's largest 30 single day snowfalls have occurred since 2000. In Burlington, Vermont, exactly half of the city's top 20 snowstorms have happened since 2000.  This in a city where records go back to the 1880s. Only six of these top 20 snowstorms hit before 1986.

True to form, the blizzard on January 29 that missed Vermont set a record in Providence, Rhode Island as its largest single day snowfall in the city's history.

Cities such as New York City, Baltimore Newark, Portland, Maine and Bridgeport, Connecticut all had their first or second biggest single day snowstorm in the recent years, between 2013 and 2020. , 

A major reason why the snowstorms have been getting bigger have to do with water temperatures in the Atlantic Ocean and Gulf of Mexico. 

Those water temperatures are a lot warmer than they used to be.  Warmer water can create more evaporation, which provides more moisture to storms than would otherwise be the case.  Obviously a wetter storm can drop more rain and snow.

If all that extra moisture smacks into cold air, like it did during the blizzard on January 29, you squeeze out a lot more snow.

Even the snowstorm we just got probably gave us a little extra snow than we otherwise would have gotten. Moisture from this storm came mostly from the Gulf of Mexico,which is also currently much warmer than historical normals. 

Some scientists also theorize that a warmer Arctic helps the jet stream meander more than it used to.  Larger dips in the jet stream can create larger storms, so that could be a factor. The science isn't settled on this idea, though. 

Here in Vermont, the bigger sized snowstorms have had an impact on seasonal snow totals. At least until the past couple winters, snowfall in Vermont has been increasing.  Winters up through three years ago were consistently snowier than normal.

The extra snow seems to be on hiatus, at least for now. The winter of 2019-20 brought 69.7 inches of snow to Burlington, Vermont. Last winter tallied up just 63.1 inches.  These totals aren't anywhere near record lows, but they certainly fell short of the new average of snowy winters. (For the record, the least amount of snow in a single season for Burlington was 31.8 inches in 1912-13).

 The snowstorm we just received in the past few days was another example of an unusually heavy storm fed by warm ocean waters. While the storm did not set records in Vermont, accumulations of 12 to 18 inches is unusually big.

This installment brought Burlington's snow total much closer to normal for the season, at least temporarily. Before it snowed, Burlington was about 17 inches  behind normal for the date. As of this morning, we were just a little over four inches behind average for the date. 

Now that Friday's storm is over, it's back to the snow drought. Very little snow is expected in Vermont through mid-month, unless there's a really big surprise that forecast models don't see yet. Don't hold your breath for a big storm in the immediate future, though. 

One more thing about the snow patterns.  Since winters have gotten warmer, the snow from these big storms doesn't stay on the ground for long.  The snow cover from the January 29 blizzard in coastal New England is pretty much gone, thanks to warm temperatures and rain that hit them while it was snowing in northern Vermont Thursday and Friday. 

Here in Vermont, only minor thawing is expected this week, so most of the new snow should stay on the ground. Just don't expect much additional snow.