National Weather Service United States Department of Commerce

Heavy Rainfall and Flooding Concerns in the Southwest; Coastal Low to Impact the East Coast

Deep tropical moisture will lead to widespread showers and thunderstorms capable of producing flash flooding through early next week over the Southwest and Four Corners. A coastal storm is expected to develop off the southeast U.S. coast tonight and is expected to strengthen and bring flooding, dangerous rip currents, gusty winds and heavy rain up much of the East Coast through early next week. Read More >

ENSO Indices

 

ENSO Regions

 

Southern Oscillation Index (SOI)
standardized anomaly of the mean sea level pressure difference between Tahiti and Darwin

  • traditional ENSO index

  • correlates strongly with SST anomaly indices


NOAA Oceanic Niño Index (ONI)
sea surface temperature anomaly index for Niño 3.4 (5°N to 5°S, 170°W to 120°W)

  • onset of El Niño declared when Niño 3.4 anomaly exceeds +0.5°C for 3-month period

  • to be "full-fledged" El Niño (or La Niña), onset conditions must be met for 5 consecutive 3-month periods


Japanese Meteorological Agency ENSO Index (JMA)
sea surface temperature anomaly index for Niño 3 (4°N to 4°S, 150°W to 90°W)

  • less noisy than traditional SOI and more vigorous than NOAA ONI

  • anomalies must exceed 0.5°C for 6 consecutive 5-month periods


Multivariate ENSO Index (MEI)
weighted anomaly average of 6 meteorological variables in the tropical Pacific

  • sea surface temperature

  • sea level pressure

  • surface air temperature

  • components of surface wind

    • zonal component

    • meridional component

  • total cloudiness fraction of the sky