A tropical cyclone has to stand up straight before it can strengthen, and radar flown through storms by NOAA’s Hurricane Hunter aircraft can show when that is about to happen. A team led by Michael S. Fischer of the University of Miami’s Rosenstiel School examined 1,510 radar analyses from 28 hurricane seasons, 1997 through 2024, and identified four features that separated storms that later lined up vertically from storms that stayed tilted.
The study, titled “To Align or Not to Align? That Is the Question,” appeared in the Journal of Geophysical Research: Atmospheres this summer. The University of Miami dates the paper to August 11, 2026, while at least one science news outlet gives July 17, so it is a recent piece of research rather than a fresh discovery. Coverage was republished on ScienceDaily in mid-September, which is why it is circulating again as hurricane season peaks.
Why a storm has to line up before it strengthens
The central idea is vertical alignment. According to the University of Miami’s account of the work, a storm can be tilted, with its rotating center high in the atmosphere separated from the center near the ocean surface. Fischer put the consequence plainly: “A tropical cyclone has to stand up straight before it can intensify. Strong winds higher in the atmosphere can push the top of a storm’s circulation away from the center near the ocean surface. Until those centers come back together, the storm usually cannot intensify substantially.”
That framing matters for forecasters because it turns a vague question, whether a storm will strengthen, into something a radar can observe: is the storm leaning, and is it about to straighten. The researchers looked at the radar structure of storms roughly a day before alignment occurred and compared the ones that aligned with those that did not.
The four warning signs in the radar data
The team identified four characteristics that favored alignment, as laid out in the ScienceDaily version of the university release. The first is a compact, tightly organized circulation close to the ocean surface. The second is a tilt oriented favorably relative to the direction of the vertical wind shear. The third is stronger rising air and heavier rainfall near the low-level center of the storm. The fourth is the surrounding environment: warm ocean water, abundant moisture, and relatively weak winds in the middle layers of the atmosphere.
Fischer described how the first three signs looked in the data. “The storms that aligned already looked different about a day beforehand,” he said. “They had stronger, more tightly wound circulations near the surface and more widespread, vigorous thunderstorms lifting air near that center.” He added that the thunderstorms may be doing more than signaling organization: “They may also help pull the storm’s leaning circulation upright.”
Neither the university release nor the summaries of it give a percentage for how often storms showing these signs went on to strengthen, and the sources reviewed do not describe the signs as a guarantee. What the study reports is a difference in structure between the storms that aligned and the ones that did not, observable about a day ahead.
Tail Doppler radar aboard the Hurricane Hunters
The data come from the Tropical Cyclone Radar Archive of Doppler Analyses with Recentering, known as TC-RADAR, which collects analyses from radar aboard NOAA Hurricane Hunter aircraft. NOAA’s Atlantic Oceanographic and Meteorological Laboratory says the aircraft Doppler systems measure “precipitation and winds,” with the tail radar capturing “near-vertical cross-sections of precipitation and winds,” and that three-dimensional images are sent directly to the National Hurricane Center.
Two of Fischer’s co-authors work at NOAA. George R. Alvey III and Paul D. Reasor are scientists at the laboratory’s Hurricane Research Division, and Reasor’s research centers on how vertical wind shear affects hurricane structure and intensity, including methods for analyzing airborne radar data. The fourth author is Deelan Jariwala. The work was supported by the National Science Foundation under Award No. 2241605.
What forecasters could do with it
The practical claim is modest and specific. Because the measurements are the kind that reconnaissance flights already collect, including wind strength, storm size, thunderstorm coverage, and the direction of tilt, the findings can also be used to test whether high-resolution hurricane models get the alignment process right, according to the university.
Fischer framed the benefit in terms of time. “Even a modest increase in forecast confidence a day earlier can provide more usable preparation time for communities in a storm’s path,” he said. A SciTechDaily write-up ties the findings to rapid intensification, the fast strengthening that shortens warning times for coastal communities, though the university’s own release speaks more generally of strengthening.
Whether the four signs can be turned into an operational checklist is not answered in the sources. What the paper does establish is a documented pattern across 1,510 radar analyses that lets researchers ask a sharper question of every tilted storm, and that pattern rests on 28 seasons of flights.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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