Watch Out For Hanna

Hurricane Hanna nearing the Texas Coast  (Source: NOAA)

The National Hurricane Center officially upgraded “Hanna” to hurricane status this morning as it approaches the southern Texas coast.  Hanna is noteworthy for being the first hurricane of the 2020 Atlantic hurricane season.  It is also the first hurricane to form anywhere in the Atlantic Ocean Basin since Pablo in late-October 2019.  While only a Category 1 as of this writing, it could reach Category 2 intensity with sustained winds of at least 96 mph given its slow forward movement and a favorable environment for intensification.

Not having a hurricane during the first two months of the Atlantic hurricane season isn’t unusual as June and July are typically among the quietest times in the tropics.  However, this season has already set several benchmarks with the earliest C, E, F, G and H named storms.  Prior to Hurricane Hanna, all of the previous tropical storms were relatively weak and short-lived.  Part of that could be attributed to the influx of Saharan dust that created unfavorable conditions for tropical development.

The 2020 hurricane season was forecasted to be busier than average by scientists at both NOAA and Colorado State University.  A key reason is the anticipated development of La Nina conditions by the fall.  However, that wouldn’t directly contribute to the fast start to the season. What’s been favorable is warmer than average sea surface temperatures across much of the western Atlantic, Gulf of Mexico, and Caribbean Sea. 

Given the fast start to the season, Colorado State upped its seasonal forecast slightly in early July.  NOAA will update its seasonal forecast in early August.  Some comparisons have been made between the fast start to this season and the record-breaking 2005 season.  That’s when an Atlantic record of 28 tropical storms, including 15 hurricanes, developed.  Seven named storms developed in June and July of 2005.  However, unlike 2020, three of those storms became hurricanes, including major hurricanes Dennis and Emily.  By comparison, only one hurricane has developed so far this season.

The 1997 Atlantic hurricane season also had a busy month of July with a total of four tropical storms, including one hurricane (Danny).  However, unlike in 2005, or what experts expect this season, the 1997 season was quiet overall due to a powerful episode of El Nino that developed.  Once Hurricane Danny weakened in late-July, the Atlantic didn’t see another named storm until September 1997.  It’s exceptionally rare for the entire month of August to pass without a single named storm in the Tropical Atlantic.

When Hurricane Hanna makes landfall in Texas this weekend, it will the first July hurricane to do so since Dolly in 2008.  It will also be the first hurricane to make landfall in Texas during any month since Harvey in 2017.