Hurricane Safety and Preparedness

Barry Leaves Its Mark in the Gulf of Mexico by Cooling Down Water Temperatures

Sea-surface temperatures in the Gulf of Mexico compared to average prior to Barry (July 9) and after Barry (July 15).

Barry's sluggish movement through the Gulf of Mexico has caused a short-lived change to sea-surface temperatures.

Water temperatures near the surface of the Gulf of Mexico were much warmer than average before Barry developed. Barry then cooled those waters down over the course of several days through a process called upwelling.

Strong winds in tropical cyclones churn up seawater along their path, causing cooler water from below to rise and mix with surface water. When a tropical cyclone remains over the same area for several days, as Barry did, the effect is more pronounced.

In some cases, the cooler water, which is common in the wake of tropical storms and hurricanes, can lead to a tropical system weakening.

Data collected by buoys showed Barry's impact on sea-surface temperatures in the Gulf of Mexico.

Before Barry formed, a buoy in the central Gulf of Mexico recorded a water temperature of 87.1 degrees on July 10. The water temperature at that location was a few degrees cooler, 84.7 degrees, as of Tuesday morning.

Gulf surface temperatures are still warm enough to support a tropical storm or hurricane, but there has been a temporary reduction in oceanic heat content for now. Because it's the middle of summer, waters cooled by Barry will warm back up in the weeks ahead.

Upwelling Has Occurred With Other Recent Storms

Upwelling occurs fairly regularly but is most noticeable with strong and slow-moving or meandering tropical cyclones.

Before Hurricane Harvey in 2017, water temperatures in the western Gulf of Mexico were 1.5 to 4 degrees Celsius warmer than average, according to NASA. As Harvey churned in the Gulf and dumped tremendous amounts of rainfall on Texas and Louisiana, waters cooled near the coasts.

Sea-surface temperatures cooled near the Texas coast due to Hurricane Harvey in August 2017.
(NASA)

In 2016, Hurricane Nicole's unusual track also led to noticeably cooler water temperatures along portions of its path.

This map shows sea-surface temperature anomalies as Hurricane Nicole passed through the Atlantic Ocean in October 2016.
(NASA)

Nicole formed south of Bermuda on Oct. 4, 2016, and then meandered in generally the same area for several days. In addition, Nicole rapidly intensified to a Category 4 hurricane and remained a major hurricane as it passed close to Bermuda.

Due to the strong winds and its wandering path, Nicole mainly left colder-than-average water temperatures in its wake, as shown on the map above.