Atlantic hurricane season still looks unusually active, NOAA warns
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Satellite view of Hurricane Laura making landfall in Louisiana at night on August 27, 2020. (NOAA/NASA Earth Observatory)
The upcoming Atlantic hurricane season is still likely to be unusually active, though not quite as severe as initially predicted, according to a forecast update from the National Oceanic and Atmospheric Administration (NOAA) on Thursday.
Why it matters: If the forecast proves accurate, this would be the seventh straight year of above average activity in the tropical Atlantic.
- The past two hurricane seasons both exhausted the list of 21 storm names, which was unprecedented. The 2020 season was the most active on record.
- It is unlikely that the current hurricane season will equal the extreme activity of the past two seasons, however, NOAA scientists said during a press call.
The big picture: NOAA is forecasting a 60% chance that the upcoming hurricane season will be above average, with a 30% chance of near normal activity and just a 10% chance of below normal tropical cyclone numbers.
- In terms of the number of storms, the agency is predicting a 70% chance of 14 to 20 named storms. Of these, six to 10 would become hurricanes, and of these, three to five would intensify into major hurricanes of Category 3 or greater.
- These numbers are reduced slightly from NOAA's initial hurricane season outlook issued in May. There have already been three named storms in the Atlantic so far this season.
- August and September are typically the most active months in the Atlantic hurricane season.
- A typical Atlantic hurricane season has 14 named storms, seven hurricanes and three major hurricanes, according to the National Hurricane Center.
What they're saying: "It only takes one storm to devastate a community," said Matthew Rosencrans, NOAA's lead seasonal hurricane forecaster.
Context: NOAA is basing its forecast on several factors, including fluctuations in sea surface temperatures in the North Atlantic Ocean Basin and the continued presence of a La Niña event in the tropical Pacific Ocean.
- La Niña is characterized by cooler than average waters near the equator. It can reduce the winds in the middle and upper atmosphere all the way to the Atlantic.
- These weaker winds can encourage hurricane development by reducing wind shear, which can tear nascent storms apart.
- Climate studies show that increasing ocean and air temperatures are leading to wetter, stronger hurricanes, and that rapidly intensifying storms, such as Hurricane Ida last year, are more likely today than just a few decades ago.
- Forecasters also took into account greater-than-expected variability in sea surface temperatures in the tropical Atlantic, compared to the signal pointing to consistently mild waters seen just a few months ago, Rosencrans said.
Of note: The nation's weather and climate agency currently has an acting director of the National Hurricane Center, Jamie Rhome. The previous director was named as the new head of the National Weather Service.
Threat level: The greatest threat to life from tropical storms and hurricanes is inland flooding, as shown by Hurricane Ida, which killed more people in the northern Mid-Atlantic from flash floods than where it made landfall along the Gulf Coast.
