Why Do Hurricanes Stall Over Land? The Science, Explained
When a hurricane's steering winds collapse, the storm can sit in place for days, turning a wind event into a flood catastrophe. Here's why it happens.
For more than 100 hours in August 2017, Hurricane Harvey barely moved. It made landfall near Corpus Christi, wobbled back out over the Gulf of Mexico, and parked itself over southeast Texas, dumping more than 60 inches of rain in spots and turning Houston's freeways into rivers. Harvey was not the strongest storm on record. It was one of the slowest, and that is what made it catastrophic.
Meteorologists call it stalling: a tropical cyclone's forward motion collapses to a crawl, sometimes for days, while it keeps spinning in place. It is not the same as a storm weakening. A stalled hurricane can hold its intensity, or even strengthen, while barely advancing, which means the wind, storm surge and rain all linger over the same towns instead of moving through.
What Makes a Hurricane Stall?
Hurricanes do not steer themselves. They are carried by the broader wind currents around them, pushed along by mid-level, large-scale flows called steering winds. When those winds weaken, stall, or shift abruptly near a coastline, the storm loses its forward push and can sit over one spot until a new weather system nudges it along or it exhausts its fuel.
Over land, that fuel runs out fast regardless of speed, because a hurricane's engine is warm ocean water. Once the eye crosses onto dry ground, it loses the moisture and heat that kept it spinning. A storm that has also stalled compounds the problem: it cannot outrun its own rain shield, so the same neighborhoods take rain band after rain band for a day or more.
Is Climate Change Making Hurricanes Stall More Often?
The evidence splits two credentialed NOAA scientists right down the middle. A 2018 study by James Kossin of NOAA's National Centers for Environmental Information found the forward speed of tropical cyclones worldwide had slowed by about 10% between 1949 and 2016, with the slowdown over land even sharper. Kossin linked the trend to human-caused warming weakening the broader circulatory winds that steer storms.
John Lanzante, a scientist at NOAA's Geophysical Fluid Dynamics Laboratory, published a rebuttal in the same journal disputing the finding.
"The fact that data show abrupt changes in speed, and most of the long-term change in tropical cyclone speed happens in the 1950s and 1960s, makes it very unlikely that climate change is a dominant cause. If climate change was a dominant driver, we would expect to see the bulk of the decrease in speed in recent decades, when climate change has accelerated."
John Lanzante, NOAA Geophysical Fluid Dynamics Laboratory
He argues the apparent slowdown may partly reflect how satellites changed the way storms are tracked, not the storms themselves.
Kossin's response, published alongside Lanzante's paper: the abrupt shifts do not fully explain the trend either, and the slowdown that shows up specifically over land, where satellite-era measurement changes matter less, is the more relevant number for people in a storm's path. The slowdown over land is much more relevant to impacts on humans,
Kossin said. Both scientists agree on one point: the case is not closed, and more research is needed.
Why Does a Slow Hurricane Cause More Flooding Than a Fast One?
Rainfall totals track a storm's speed and size more than its wind speed. A fast-moving Category 1 can pass through in an afternoon and drop a few inches; a stalled tropical storm can idle for days and drop feet. Hurricane Florence did both at once in 2018 — it weakened to a Category 1 before landfall, then all but stopped over the Carolinas, dropping record rainfall that outlasted the wind damage by days. Florence's slow crawl became the story the storm is remembered for, more than its peak winds ever were.
Forecasters now flag stall risk almost as urgently as wind speed and storm surge, because the two are not correlated: a weakening tropical storm parked over one county for 48 hours can flood more homes than a strong hurricane that moves through overnight. It is also why the hurricane cone tells you almost nothing about how big or wet a storm will be, and why the storm's category number, built entirely around wind speed, misses the hazard that ends up doing the most damage. A stalled storm does not need to be strong to be dangerous. It just needs to stay.
