Earth from Orbit: 2021 Hurricane Season Has Begun
The 2021 hurricane season is officially underway. June 1 marked the beginning of the Atlantic hurricane season; the eastern Pacific season began on May 15. NOAA is predicting an active Atlantic hurricane season this year, while a near- to below-normal season is expected in the eastern Pacific. The peak of the Atlantic hurricane season historically occurs in September. Hurricane season officially extends through November 30.
Satellites have drastically changed how we forecast and monitor hurricanes. NOAA’s geostationary satellites, GOES-16 and GOES-17, and polar-orbiting satellites, NOAA-20 and NOAA/NASA Suomi-NPP, provide remarkable advances in hurricane forecasting as well as new technology to track the storms—their location, movement, and intensity.
Thus far in 2021, two tropical storms have developed in the Eastern Pacific—Andres and Blanca. Andres formed on May 9 as the earliest tropical storm on record in the eastern North Pacific basin. Tropical Storm Blanca formed southwest of Mexico on May 31. Ana, the first tropical storm of the Atlantic hurricane season, developed northeast of Bermuda on May 22.
NOAA’s Climate Prediction Center is predicting another above-normal Atlantic hurricane season for 2021. Forecasters predict a 60% chance of an above-normal season, a 30% chance of a near-normal season, and a 10% chance of a below-normal season. However, experts do not anticipate the historic level of storm activity seen in 2020. For 2021, a likely range of 13 to 20 named storms (winds of 39 mph or higher), of which 6 to 10 could become hurricanes (winds of 74 mph or higher), including 3 to 5 major hurricanes (category 3, 4 or 5; with winds of 111 mph or higher) is expected. NOAA provides these ranges with a 70% confidence.
This year, NOAA updated the statistics used to determine when hurricane seasons are above-, near-, or below-average relative to the latest climate record. Based on this update, an average hurricane season produces 14 named storms, of which 7 become hurricanes, including 3 major hurricanes.
The extremely active 2020 Atlantic hurricane season ended with a record-breaking 30 named storms (top winds of 39 mph or greater) and 12 landfalling storms in the continental United States. The 2020 season included 13 hurricanes (top winds of 74 mph or greater), including six major hurricanes (top winds of 111 mph or greater). This was the most storms on record, surpassing the 28 from 2005, and the second-highest number of hurricanes on record. Throughout the historic 2020 Atlantic hurricane season, NOAA satellites provided vital data to forecasters.
In 2020, GOES-16 (GOES East) and GOES-17 (GOES-West) wind data were fed into NOAA’s Hurricane Weather Research and Forecasting (HWRF) computer model for the first time. The HWRF is used to forecast the track and intensity of tropical cyclones. Also new to the forecast model in 2020 were data from the COSMIC-2, NOAA-20, and Suomi-NPP satellites. An evaluation of adding these new data sets to the HWRF model showed significant improvements in both track and intensity forecasts.
The JPSS polar-orbiting satellites (Suomi-NPP and NOAA-20) capture data over each spot on Earth twice a day. They measure the state of the atmosphere by taking precise measurements of sea surface temperatures and atmospheric temperature and moisture, which are critical to securing storm forecasts several days in advance. JPSS instruments provide data that is particularly useful in helping forecasters predict a hurricane’s path 3-7 days out.
NOAA-20 and Suomi-NPP also carry a microwave sounder that penetrates clouds, allowing forecasters to see the internal structure of tropical cyclones. This helps forecasters understand the direction, movement and intensity of these storms. The Day-Night Band on JPSS satellites provides a snapshot of a hurricane’s cloud structure at night, along with lightning and gravity waves at various altitudes. Emergency responders also use the Day-Night Band to monitor power outages.
GOES-16 and GOES-17 continuously view the entire Atlantic and eastern/central Pacific hurricane basins to provide real-time tracking and monitoring of tropical cyclones as well as the environmental conditions that cause them to form.
By imaging a storm as often as every 30 seconds, these satellites help forecasters more easily discern the movement of cloud features and provide greater confidence in estimating the center of the storm. The added confidence in locating the center of circulation also helps guide reconnaissance aircraft (“hurricane hunters”) to the correct location.
GOES-16 and GOES- 17 also provide a detailed look at the storm properties of a hurricane, including cloud top cooling, central pressure, and convective structures as well as specific features of a hurricane’s eye, wind estimates, and lightning activity. This information is critical to estimating a storm’s intensity.
Together, NOAA’s geostationary and polar-orbiting satellites make a powerful team. Each provides critical information for hurricane forecasting, tracking, and intensity estimation. Different vantage points, imaging frequency, and instrumentation provide complementary measurements to help forecasters better understand and predict the behavior of hurricanes, improving public safety and protecting life and property.
As hurricane season gets underway, NOAA satellites are keeping vigilant watch. Stay tuned to the National Hurricane Center for the latest information on tropical storm and hurricane activity.
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