Hanna was unique because it was the first Atlantic hurricane where NOAA had access to a full arsenal of next-generation satellite data, and the public had access to new forecast products. These innovations will help provide more accurate forecasts and better warnings for tropical systems that threaten the U.S. and its territories as we head through the rest of this hurricane season—and many more seasons down the road.
They are also coming at a fortunate time. The 2020 hurricane season has kicked off with a record number of storms in the Atlantic Basin so far. Just last week, NOAA updated its 2020 Atlantic hurricane outlook, and the forecast continues to predict a very busy season with a range of 19–25 named storms and 7–11 hurricanes.
Keeping Watch over the Tropics
At the very heart of hurricane detection, monitoring, and prediction, is NOAA’s advanced fleet of Earth-observing satellites—both geostationary and polar orbiting—that keeps a constant eye on tropical systems from their birth. Satellites have become so critical for tropical cyclone research and forecasting, it’s hard to imagine what things were like before the beginning of the satellite era of the mid-1960s.
“In the pre-satellite era, the tools available to detect tropical storms and hurricanes were limited to aircraft reconnaissance, surface observations from land stations, ships and buoys, and land-based coastal radars,” explained Mike Brennan, Branch Chief of the Hurricane Specialist Unit at NOAA’s National Hurricane Center. “Forecasts at that time were quite limited in skill.”
More than 50 years later, instruments on NOAA’s Joint Polar Satellite System (JPSS) satellites, NOAA-20 and Suomi-NPP, provide scientists and forecasters a view of the entire globe twice a day. These data and imagery reveal the structure, intensity and cloud temperature of a tropical system, along with other features, such as lightning. The data from JPSS satellites are also the backbone for NOAA’s life-saving forecasts when tropical storms and hurricanes are looming on the horizon.
Hovering 22,300 miles above the equator, NOAA’s Geostationary Operational Environmental Satellites (GOES-16 and GOES-17) monitor a tropical cyclone’s evolution by measuring infrared and visible radiation from the atmosphere and surface in real-time with their Advanced Baseline Imager. These measurements tell us about wind at various levels in the atmosphere, sea surface temperatures, and cloud properties. They also orbit around the Earth at the same speed Earth rotates, which allows GOES satellites to watch a specific area and give forecasters a view of how a tropical system changes over time—another crucial component to understanding and predicting it.
“Satellite data provide critical information about the current location of a tropical storm or hurricane,” Brennan noted. “In particular, high-resolution visible imagery helps the forecaster locate the low-level circulation center, which serves as the starting point for the track forecast. Satellites [also] provide information about sea surface temperatures, ocean heat content, vertical wind shear and atmospheric moisture that can be important to tropical cyclone intensity.”
Something New in Orbit
This year, the U.S. added data from another group of satellites into the mix. The Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC-2) is a new fleet of six small satellites launched in June 2019. Since May 26, 2020, the constellation has begun feeding more than 4,000 vertical sets of measurements of atmospheric temperature and humidity in the tropics and subtropics daily into tropical cyclone forecast models. Measuring the moisture in and around tropical cyclones is important because it is a key ingredient for their development and intensification.
Starting this hurricane season, NOAA is using COSMIC-2 data, combined with environmental information from JPSS satellites, wind data from NOAA’s GOES-16 and GOES-17 satellites, and data from the European Metop spacecraft and Japan’s Himawari-8 satellite in its hurricane forecast models.
Additions in 2020
Along with new satellite data pouring into the hurricane forecast models, the National Hurricane Center (NHC) debuted some new products in 2020—all designed to provide more information to the public and decision makers.
This year, NHC started providing a graphical depiction of storm surge inundation values ahead of a tropical system’s landfall. “Storm surge is the push of ocean water inland associated with a tropical cyclone or other weather system,” Brennan said. “Storm surge historically has killed the largest number of people in the United States from tropical cyclones—about half of all direct fatalities.”
These experimental graphics represent the peak height the water could reach above normally dry ground somewhere within the specified areas for the United States’ Gulf and Atlantic coasts, Puerto Rico, and the U.S. Virgin Islands. Hurricane Hanna was the first hurricane to have these experimental graphics available for the public.
Also new in 2020, updates to NHC’s “forecast cone.” NHC now includes 60-hour forecast information in this product, which previously had forecast information every 12 hours through 48 hours, and forecast information at 72, 96, and 120 hours. The 60-hour forecast data are also used as input for storm surge and wind speed probability products, which allows forecasters, officials, and the public to make informed decisions ahead of a land-falling tropical system.
This 60-hour forecast information includes a forecast of the system’s location intensity, and 34-kt (39 mph) and 50-kt (58 mph) wind radii predictions from NHC, when applicable.
More information on these new NHC products—and others—is available here.
For the latest hurricane and tropical storm updates and forecasts this hurricane season, visit www.nhc.noaa.gov.