An Alert Classification System for Monitoring and Assessing the ENSO-Cycle. A Briefing for the Committee for Climate Analysis, Monitoring, and Services (CCAMS) Mike Halpert Deputy Director, CPC. 30 October 2007.
An Alert Classification System for Monitoring and Assessing the ENSO-Cycle
A Briefing for the Committee for Climate Analysis,
Monitoring, and Services (CCAMS)
Deputy Director, CPC
30 October 2007
Kousky, V. E. and R. W. Higgins, 2007: An Alert Classifications System for monitoring and assessment of the ENSO cycle, Weather and Forecasting, Vol. 22, No. 2, 353–371.
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.
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 SST departures meet or exceed +/- 0.5°C along with consistent atmospheric features.
EA: El Niño Advisory
LA: La Niña Advisory
EW: El Niño Watch
LW: La Niña Watch
FEA: Final El Niño Advisory
FLA: Final La Niño Advisory
“ X “ implies a greater than 50% chance of El Niño (E), Neutral (N), or La Niña (L)
122 “Forecasts” from June 1997 – July 2007
80 correct forecasts/42 incorrect (66% correct)
Conditions when forecast made:
La Niña Neutral El Nino
% Correct85% 51%74%
Seasonal Timeseries of Areal Coverage of Precip Anom for the US (<30thor >70th %ile)