Sunday, April 21st 2019, 1:00 pm - Hurricane Michael joins an elite group, and pushes 2018 closer to an all-time record
Hurricane Michael, which struck the Florida Panhandle in October last year, has joined an elite group. The massive storm, which claimed 59 lives and caused approximately $25 billion in damages, is now one of only four storms to have made landfall in the United States at Category 5 intensity.
The storm's explosive development caught forecasters off-guard as they watched it surge from Category 1 to Category 4 strength in only 24 hours. When it roared ashore on October 10th, estimates put the storm's top wind speeds only 2 mph shy of Category 5 strength.
Debate quickly emerged about the storm's strength, and scientists at NOAA's National Hurricane Center announced on Friday that post-season analysis of the storm prompted an upgrade.
WHY THE INCREASE IN SPEED?
During the 'off season', scientists at the National Hurricane Center (NHC) routinely do analysis on the past season's storms. In the case of Michael, a study of aircraft data, satellite and radar estimates, and surface pressure readings, among other data points, nudged the estimated top wind speed from 135 knots to 140 knots, almost 260 km/h, and over the threshold to make it a Category 5 storm as it rolled into Florida Panhandle.
These analyses rely on data that is often unavailable in real-time, as observation sites become damaged or otherwise unable to transmit data during the heart of the storm.
The NHC report does caution that this 5-knot increase is within the measurements' uncertainty, and even if Category 5 winds were felt along the coast, it was likely only over a small region. "This change in the estimated wind speed," reads the report, "is of little practical significance in terms of the impacts associated with the storm there."
It's also worth noting that this estimate may change again as research into the storm continues.
IN RARE COMPANY
Practical significance aside, the Category 5 at landfall designation does make Hurricane Michael one of a select group. It's only the fourth storm to be rated Category 5 at landfall on record in the United States, and it's the first since the turn of the century -- the most recent Category 5 landfall prior to this being Hurricane Andrew back in 1992.
This enhanced rating also bumps 2018 up the leaderboard when it comes to major tropical storms. Eleven Category 5 storms were recorded around the globe through the year; that's the second-highest number on record, with 1997 only barely holding onto top spot with its 12 storms.
Post-season analysis may see these statistics rearranged as well; both Super Typhoon Jelawat from the Western Pacific and Hurricane Hector from the Central Pacific were near Category 5 at their most intense.