Ever since Al Gore used hurricane Katrina as a false example of AGW driven severe weather, there has been a drought of major landfalling U.S. Hurricanes, which can only be a good thing. This year I hope Mr. Gore makes some pronouncement to extend his “Gore effect” on hurricanes. Satire and silliness aside, Dr. Roger Pielke Jr. highlights the number of hurricane drought days.
In preparation for an upcoming talk, have updated the figure above to the start of the 2012 hurricane season, which will begin with a record-long stretch of no intense hurricane landfalls still continuing. (In most browsers you can click on the figure for a larger view.) The long stretch with no intense hurricane landfalls has surely shaped expectations, setting the stage for all sorts of animal spirits to be in play. Oh, to be a commodities trader this summer.
More at The US Intense Hurricane Drought
In the meantime, Dr. Ryan Maue has reconstituted his Tropical page.
This page, which was once at Florida State, is now here: http://policlimate.com/tropical/
Bookmark it. The graphs are telling.
Figure: Historical North Atlantic tropical storm and major hurricane frequency since 1970 from the HURDAT best-track dataset. Since 1970, there have been 465 tropical storms including 102 major hurricanes (22%). Since 1995, the ratio is slightly higher (26%) or 64 major hurricanes out of a total of 250 storms. Data File
Figure: Historical North Atlantic tropical storm Accumulated Cyclone Energy (ACE) since 1970 from the HURDAT best-track dataset. It is clear from the ACE metric that the active-era since 1995 in the Atlantic is well described with a marked step increase. This is partially due to a preponderance of long-lived Cape Verde origin major hurricanes that have higher intensity and longer duration which means more ACE. ACE is the convolution or sum of the reported wind speed squared (in knots) over the lifetime of the storm. Data File
Historical Tropical Cyclone Activity Graphics
Figure: Global Hurricane Frequency (all & major) — 12-month running sums. The top time series is the number of global tropical cyclones that reached at least hurricane-force (maximum lifetime wind speed exceeds 64-knots). The bottom time series is the number of global tropical cyclones that reached major hurricane strength (96-knots+). Adapted from Maue (2011) GRL.
Figure: Last 4-decades of Global and Northern Hemisphere Accumulated Cyclone Energy: 24 month running sums. Note that the year indicated represents the value of ACE through the previous 24-months for the Northern Hemisphere (bottom line/gray boxes) and the entire global (top line/blue boxes). The area in between represents the Southern Hemisphere total ACE.
Figure: Last 4-decades of Global Tropical Storm and Hurricane frequency — 12-month running sums. The top time series is the number of TCs that reach at least tropical storm strength (maximum lifetime wind speed exceeds 34-knots). The bottom time series is the number of hurricane strength (64-knots+) TCs.
Global tropical cyclone power dissipation index
Figure: Global and Northern Hemisphere Power Dissipation Index (Emanuel 2005) 1970-2011: 24 month running sums. Note that the year indicated represents the value of PDI through the previous 24-months for the Northern Hemisphere (bottom line/gray boxes) and the entire global (top line/blue boxes). The area in between represents the Southern Hemisphere total PDI. Power dissipation and Accumulated Cyclone Energy are analogous for running-sum time series — correlation > 0.97