NOAA's GOES West satellite captured this image of three tropical cyclones — Hurricanes Fausto and Genevieve and Typhoon Dolphin — swirling simultaneously in the Pacific Ocean. The image was taken on Tuesday, July 27, at 3:30 PM PDT/ 22:30 UTC. None of the three tropical cyclones made landfall in the United States. Fausto contributed to high surf conditions in Hawaii, and Genevieve also brought high surf to southern California. Typhoon Dolphin continued its track west toward Asia. (Image credit: NOAA Satellites)
It may be surprising, but two of the hurricanes that swirled in the Pacific last week began their journeys thousands of miles away off the western coast of Africa.
Both Hurricanes Fausto and Genevieve developed from tropical waves, which are areas of disturbed weather that rolled off a hot, dry African continent near the island nation of Cape Verde. These waves traveled westward across the Atlantic Ocean, crossed Central America and eventually found favorable conditions over the eastern Pacific, where they strengthened into hurricanes.
“For decades we’ve known that most of our Atlantic hurricanes begin off Africa,” said Jason Dunion, a hurricane scientist from the University of Miami who works at NOAA’s Atlantic Oceanographic and Meteorological Laboratory. “As satellites began to advance, our understanding of the long journeys of hurricanes has accelerated. NOAA satellites provide us a way to track tropical waves far from their source and into the eastern North Pacific Ocean.”
Eric Blake, senior hurricane specialist at NOAA’s National Hurricane Center, said information on how and where a storm begins helps improve forecasts. “Anything we do that maintains our situational awareness, like monitoring these disturbances for signs of development, helps us produce better warnings for people.”
NOAA satellites track disturbances over the globe
NOAA satellites help monitor weather systems around the world, allowing scientists to track tropical waves from the Atlantic to the Pacific.
Paul Chang, a scientist with NOAA’s Center for Satellite Applications and Research, said NOAA’s GOES East and GOES West satellites provide near real-time imagery that rapidly updates to show the movement, evolution and path of tropical disturbances.
The GOES East geostationary satellite, also known as GOES-19, keeps watch over most of North America, as well South America, the Caribbean and the Atlantic Ocean to the west coast of Africa. The GOES West satellite, also known as GOES-18, provides geostationary satellite coverage of the Western Hemisphere, including the western United States, the Pacific Ocean, Alaska and Hawaii. NOAA’s JPSS satellites—along with those operated by international partners—provide additional information as they travel in a polar orbit closer to the Earth, capturing every spot on Earth twice a day with instruments that can see through clouds and provide more data on ocean temperatures.
Scientists identify and monitor tropical atmospheric waves by tracking clusters of thunderstorms and clouds carried by strong winds across the tropics. Some of these waves survive the journey across Central America, and once they reach the warm waters of the eastern Pacific Ocean, they can quickly develop into tropical storms and hurricanes if atmospheric conditions are favorable.
“The Pacific has been ripe for this lately,” said Dunion, adding that sea surface temperatures are running 2 degrees Fahrenheit above normal and the moist atmosphere has also fueled the hurricanes.
This year’s El Niño is already contributing to an active eastern Pacific season. It has been typical during past El Niños for there to be fewer hurricanes in the Atlantic, where stronger upper-level winds over the Atlantic tend to increase wind shear, making it harder for storms to form. Conditions are the opposite in the eastern and central Pacific, where there is less wind shear and warmer sea surface temperatures fuel an increase in tropical cyclones. Typhoon Dolphin was the latest tropical cyclone to appear in the Pacific, and unlike Fausto and Genevieve, it emerged from a disturbance in the central Pacific.
“The number of tropical waves produced in the hurricane nursery over Africa stays pretty constant,” Dunion said. “But suboptimal background conditions in the Atlantic such as increased wind shear during El Niño events are likely to affect how many of these atmospheric waves eventually turn into hurricanes.”