NEW ORLEANS _ The National Hurricane Center will reanalyze 2017's major storms and may even go back to the mean seasons of 2004 and 2005 after hiccups with a wind speed tool were confirmed during the landfall of Category 5 Michael.
It could take two years to figure out the bugs in the airplane-mounted device that measures storms based on the amount of wind-whipped sea foam on the ocean's surface, meaning no review is coming soon.
But experts at this week's National Hurricane Conference in New Orleans said it's important to correct history if necessary so future storms can be more accurately forecast.
Hurricane Andrew wasn't reclassified a Category 5 until 10 years after its 1992 landfall when technology advanced to the point where meteorologists could recreate and reanalyze the atmosphere at the time of the storm.
And last week's upgrade of Hurricane Michael to a 160 mph Category 5 at landfall may see more tweaks once hurricane experts look at the so-called stepped frequency microwave radiometer (SFMR), which contributed to Michael being underestimated by 5 mph.
"We've already started a project to reevaluate the SFMR in really intense storms," said Jack Beven, a senior hurricane specialist at the NHC and lead author of the Hurricane Michael post-mortem report. "We had the exact same problem with it last year."
The 2017 hurricane season saw three Category 4 storms crash into the continental U.S. or Puerto Rico _ Harvey, Irma and Maria. Harvey was the first major hurricane of Category 3 or higher to make landfall in the U.S. since 2005's Hurricane Wilma, which hit southwest Florida as a 120 mph Category 3.
That hurricane drought, followed by a hyperactive season of super storms, highlighted the problems with the radiometer, including turbulence in the strongest cyclones and taking measurements in shallow water.
First introduced in the 1980s, the tool didn't become operational until the mid-2000s. It uses a downward pointing antenna to read the microwave radiation coming off the ocean's surface by looking at its brightness. Basically, the more white it sees from a frothy ocean, the higher the wind speeds.
But it may have problems in shallow waters near shore where breaking waves can create more whitewater. There are also challenges when the plane experiences too much turbulence and the instrument is no longer pointing down.
Michael was a violent, strong storm near landfall, tossing hurricane hunters so hard during one flight that stall alarms sounded and the automatic pilot shut.
"It was a humbling storm," said Maj. Jeremy DeHart, an aerial reconnaissance weather officer with the U.S. Air Force who flew into Michael near landfall. "The pilot said it was the worst turbulence in his 18 years of flying."
Meteorologist Jason Sippel, who flew on a National Oceanic and Atmospheric Administration flight before DeHart's mission, described the bumpy flight another way.
"I had the pleasure of losing my stomach several times," said Sippel, who works in NOAA's Hurricane Research Division. "It was quite a ride. It made me question whether I ever wanted to be on a plane like that again."
DeHart and Sippel spoke at the conference Wednesday during a session on NHC's use of aircraft data in hurricane analysis and forecasting. In real time, the hurricane center is monitoring satellites, radar, buoys, ship reports, dropping measurement tools from airplanes and looking at plane-mounted devices.
In 2018, NOAA hurricane hunters flew 120 missions and dropped nearly 1,700 so-called "dropsondes" into storms. Even with all the information, only a fraction of the storm is being sampled and there is a lot of "meteorological mayhem" that forecasters don't see.
Data retrieved from the SFMR on DeHart's flight helped in the storm review that increased Michael's land-falling wind speed from 155 to 160 mph, but Beven said the biggest tipping point was a closer look at Doppler radar from Eglin Air Force Base.
"Five miles per hour isn't a big change from a meteorological standpoint," Beven said. "But it's a big change about what is going to be said about Michael in the history books."
Michael is only the fourth Category 5 hurricane to hit the continental U.S.; the others are the 1935 Labor Day Hurricane, 1969's Hurricane Camille and Hurricane Andrew in 1992.
