Blizzard conditions in rural Iowa [Credit: NWS Des Moines/Mahaska County EMA]
When hazardous winter weather threatens public safety, forecasters at NOAA’s National Weather Service (NWS) now have a new tool to help protect lives and property. This tool, which taps into imagery and data from NOAA’s GOES and JPSS satellites, helps the NWS better identify where two wintertime dangers—blowing snow and freezing sea spray—are occurring.
“Blowing snow can pose a significant threat. It can cause a sudden reduction of surface visibility to near-zero, posing a serious hazard to both ground and air transportation,” said Bill Line, a research scientist with NOAA NESDIS’ Center for Satellite Applications and Research.
“Freezing sea spray can cause ice to accumulate very quickly on marine vessels, causing them to capsize or sink,” Line added. “Before developing this tool, observations of blowing snow and sea spray were mainly limited to sparse webcams, surface observations and human reports.”
That limitation spurred Line to develop and implement new satellite products to better detect and warn of these hazards, and starting Winter 2024-25, this technology is now available to all U.S. NWS Forecast Offices.
Warning of Freezing Sea Spray
Sea spray near Juneau, Alaska, as seen from the VIIRS instrument on NOAA’s JPSS Program satellites on November 20, 2024 [Credit: NOAA]
For Aaron Jacobs, a senior service hydrologist and meteorologist at the NWS Forecast Office in Juneau, Alaska, the addition of this satellite imagery has provided critical new information for the operational marine forecasts he provides.
When forecasting and alerting for the potential of freezing sea spray, Jacobs and his team have traditionally used some rules of thumb, factors such as water temperature, air temperature and wind speed. However, Alaska’s sparsely distributed surface weather observations have made it challenging to pinpoint if—and where—freezing sea spray is happening, until now.
“The new satellite tool gives us the ability to see when and where sea spray is actually occurring and then utilize other satellite and ground based observations to see if the spray could be freezing spray,” Jacobs said. Once they determine where freezing spray is likely, the forecasters at NWS Juneau then send out alerts through social media and other communications means to let mariners know to avoid those areas.
“What’s more, it helps us verify our forecasts and helps us learn what locations are more susceptible to freezing spray, which allows us to better forecast these hazardous conditions in future events.”
Alerting Forecasters to Blowing Snow
Blowing snow in northeastern South Dakota as seen from NOAA’s GOES-16 satellite on January 13, 2024 [Credit: NOAA]
More than 1,700 miles away from Juneau, freezing sea spray is not something that Steve Fleegel and his NWS team in Aberdeen, South Dakota, contend with. Fleegel, the science and operations officer at the NWS office in Aberdeen, is more concerned about another winter-time threat—blowing snow and its impacts on public safety.
“As blowing snow develops and begins to reduce the visibility below a mile—and especially a quarter of a mile—that’s when the hazards really increase,” Fleegel said. “Those conditions make it easier to lose sight of a vehicle in front of you, the road or any other features when travelling.”
Fleegel said that forecasting blowing snow can be challenging due to uncertainties with several criteria, such as the strength of the wind, the intensity of the falling snow, the state of the snow pack on the ground and the predicted temperatures. All these factors can cause blowing snow to vary significantly from one area to another.
At the NWS Office in Bismarck, North Dakota, science and operations officer Chauncy Schultz agreed that forecasting blowing snow can be a challenge, especially during ground blizzards.
“Ground blizzards happen when strong winds kick up snowfall already on the ground. Until a few years ago, it could be difficult to determine the true geographic extent of blowing snow with these events because they’re not well detected by radar, and surface observations and web cams are still relatively limited in scope,” Schultz said.
Blowing snow across North Dakota as seen from NOAA’s GOES-16 satellite on January 18, 2022 [Credit: NOAA]
With the addition of this new tool, the forecasters in both Aberdeen and Bismarck can now more accurately pinpoint where the most serious threats from blowing snow are located.
“We can actually see the locations where blowing snow is occurring thanks to the satellite imagery, which detects the lofted ice crystals associated with blowing snow, and can even see where the blowing snow is moving,” Schultz said. “This allows us to not only determine where blowing snow is occurring, but also how much of it is taking place, and if it’s being transported into other areas on the strong winds.”
Fleegel added, “With satellite data providing the aerial coverage, we combine that information with surface observations from airports, Department of Transportation sensors and webcams to understand the intensity and hazards associated with the blowing snow. This provides us with a fuller picture of a blowing snow event and allows us to better inform our partners and the public.”
This new operational tool led to Bill Line being awarded NOAA’s prestigious David S. Johnson Award in 2024, which recognizes exemplary work from young scientists who are using satellite data to help save lives, protect the economy and benefit society.
Line’s work with operational uses for satellite data continues in 2025 as well. “One of the projects I am currently leading involves the development of a unique twenty-year blowing dust climatology based off of GOES satellite imagery. This information allows us to better understand where blowing dust events most often originate, when they occur seasonally and when they occur during the day.”
Learn more about Bill Line and his work here.