Will the warm water below it broken off from what is known as the Loop Current add enough energy to turn this into a major hurricane — the process known as rapid intensification?
Thanks to technological advances being tested in the upcoming hurricane season, scientists may be able to answer that question with greater certainty, providing Gulf Coast communities with additional advance warning.
The forecasting improvements come not a moment too soon. NOAA is predicting one of the most active hurricane seasons on record, and climate change is helping to add heat to the waters that can supercharge storms.
Part of the process will involve scientists with NOAA's Hurricane Research Division aboard "Miss Piggy," a WP-3D prop plane, flying through the tops of storms to get a much closer look at what's happening inside. Once there, Styrofoam instrument packages called streamsondes, about the size of a jar of tomato sauce, will be launched into the storm itself.
"Like in the movie 'Twister', where they let all these little things fly into the air in a tornado, we will be launching these from the aircraft. It's almost like throwing confetti out into the storm," said Shirley Murillo, acting director of the research division.
'House of cards'
The packages will immediately begin collecting data — temperatures, relative humidity, wind speed, air pressure, and their GPS positions within the storm. The information will then be transmitted back to the plane and computer systems on the ground.
It is likely enough data to allow modelers to create 3-D views of the growing storms that will help them better understand how the eyewall at the center is growing or weakening. Drones will also be launched within the storm and on the water's surface to gather additional information, while traditional dropsonde instrument packages will be dropped from the plane. That's in addition to a variety of radar and sonar instruments on the plane itself.
Combining all of that, scientists will have a three-dimensional understanding of whether a tropical system is gaining strength, including through rapid intensification.
"We've already seen sea surface temperatures in the main development region of the Atlantic are abnormally warmer than previous years," Murillo said. "And water temperatures don't change as quickly as temperatures in the atmosphere, so if this is an indication of what it's going to be like for the rest of the season, that's one ingredient that really drives hurricane formation that's already in place."
The Streamsondes will help forecasters better understand how the internal structure of tropical storms is changing from a tilted set of thunderstorms blown out of alignment by upper atmospheric wind shear to the more vertical storms that represent a mature hurricane, she said.
"It's like watching a house of cards. It's going to fall over, or it's going to weaken, or it's going through some transition where the deck of cards becomes vertically stacked," she said. "That's when the storm is going to intensify, get its act together."
The research division scientists also will be doing a different set of experiments in areas of the eastern Caribbean Sea to better understand which tropical waves are more likely to trigger storm formations.
In that area, researchers will team with local scientists to release more radiosonde balloons, like those used daily at National Weather Service forecast offices, to gather more information about atmospheric conditions over the waves, which often begin their journey off the coast of Africa.
The much warmer temperatures being seen in the Gulf this year may in part be blamed on global warming. And a March study by scientists with the Université de Toulouse in France pointed out that long-lasting eddies of deep warm water broken off from the Loop Current — as much as 250 miles in diameter — allow those global warming-fed temperatures to add more power to tropical storms.
The Loop Current transfers a nearly half-mile deep section of warm water from the Caribbean into the Gulf Stream that runs along the Atlantic Coast. Every year to 18 months, pieces of that loop break off as eddies that move north and west in the Caribbean before finally dissipating.
Predicting storm surge
The technological improvements are also expected to help predict storm surge, which is always a threat along the Gulf Coast, notes Cody Fritz, who has overseen storm surge forecasting at the National Hurricane Center for the past two years.
Improvements in modeling have allowed his staff to judge storm surge potential along most coastal areas as much as three days in advance of landfalls, an increase of 24 hours in lead time, though actual forecasts are still limited to two days in advance of landfall. The new data may be used to produce maps showing potential flooding along coastlines at that three-day timeframe.
Since stronger winds mean higher surge heights, his team also builds potential rapid intensification effects into their forecasts, he said. Fritz said the model is updated annually with information provided by the U.S. Army Corps of Engineers levee database to show changes that have occurred in local levee systems, an important factor in south Louisiana.
The model performs nearly 1,000 simulations within an hour, based on water and atmospheric conditions in and around a tropical system, to determine the risk for coastal areas. His team uses that information to produce storm surge forecasts, watches and warnings, within about 60 to 90 minutes of the simulation start, he said.
They are also working with the National Water Center to better identify when rainfall during a hurricane may increase flooding threats already resulting from storm surge. One area where that is occurring is in western Lake Pontchartrain and Lake Maurepas, where rainfall to the north can increase surge heights affecting LaPlace and other locations.
© 2024 The Advocate, Baton Rouge, La. Distributed by Tribune Content Agency, LLC.
