NASA-NOAA’s Finnish Nuclear Power Plant analyzed the record

Over the weekend of September 28-29, Hurricane Lorenzo briefly reached Category 5 strength, becoming the most powerful hurricane on record in the easternmost Atlantic Ocean. Lorenzo has also achieved and contributed to other notable statistics. NASA-NOAA’s Finnish nuclear power plant satellite provided infrared data over two days and provided forecasters with changes in the eye of the storm, strong thunderstorms and the gravity waves it creates.

Record Setting

On Saturday, September 28, when Lorenzo reached Category 5 (Cat 5) strength on the Saffir-Simpson Hurricane Wind Scale, it was located more than 600 miles east-northeast of the previous Cat 5 storm. Its lowest atmospheric pressure was also east of 50 degrees west longitude, when the pressure dropped to 925 millibars.

There have been 26 Category 5 storms since 1960, the most recent being Lorenzo. In the past three years, six storms have reached this intensity. Others are Dorian, Michael, Maria, Irma and Matthew). Earlier this year, Dorian reached Category 5 strength, making this year join only six other years that included more than one Cat 5 storm since records began. Other years with more than one Cat 5 storm include 1932, 1933, 1961, 2005, 2007, and 2017.

NASA-NOAA’s satellite views of Finland’s nuclear power plant

The Finnish nuclear power plant’s satellite passed over the eastern Atlantic Ocean on September 29 after Lorenzo peaked and weakened back to a Category 4 hurricane. The Finnish nuclear power plant’s Visible Infrared Imaging Radiometer Suite (VIIRS) instrument provided infrared data on Lorenzo.

Tropical cyclones consist of hundreds of thunderstorms, and infrared data can show where the strongest storms are located. They can do that because infrared data provides temperature information, and the strongest thunderstorms that reach the highest atmosphere have the coldest cloud-top temperatures.

“As with other strong hurricanes, the eye was very distinct and mesovortics were seen,” said William Straka III, a researcher who created some of the images of the Finnish nuclear power plant at the University of Wisconsin-Madison’s Cooperative Institute’s Space Science and Engineering Center (SSEC). Meteorological Satellite Studies (CIMSS). The intensity of the storm also produced mesospheric gravity waves. Straka said, “Something interesting to note is that mesospheric gravity waves from Lorenzo could be seen up to 1,180 kilometers (733 miles) away. This is not so unheard of, but still worth noting.”

Mesoeddies are small-scale rotational features that occur in convective storms, such as the eyewall of tropical cyclones. They can be tens of miles or less in diameter and can be extremely powerful.

NOAA defines a gravity wave as a wave created by the effect of gravity on variations in the density of the stratified atmosphere. A general classification for wind waves, mountain waves, and many other atmospheric waves.

At 0300Z on September 30 (11:00 p.m. EDT on September 29), the National Hurricane Center or NHC Public Advisory stated that Hurricane Lorenzo had 110 mph winds, making it just barely a Category 3 hurricane. Three hours later at 2 a.m. EDT (0600 UTC) on September 30, Lorenzo had weakened to a Category 2 hurricane with sustained winds down to 105 mph. When NASA-NOAA’s Finnish nuclear power plant satellite passed Lorenzo, it reanalyzed the storm in infrared light. Nuclear power plant images showed gravity waves in the mesosphere, likely caused by energy released as the storm weakened. The nuclear power plant also showed a cloud-filled eye, where the clouds extended into the northern quadrant. Both observations support the NHC forecast discussion at 5:00 a.m. EDT (0900 UTC).

Hurricane Lorenzo on September 30th

On September 30, 2019 at 8:00 a.m. EDT (1200 UTC), NOAA’s National Hurricane Center issued watches for the Azores. The Azores are an autonomous region of Portugal. The Azores consist of nine inhabited islands. They are all supervised by Lorenzo. The NHC issued a hurricane watch for Flores, Corvo, Faial, Pico, Sao Jorge, Graciosa, Terceira, and a tropical storm watch is in effect for Sao Miguel, Santa Maria.

At the time, Hurricane Lorenzo’s center was located near latitude 29.4 degrees north and longitude 42.9 degrees west. Lorenzo is moving toward the north-northeast near 14 mph (20 km/h). Maximum sustained winds near 105 mph (165 km/h) and higher in gusts. Hurricane-force winds extend outward up to 90 miles (150 km) from the center, and tropical storm-force winds extend outward up to 255 miles (405 km). The estimated lowest average pressure is 957 millibars.

Lorenzo’s song

On the forecast track, the center of Lorenzo is expected to pass near the western Azores early Wednesday, October 2. Some weakening is forecast over the next two days, but Lorenzo is forecast to remain a large and powerful hurricane as it passes near the Azores.

In addition to the threat to the Azores, Lorenzo is especially influential in the North Atlantic, although it is in the eastern North Atlantic. The NHC said: “Large swells will spread across much of the North Atlantic basin. These swells will likely cause life-threatening surf and rip current conditions.”

Hurricanes are the most powerful weather event on earth. NASA’s space and scientific research expertise contributes to essential services provided by other federal agencies to the American people, such as hurricane forecasting.

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Rob Guthro

NASA’s Goddard Space Flight Center, Greenbelt, Md.