Forecast model of U.S. hurricanes 6 months in advance

Hurricanes are a serious social and economic threat to the
United States. Hurricane Katrina is a grim reminder of this fact.
Recent advances allow skillful forecasts of the U.S. hurricane
threat at (or near) the start of the Atlantic hurricane season.
Skillful forecasts of hurricane landfalls at longer lead times
(forecast horizons) for the complete hurricane season would greatly
benefit risk managers and others interested in acting on these
forecasts. Here we show a model that provides a 6-month forecast
horizon for annual hurricane counts along the U.S. coastline during
the June through November hurricane season. Forecast skill exceeds
that of climatology. The long-lead skill is linked to the
persistence of Atlantic sea-surface temperatures and to
teleconnections between North Atlantic sea-level pressures and
precipitation variability over North America and Europe. The model
is developed using Bayesian regression and therefore incorporates
the full set of Atlantic hurricane data extending back to 1851.

[with R.J. Murnane and T.H. Jagger]

Return periods for Hurricane Katrina

Hurricane Katrina is the most destructive natural disaster in U.S. history. The relative infrequency of severe coastal hurricanes implies that empirical probability estimates of the next big one will be unreliable. Here we use an extreme-value model and show that a hurricane of Katrina's intensity or stronger can be expected to occur, on average, once every 21 years somewhere along the Gulf coast and once every 14 years somewhere along the entire coast from Texas to Maine. The model predicts a 100-year return level of 83 m/s (186 mph) during globally warm years and 75 m/s (168 mph) during globally cool years. The magnitude of this difference is consistent with models predicting an increase in hurricane intensity with increasing greenhouse warming.

[with T.H. Jagger & A.A. Tsonis]

Definition: Hurricane Climate

Hurricane climate is the study of hurricanes that includes the role climate factors play in modulating seasonal, annual, and decadal hurricane activity. Hurricane climatology is the statistics (e.g., mean number of hurricanes, maximum estimated intensity, etc.) of past hurricane activity over some reference time period. The role climate factors play in modulating hurricane activity are examined using empirical, statistical, or dynamical models. For hurricanes occurring over the North Atlantic, climate factors include El Niño, the North Atlantic Oscillation (NAO), the Atlantic sea-surface temperature (SST), and the stratospheric Quasi-Biennial Oscillation (QBO). Hurricane climate also includes the role global warming might have on hurricane activity.