As the world warms, the overall area of North America covered by snow is decreasing. One reason is that an increasing percentage of winter precipitation is falling as rain instead of snow in many locations. A Climate Central report found that between sea level and 5,000 feet in elevation, a smaller percentage of winter precipitation is falling asMore
Despite the snow that fell over much of the Northeast late this week, the winter has been warmer than normal for much of the country, in line with broader warming trends. After all, just ahead of that storm, temperatures had soared into the 60s as far north as New York City.
The heavy snow even paradoxically fits with what is expected in a warming world, despite declines in seasonal snowfall. This is because a warmer atmosphere evaporates more water from the ground, making it available for heavier precipitation within individual storms. An uncharacteristically large number of snowfall records have been set since 1980.
While another storm will bring snow to northern New England and upstate New York to close the weekend, enough warm air will pull northward with that system to bring rain to southern New England. Combining that rain with the melting snow will raise the risk of flooding.
Warmth has been a recurring feature of the winter. As a whole, the U.S. had its 18th warmest January on record, according to the National Oceanic and Atmospheric Administration. The warmest locations relative to normal were the Northeast, Ohio Valley and Southeast. Several states from Texas to Maine had one of their 10 warmest Januaries on record. Only the Pacific Northwest was cooler than normal as a rapid series of cold Pacific storms kept the region cloudy and wet.
That pattern has persisted through the first few weeks of February. Only the Northwest has been consistently colder than normal since Dec. 1, with several sites in Washington and Oregon having one of their 10 coldest winters on record through mid-February. Conversely, several locations in the Southeast and the Tennessee Valley are having one of their 10 warmest winters on record. Houston, San Antonio, Tampa, and Miami are having their warmest winters on record so far, according to the Southeast Regional Climate Center.
It’s unlikely that truly polar air will invade the Lower 48 for the rest of the month, which marks the end of meteorological winter. That means the odds are high that the places that have been warmer than normal most of this winter will finish that way.
The outlook from NOAA’s Climate Prediction Center shows above-normal temperatures are likely to rule for the week of Feb. 17-23, with the exception of the West Coast, as a series of storms is forecast to keep things cool there. The CPC’s experimental 3-4 week outlook also shows temperatures will likely remain above normal for most of the country through the first few days of March.
This continues the trend of warming winters over the past few decades as the climate warms from increasing greenhouse gases, with the eastern two-thirds of the country warming the most during the winter.
The warmth this winter is not as extreme as it was last year when a strong El Niño ratcheted up the heat. However, the burgeoning La Niña from the last few months also appears to be gone. Neutral conditions are expected into this summer in the equatorial Pacific Ocean, so the effect of the Pacific Ocean on temperatures in the U.S. will likely be muted in the coming months.
Snow lovers should not lose all hope, as it is still too early to write-off any more chances of snowstorms in the eastern U.S. After all, the infamous 1993 Storm of the Century came in March, and it spread snow from Alabama to Maine.