The recent dearth of landfalling hurricanes in the United States
May 31, 2011
One of the story-lines going into the 2011 season is the recent lack of hurricanes making landfall in the United States. Since Hurricane Ike came ashore in the early hours of September 13, 2008 no hurricane has made landfall in the United States. While this was not particularly surprising in the case of the quiet 2009 season, the 2010 season was amazing for having no U.S. landfalls despite hurricanes being plentiful. In this post we shall review the few sets of consecutive seasons that did not feature at least one hurricane making landfall in the United States.
Before we do so, let us define terms. A hurricane is a tropical cyclone with maximum sustained winds of at least 64 knots (74 mph). Landfall is the act of the center of a tropical cyclone intersecting the coast-line. This should be contrasted with strike, the act of a hurricane’s winds affecting a location (Ref: Glossary of NHC Terms). This distinction is critical for storms affecting the east coast as they can be recorded as striking an area, though they did not make landfall.
Finally, before getting into our review, an explanation of the time-frame. The official record of tropical storms and hurricanes in the Atlantic basin is known as HURDAT. In its original form, the dataset began with the 1886 hurricane season. In 2001, the fruits of comprehensive research allowed the dataset to be extended back to 1851. While this record is certainly incomplete for storms that remained at sea, especially short-lived ones, it can reasonably be considered comprehensive for landfalling storms, especially from ~1900 onward. (for a discussion the original dataset, see is A Tropical Cyclone Data Tape For the North Atlantic Basin, 1886-1982: Contents, Limitations, and Uses starting on page 6. For discussion of the analysis that extended the data, see Documentation for 1851-1910 Alterations and Additions to the HURDAT Databases .)
Having our definitions and time-period set, let us peruse Chronological List of All Hurricanes which Affected the Continental United States and search for consecutive seasons that lacked a hurricane making landfall in the United States.
The first such seasons are 1862, 1863, and 1864. These are outside of the period of complete El Niño Seasonal Oscillation. However, on the basis of eastern Pacific sea surface temperature anomalies and an assumption that the historical record is at least half-way complete, it is reasonable to guess that at least either 1862 or 1864, or both, featured El Niño conditions, which tend to supress hurricanes. Indeed, the records used to make the original dataset showed no storms in 1862 and only one in 1864. Barring a “phantom” hurricane striking an unpopulated part of Florida (and being unobserved by ships prior to landfall) we can be certain that no hurricanes made landfall in those two season, nor did any come particularly close. The case of 1863 is a bit more interesting. Prior to the re-analysis project, only one storm was known for this season and he project found seven more. The known storm is in the record as Tropical Storm #6, which is shown making landfall in North Carolina. While the original documentor of this storm described it as a hurricane off-shore, re-analysis found no evidence to support this assertion, so it is in the books as a tropical storm. By considering this storm, we can say that while the 1862-1864 period may have been without hurricane landfalls, in the United States, there was a storm close to doing so in 1863. (See A Reconstruction of Historical Tropical Cyclone Frequency in the Atlantic from Documentary and other Historical Sources : 1851-1880 for commentary and sources on the analyzed storms).
From there, we must proceed forward some 65 years, to the 1930 and 1931 seasons to find consecutive seasons without U.S. hurricane landfalls. While 1930 was an El Niño year, with the accompanying lack of activity overall, it was not entirely quiet as the 1930 Dominican Republic hurricane was one of the deadliest on record. The reanalysis of 1921-1930 did not change the assessment of U.S. landfall as a tropical storm, however. 1931 was a fair bit more active. However, hurricane landfall activity was restricted to Central America. As the two tropical storms making landfall in America were fairly weak, it is fair to say there was nothing close to a hurricane landfall that year.
From there, we must fast-forward all the way to the 1981 and 1982 seasons. The latter was a hole dug in a valley as far as hurricane activity goes. Falling in the middle of a period in the Atlantic Multi-Decadal Oscillation that was unfavorable for tropical cyclones, it covered one of the strongest El Niños on record. The result was an inactive season, so much so that it and 1983 combined would qualify as inactive on the basis of accumulated cyclone energy. 1981, on the other hand, was positively bustling. However, as there were no storms in the Gulf of Mexico and only a weak tropical Storm Dennis coming up from Cuba and an unusually tracked Tropical Storm Bret coming in on the Delmarva peninsula, there were no hurricanes making landfall in the United States that year. The closest storm in 1982 was Tropical Storm Chris which was strengthening as it made landfall (with 60 mph) winds on the Texas side of the TX/LA border. The fast developing Hurricane Alica of 1983 made landfall in Texas to end the streak. Like Andrew, it serves as a reminder for coastal residents that a season can be quite eventful for some coastal residents despite an overall low level of activity in the Atlantic.
From there we proceed to the tail end of the inactive cycle, 1993 and 1994. Those seasons featured a number of close calls. First, Tropical Storm Arlene formed in the Bay of Campeche, but did not find conditions favorable enough to intensify to a hurricane before making landfall in Texas. Later in the season, Hurricane Emily came close to the Outer Banks of North Carolina and inflicted a fair amount of damge there, but sharply curved away before it would have made landfall. In 1994, Tropical Storm Alberto was intensifying but ran out of time before making landfall in Destin, Florida. The extremely wayward Hurricane Gordon made three landfalls in Florida as a tropical storm and briefly threatened the Outer Banks as a hurricane before the third one of those.
The next pair of seasons are 2000 and 2001, the only pair of seasons in this list in which both featured above average levels of activity (15 storms in both seasons). Five tropical storms made landfall during these seasons. Gordon of 2000 was a hurricane in the eastern Gulf of Mexico, but was weakened by entrainment of dry air. Wind shear supressed Helene and it made Florida Gulf coast landfall just under hurricane strength. In 2001 Allison formed just off the Texas coast and due to extremely heavy flooding became the only tropical storm to have its name retired. Barry may very well have been a hurricane when it made landfall, but ultimately the National Hurricane Center did not find enough sufficiently reliable data to justify rating it as as such. Gabrielle formed just off the western peninsular coast of Florida and ran out of time, making landfall just under hurricane strength as well. Assuming that the asessment of Barry is correct, between 1999′s Irene and 2002′s Lili, there were an amazing 21 hurricanes that formed and did not make U.S. landfall as such (if Barry was a hurricane, the number only drops to 18).
Finally, we arrive at the most recent seasons, 2009 and 2010. 2009 was an year and had below average activity. The only storms making landfall in the U.S., Claudette and Ida were both cut down by wind shear in the Gulf of Mexico. Now we are at the curious case of 2010:
Never before in the record books had there been a season with so many hurricanes (12) and yet none making landfall. In fact, every other season that had at least 10 hurricanes had at least two make landfall in the United States. The only tropical storm to make landfall in 2010 was Bonnie, which did so as a weak storm in South Florida. The only hurricane to come particularly close was the season-opening Alex, which made landfall in Northern Mexico. All others made landfall in Central America or curved out to sea. Since Hurricane Ike hit Texas in 2008, 18 hurricanes have formed without making United States landfall. As such, the number of hurricanes without U.S. landfall was unprecedented only in the aritificial confines of a single hurricane season.
So what factors do these seasons have in common. Most, but not all have at least one below average season; a lower number of hurricanes translates into a lower probability of one making landfall. Many had either no storms forming in the Gulf of Mexico or storms that formed too close to land to have a chance to reach hurricane strength. The near universal factor though, was net “troughiness” off the east coast. In lieu of a high pressure ridge steering hurricanes into the coast, a trough of low-pressure off-shore gives the hurricane a route to remain at sea.
While season forecasters tend to have skill anticipating the first factor, the level of activity, leads on the other factors have proven to be elusive thus far. As the 2000-2001 stretch shows, we can have another active season without having any landfalling hurricanes, though it may be a close run thing.
On the flip side, when the runs of hurricanes without U.S. landfalls end, it tends not to do so quietly. Similar to how the 1981-1982 stretch was broken by Alicia, the 1930-1931 run was broken by a category four hurricane coming into Texas. 1993-1994 was followed by a 1995 season that had four hurricane names retired, with one, Opal, making landfall in the states as a major hurricane. Finally, the afforementioned Lili of 2002 broke the 2000-2001 streak and caused over $1 billion worth of damage in the course of doing so.
In the next day or so, I will have a post on another surprising streak. Five complete seasons have gone by without a major hurricane (category three or above) making landfall in the United States.