Scientists Chase Snowflakes During the Warmest Winter Ever

Not counting this night’s grounded flight, McMurdie and colleagues have flown on 12 trips since the beginning of January. While that may seem like a lot, it's actually about half of what they expected. There just haven’t been very many storms this year. NOAA officials say the 2019-2020 winter, which officially stretches from December to February, is on track to be one of the warmest ever, although the amount of snowfall has varied by region. The Eastern United States is lining up to have the one of the top 10 least snowy winters in the past 126 years, according to a database maintained by Rutgers University. Bostonians tied for their warmest winter on record with an average temperature of 37.9 degrees Fahrenheit. New York’s Central Park has only measured a total of 4.8 inches of snow this winter, just over a foot below the average to date, and its second least-snowy season since records began in 1868. This year, there have been no winter storm warnings for a number of East Coast cities including New York, Cincinnati, Baltimore, Washington D.C. and Pittsburgh.
“The surprising thing is we have gotten fantastic data, despite that,” McMurtie says. “We still have recorded snowstorms. They are just not frequent as expected and not as widespread. We are still learning about the structure of the storms. By making these cloud measurements, it helps us with our forecasting models, and the hope is to improve our forecasting of snowfall on the ground.”McMurdie says the data she and her colleagues are collecting will also probe scientific mysteries about snowstorms. “One of the main things we are investigating is why some winter storms are very snowy and some are not,” she says. “We are investigating why snow is distributed the way it is. Usually it is organized in banded structures. You would see a swath of clouds from Florida to Maine. But within the clouds, snow is not continuous, it is in these narrow banded regions.”
Even though the P-3 Orion is grounded, the scientific team is banking on another aircraft to collect data tonight, a high-altitude ER-2 from Hunter Army Airfield in Savannah, Georgia. As the team watches on a massive computer monitor, the lone pilot takes off around 1 a.m. and reaches an altitude of 65,000 feet in about 20 minutes. He flies up to Lake Ontario, across to Quebec, and then follows a back-and-forth “mowing the grass” pattern down to Pennsylvania using instruments that scan the tops of storm clouds.The ER-2 aircraft carries six different types of radar, lidar, and microwave instruments, all tuned to different frequencies ideal for gathering snow measurements remotely. In contrast, the P-3 is designed to fly right through the snowstorm to sample snow, ice, humidity and temperature. As they track the plane from the ground station at Wallops, several researchers compare the ER-2 data to satellite imagery to get an idea of what’s happening at the upper level of the storm.
Greg Sova wants to know what’s happening lower down, in the heart of the storm. For the past two months, Sova, a graduate student at the University of North Dakota, has been collecting data from a cloud particle imager, a gold-colored instrument affixed under the wing of the P-3 aircraft. A laser beam flows between twin prongs of the torpedo-shaped imager. The device records images of microscopic snowflakes as they pass through the light beam and cast a shadow on a detector.Sova then sorts the snowflake into recognizable categories. “You can tell by the shape of the snowflake at which temperature and how high in the atmosphere the snow is developing,” says Sova. He’s collected hundreds of snowflake pictures on his laptop. Some look like the traditional six-armed crystal you drew back in nursery school, which is technically known as a dendrite. Others look like spiky sticks with blobs on the ends. These are called capped columns. Still others take the form of symmetrical hexagonal shapes connected by a blob in the middle; these Sova likens to the Imperial TIE fighters from Star Wars.