Of all the weather elements, perhaps none causes forecasters more fits than predicting snow accumulation totals. Trying to forecast snow presents challenges for local TV meteorologists, government forecasters and even the experts here at AccuWeather.
"It has to do with the liquid to snow ratio," AccuWeather Senior Meteorologist Alex Sosnowski explained. Sosnowski has been forecasting for AccuWeather since 1983 and he has seen and predicted all manner of winter weather in his day.
"If you're off by a couple of tenths of an inch of liquid, that can be the difference between a coating of snow and 3 or 4 inches of snow. And that can have major implications for road conditions and travel in general."
And it's not just the science that makes it tricky, Sosnowski said. Psychology plays a factor too. "The other problem is people only hear the higher number in a forecast range for snow accumulations," he continued. "So, if you predict 3 to 6 inches and a place gets 2 ½ inches, people may think that the forecast was a bust. But actually, it was pretty close."
But there's only so much meteorologists can do about public perception. To better understand the science of snowstorms, particularly those that wreak havoc over the northeastern part of the United States, NASA has announced a new initiative aimed at solving some of the enduring mysteries surrounding snowfall.
Scientists are set to embark on the first comprehensive study of East Coast snowstorms in 30 years, which could help improve the quality of forecasts in the years to come.
The multi-year project is called the Investigation of Microphysics and Precipitation for Atlantic Coast-Threating Snowstorms (IMPACTS) and scientists at NASA expect it will have many benefits once the research is complete.
NASA already uses the vantage point of space to monitor what's happening in planet Earth's atmosphere at any given time, and for this project the space agency will deploy two aircraft to chase and "study the inner workings of snowstorms," NASA said in a statement. NASA will complement the air and space effort with a significant ground game, consisting of numerous weather instruments collecting data from the Earth's surface.
AccuWeather Broadcast Meteorologists Brittany Boyer and Geoffrey Cornish recently interviewed Lynn McMurdie, a research associate professor at the University of Washington, who is currently working with NASA studying East Coast storms.
"We focus on snowstorms that we can reach with our aircraft. We will be looking at, not only the storm itself but inside the storm, there are regions of heavier snowfall organized in things called snow bands," McMurdie said on the AccuWeather Network. Snow bands are narrow areas of heavier precipitation falling as snow that move through the atmosphere.
The project is investigating the processes that contribute to snow band formation and how that might be applied to things like improving forecasts.
Researchers know these snow bands occur, but they don't know why snow bands form or the processes that govern how they evolve over a storm's lifetime, McMurdie said.
"We are going to be measuring the snow bands primarily using aircraft. That enables us to reach snowstorms that are in a variety of locations," McMurdie said.
Areas that get a lot of snow tend to be beneath narrow regions within the clouds called snow bands which produce intense snowfall. Other regions of clouds don't snow as hard.
The team had to do a lot of planning because the two aircrafts require many different components. One will be flying very high above the snowstorms and one will be flying inside the snowstorms.
"The high-flying aircraft called the ER-2 will be equipped with remote sensing instrumentation looking down at the snowstorms as we fly patterns over top of them. The remote sensing instruments are like radars and radiometers," McMurdie said.
"Inside the snowstorm itself will be the P-3 which will be flying right in the clouds where the snowflakes are forming, measuring the environment they are forming in and actually the shapes and sizes of crystals themselves," McMurdie said.
The P-3 is outfitted with cloud probes fitted under the wings that will measure the sizes and shapes of snowflakes, as well as the temperature, water vapor, and other elements of the environment in which they form.
Collectively known as microphysics, "these properties are what govern the small interactions of water droplets and ice crystals as they collide, melt or freeze and eventually fall as rain or snow," NASA said in the statement announcing the initiative.
Relating those two together helps researchers understand the processes that make snow bands, which can result in one place picking up twice or three times as much snow as another very nearby location.
"We are hoping to chase as many winter storms as we possibly can. We are OK with going with the weak ones all the way to the big nor'easters, and we can also go in different locations," McMurdie said.
The aircraft is located in Wallops Flight Facility in Wattsville, Virginia, which allows the team the ability to reach storms that are in the Midwest and on the East Coast, as well as just offshore when the storm has already gone past the country.
"We are looking for any winter storms that are in that range, primarily focusing on snow as best as we can. But if it happens to be raining at the surface, the processes that make the rain start as snow a lot ... we will be measuring that, so that will help us answer our science questions," McMurdie said.
This multi-institutional study will gather data during the next three winters with a six- to seven-week operation window. The team will be able to look at enough storms over that time period to get a better understanding of snowstorm structures.
"For the everyday person, the benefits will be in the long term since we will hopefully improve the way our numerical models handle these snowstorms and the snowfall portions of these snowstorms, and they help us improve our measurement from space," McMurdie said.
NASA has many satellites rotating around the Earth that measure precipitation, and this project will also help measure that and the global water cycle.
"We will improve how we [measure precipitation]," McMurdie said, adding that right now precipitation measurement is challenging for scientists. "These results will help us to do that."
Additional reporting by Doug Hicks.