27 November 2012

US Hurricane Intensity 1900-2012

The figure above comes courtesy Chris Landsea of the US National Hurricane Center. It shows the annual intensity of US landfalling hurricanes from 1900 to 2012. The figure updates a graph first published in Nature in 2005 ( Figure 2 here in PDF, details described there).

The red bars show the annual data. The grey straight line is the linear trend (no trend) and the black line shows the five-year average. The most recent five years have the lowest landfalling hurricane intensity of any five-year period back to 1900. By contrast 2004 and 2005 saw the most intense seasons of landfalling storms.

The data shown above includes both hurricanes and post-tropical cyclones which made landfall at hurricane strength (i.e., storms like Sandy). In addition to Sandy, there have been 3 other such storms to make landfall, in 1904, 1924 and 1925. The addition of the storms does not make a significant impact on the graph.


  1. Additional details from Chris Landsea about those 3 post-TC landfalls with hurricane-force winds:

    1904 - Storm #2 - Struck SC as a Category 1, became extratropical, went back over the Atlantic, struck mid-Atlantic/New England as hurricane force extratropical.

    1924 - Originally was Storm #5 listed as extratropical from Florida northward. Reanalyzed last year now as Storm #8 to make landfall as tropical storm in Florida, became extratropical, went back over the Atlantic, struck mid-Atlantic/New England as hurricane force extratropical.

    1925 - Originally was Storm #2 which struck Florida as a Category 1 hurricane. Reanalyzed last year now as Storm #4 to make landfall in Florida as a tropical storm, became extratropical, went back over the Atlantic, made landfall in North Carolina as hurricane force extratropical.

  2. Shouldn't there have been some sort of signal of increased hurricane force associated with increased warming by now? Policies are already being planned with the assumption that such events will become more frequent and powerful unless we increase gas prices, or institute a cabon tax, or block the XL pipeline, etc.

    Is 112 years of data enough data to convince those that have decided that Sandy is the canary in the coal mine for the coming of the hurricane apocalypse? I doubt it.

  3. I wonder if a similar chart could be constructed of landfalling hurricane strength storms north of Cape Hatteras, including Canada. The last ten years up here in Nova Scotia have seemed busy and I know a couple of borderline hurricanes have struck Newfoundland in the last few years. The theory would be that Atlantic warming enables tropical storms to retain their power further north. Any chart, I imagine, would have to at least include the last peak AMO period. Not that Canada is historically a stranger to strong storms, the Saxby Gale of 1869 being notable.

    Here's my unofficial list of notable tropical "events" here in NS over the last ten years:

    2003: Juan (borderline cat 2, direct hit on Halifax, lots of damage)
    2006: Beryl (trop storm)
    2007: Noel (powerful post-tropical, November)
    2008: Kyle (cat 1)
    2009: Bill (cat 1 - just nicked the coast)
    2010: Earl (cat 1)

  4. Using the scientific method of counting bullets on a wiki page :), I find this set of numbers interesting:

    List of Canada hurricanes

    Bulleted Events:
    1775-1899 - 10
    1900-1949 - 4
    1950-1994 - 20
    1995-present - 22

    Reporting bias is an obvious issue with this list. I for one, however, would be interested in seeing a Canadian Power Dissipation Index of Hurricane and Post-Tropical Tropical Force storms. This could indicate more Sandy like events along the north-eastern US seaboard. Some of these coast hugging storms will inevitably steer westward.