It’s been nearly eight years since the last significant tropical system (Ike) impacted the greater Houston region. So understandably, when NOAA’s National Hurricane Center began tracking the tropical wave that became Hurricane Earl, the region became a little jumpy. Was it, after a record-breaking “hurricane drought” in the Gulf of Mexico, our turn again?
In the end, Earl came nowhere near Houston, instead making landfall as a Category 1 hurricane in Belize. Nevertheless we thought it worth discussing the factors that control the path a hurricane takes, so that the next time a system threatens the Gulf of Mexico we’ll all have a little more knowledge, and perhaps be less susceptible to any hype.
First advisory issued for Tropical Storm Earl on August 2nd, 2016 (Courtesy NWS)
The graphic above is a version of the one we’re all familiar with—it shows the location of then Tropical Storm Earl at the time of the advisory, its projected track and intensity, the forecast cone, and any watches or warnings. Arguably, the most important information in this graphic is the track of the storm, because it (obviously) tells us where the storm is headed, and who will be potentially impacted.
What controls where a hurricane goes?
There are two main forces that control where a hurricane goes—the environment, and something called “beta drift”. The environment around a hurricane is the main force behind the direction the storm goes, “steering” it in one direction or another. The primary environmental steering for storms that form in the deep Atlantic tropics—these are the systems that move off Africa and spin into tropical lows—consists of the east-to-west moving trade winds, which drive storms across the Atlantic and toward the Caribbean and the Gulf of Mexico.
Diagram showing typical tracks of North Atlantic hurricanes (courtesy NOAA)
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