A tropical cyclone has to stand up straight before it can intensify, according to Michael S. Fischer of the University of Miami’s Rosenstiel School, and a study of 1,510 Hurricane Hunter radar analyses identified four signs that a tilted, lopsided storm is likely to line up. The work, published in 2026 in the Journal of Geophysical Research: Atmospheres, drew on data from 28 hurricane seasons, 1997 through 2024.
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Fischer, an assistant professor of atmospheric sciences, led the study with George R. Alvey III of the Cooperative Institute for Marine and Atmospheric Studies and NOAA’s Atlantic Oceanographic and Meteorological Laboratory, student Deelan Jariwala, and NOAA’s Paul D. Reasor.
Tilt, shear and why alignment comes first
The study’s starting point, as laid out in the University of Miami’s account of the research, is vertical alignment: a storm’s rotating centers at different heights must stack on top of each other before it can strengthen much. Tilt is the separation between a cyclone’s circulation centers at lower and middle altitudes. Vertical wind shear, meaning changes in wind speed or direction with height, can push the upper circulation away from the surface center and disrupt organization. The paper, titled “To Align or Not to Align? That Is the Question,” is catalogued under DOI 10.1029/2025JD045986, and the National Science Foundation funded it under award No. 2241605.
Forecasters care because fast strengthening can leave coastal communities and emergency managers little time to respond. Fischer is also a core faculty member of the university’s Frost Institute for Data Science and Computing, and Jariwala earned bachelor’s degrees in meteorology and mathematics from the University of Miami in spring 2026, so an undergraduate sits on the author list of a paper built from 28 seasons of aircraft data.
The four signs that favor alignment
The team searched the TC-RADAR archive, short for Tropical Cyclone Radar Archive of Doppler Analyses with Recentering, a database Fischer and colleagues developed from NOAA aircraft data. According to the ScienceDaily summary of the paper, four features favored a tilted storm aligning. First, a compact, tightly organized circulation close to the ocean surface. Second, a tilt positioned favorably relative to the vertical wind shear. Third, stronger rising air and heavier rainfall near the low-level center. Fourth, an environment of warm ocean water, abundant moisture and relatively weak mid-level winds.
Read as a checklist, the four signs map onto four different physical questions: how tight the circulation is near the sea surface, how the tilt sits against the wind shear, how much rising air and rain surrounds the low-level center, and whether the surrounding ocean and atmosphere will feed the storm. The paper’s argument is that these four conditions describe the storms that did line up, and the contrast with storms that stayed tilted is where the forecasting value sits. None of the four is a guarantee, and the study describes them as features that favor alignment rather than as a countdown to rapid strengthening.
What Hurricane Hunter radar contributes
The raw material comes from instruments flown into storms, and the radar is reached by flying the aircraft back and forth through the eye from different approaches. The raw winds are then combined into a picture along the flight track. NOAA’s hurricane hunter radar explainer describes a Tail Doppler Radar that measures wind inside hurricanes wherever there is rain, producing images scientists use to study storm structure and how storms change. Flight-level winds are typically measured at about 8,000 feet, and the radar also estimates winds near 1,600 feet. TC-RADAR gathers many such analyses into a consistent record, with documentation in its README file. Scientists use such imagery to find where a storm’s strongest winds are and how far they extend from the center, which helps forecasters anticipate impacts from the typically weaker winds at the surface. Wind speed appears as background color in knots, and the page’s own key says to add 15 percent to convert knots to miles per hour.
The finding that carries the most weight for forecasting is about timing. Fischer said the storms that aligned already looked different about a day beforehand, with stronger, tighter near-surface circulations and more widespread, vigorous thunderstorms near the center. Fischer said the results suggest those thunderstorms are more than a simple sign of organization. The authors suggest those thunderstorms may actively help pull a leaning circulation upright, rather than only signaling that strengthening is underway.
That has practical consequences. NOAA reconnaissance aircraft already collect many of these measurements on operational missions, so the same variables can be used to test whether high-resolution hurricane models reproduce the alignment process. Fischer has said even a modest increase in forecast confidence a day earlier can provide more usable preparation time. The same measurements also give modelers something concrete to check: if a high-resolution model cannot reproduce the alignment that the aircraft observed, that is a flaw worth finding. The study does not claim to predict every case, and the 1,510 analyses are a record of past storms, not a forecast tool ready to deploy.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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