The National Hurricane Center Recorded an 83-Foot Wave Height Associated with Florence. It Could Be An Error, But Maybe Not

Mike Schuler
Total Views: 86
September 13, 2018

Image posted Wednesday by NHC TAFB showing wave height up to 83 feet (25 meters). Credit: NOAA

My eye lit up in amazement Wednesday morning after I scrolled to a tweet by the National Hurricane Center’s Tropical Analysis and Forecast Branch claiming that satellite radar picked up a significant wave height of 83-feet in the northeast quadrant of Hurricane Florence.

My mind was blown, along with the others who shared, retweeted and commented on the post. A wave significant wave height of 83-feet is enormous. That’s 25 meters!

One thing to keep in mind is when measuring wave heights, scientists use significant wave heights, a measurement that takes the average of the highest one-third of waves. Because it is an average, individual waves can always be taller, sometimes a lot taller.

Also, the best and most accurate way to track wave heights is by using buoy data. However, buoys are stationary and mostly near-shore, so they aren’t always in the right place at the right time. To account for this lack of data, forecasters rely on satellites that use altimeter radar to determine wave height. While good, the data can be less reliable due to some factors, such as weather conditions.

We regularly see 16-meter, 17m, even 18m or more waves in places like the Bering Sea and N. Atlantic primarily associated with powerful hurricane-force winter storms. In fact, the tallest wave height ever recorded, according to the World Meteorological Organization, was measured in 2013 by a buoy located somewhere between Iceland and the United Kingdom. The wave came in at monstrous 19-meters – that’s 62 feet, which is tall enough that the thought alone will send shivers down your spine!

So 83-feet when I saw that tweet from the NHC TAFB, I just had to find out the real story on this.

To do so, I reached out to Chris Landsea, Chief of the Tropical Analysis and Forecast Branch at NOAA, who explained a little bit about this mind-boggling wave height reading. According to Chris, the 83-feet wave height was tracked during a satellite pass early Wednesday morning. The team at TAFB initially thought the reading was accurate, even though forecasts were calling for wave heights closer to 50-feet.

But, as it turns out, when storms like Florence are traveling in a straight line, enormous waves can occur by being trapped along with very strong winds moving in the same direction as the storm’s motion. At the same time, when there are bands are extremely heavy rain, radar sometimes misinterprets the rain as waves, producing incorrect data.

Now, whether or not there was an 83-foot wave in the northeast quadrant of Hurricane Florence yesterday morning, I don’t think we’ll ever know for sure. But whether 85 feet or 55 feet, at the end of the day does it really even matter? Those are seas that you do not want to mess with.

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