Hurricane Climatology and the Seasonal Forecast for the 2012 Hurricane Season

1. Hurricane Climatology and the Seasonal Forecast for the 2012 Hurricane Season • John Cole and Andrew McKaughan, NOAA/NWS • WFO Newport/Morehead City, NC

2. Outline • Climatology of Tropical Cyclones in Eastern NC • 2012 Atlantic Hurricane Season Outlook

3. Tropical Cyclone Climatology Focusing on Eastern North Carolina

4. Tropical Depressions Storms and Hurricanes Impacting Cape Hatteras in last 160 years: 131 storms 1851-2011 That’s a frequency of every approximately every 0.8 years, or a storm every one to two years! 59% are TS or less 34% are Cat. 1 or 2 7% are Cat. 3 or stronger www.csc.noaa.gov/hurricanes/

7. Estimated return period in years for hurricanes passing within • 50 nautical miles of various locations on the U.S. Coast

9. Estimated return period in years for major hurricanes passing within 50 nautical miles of various locations on the U.S. Coast

10. Irene

11. 2012 Tropical Cyclone Forecast for the Atlantic Hurricane Basin

12. Factors Influencing the 2012 Atlantic Hurricane Season • Multi-decadal Signal • Sea Surface Temperatures (SST) • El Nino Southern Oscillation (ENSO)

14. Comparison of Major Hurricanes During Multi-decadal Periods and Opposite Anomalies

16. Oceanic Niño Index (ONI) • The ONI is based on SST departures from average in the Niño 3.4 region, and is a principal measure for monitoring, assessing, and predicting ENSO. • Defined as the three-month running-mean SST departures in the Niño 3.4 region. Departures are based on a set of improved homogeneous historical SST. • NOAA’s operational definitions of El Niño and La Niña are keyed to the ONI index.

17. NOAA Operational Definitions for El Niño and La Niña El Niño: characterized by a positive ONI greater than or equal to +0.5°C. La Niña: characterized by a negative ONI less than or equal to -0.5°C. By historical standards, to be classified as a full-fledged El Niño or La Niña episode, these thresholds must be exceeded for a period of at least 5 consecutive overlapping 3-month seasons. CPC considers El Niño or La Niña conditions to occur when the monthly Niño3.4 OISST departures meet or exceed +/- 0.5°C along with consistent atmospheric features. These anomalies must also be forecasted to persist for 3 consecutive months.

18. Pacific Niño 3.4 SST Outlook • Nearly all of the dynamical models predict a transition from ENSO-neutral conditions (Niño-3.4 SST anomalies between -0.5°C and +0.5°C) to El Niño during the Northern Hemisphere summer/fall, with El Niño continuing through the remainder of the year. • The average dynamical model forecast is warmer than the statistical models during the second half of 2012/early 2013. Figure provided by the International Research Institute (IRI) for Climate and Society (updated 15 June 2012).

19. Summary • Equatorial sea surface temperatures (SST) are increasingly above average in the eastern Pacific Ocean. • The atmospheric circulation over the tropical Pacific reflects cool-to-neutral ENSO conditions. • Chances increase for El Niño beginning in July- September 2012.* * Note: These statements are updated once a month in association with the ENSO Diagnostics Discussion: http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/enso_advisory

20. Historical El Niño and La Niña Episodes

22. El Nino Season 1958Cat. 4 Hurricane Helene Brushes NC Coast

23. El Nino Season 1992Cat. 5 Hurricane Andrew Makes Landfall in S. Florida

26. Thanks!