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

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

Tropical Cyclone Climatology Focusing on Eastern North Carolina

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 Tropical Depressions Storms and Hurricanes Impacting Cape Hatteras in last 160 years: 131 storms Tropical Depressions Storms and Hurricanes Impacting Cape Hatteras in last 160 years: 131 storms

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

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

Irene

2012 Tropical Cyclone Forecast for the Atlantic Hurricane Basin

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

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

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.

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.

Pacific Niño 3.4 SST Outlook Figure provided by the International Research Institute (IRI) for Climate and Society (updated 15 June 2012). 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.

Summary * Note: These statements are updated once a month in association with the ENSO Diagnostics Discussion: 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.*

Historical El Niño and La Niña Episodes Highest El Niño ONI Value Lowest La Niña ONI Value JJA 1951 – DJF 1951/52 1.2ASO 1949 – JAS DJF 1952/53 – JFM SON 1950 – JFM MAM 1957 – JJA AMJ 1954 − NDJ 1956/ OND 1958 – FMA AMJ 1964 – DJF 1964/ MJJ 1963 – JFM JJA 1970 – DJF 1971/ AMJ 1965 – MAM AMJ 1973 – JJA JAS 1968 – DJF 1969/70 1.1SON 1974 – MAM AMJ 1972 – FMA ASO 1983 – DJF 1983/ ASO JFM SON 1984 – ASO ASO 1977 – JFM AMJ 1988 – AMJ AMJ 1982 – MJJ ASO 1995 – FMA JAS 1986 – JFM JJA 1998 – FMA AMJ 1991 – MJJ OND 2005 – FMA ASO 1994 – FMA JAS 2007 – MJJ AMJ 1997 – MAM JJA 2010 – MAM AMJ 2002 – JFM ASO 2011 – FMA JJA 2004 – DJF 2004/ ASO 2006 – DJF 2006/ JJA 2009 – MAM

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

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

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