Erin Strengthens to a Hurricane; Heavy Rainfall Possible in Puerto Rico and the Virgin Islands, the Upper Midwest, South Texas

Hurricane Erin may bring isolated flash and urban flooding, landslides or mudslides, and possible tropical storm conditions to Puerto Rico and the U.S. Virgin Islands this weekend. Scattered thunderstorms and heavy rainfall may bring areas of flooding this weekend over the Upper Midwest. A tropical disturbance will bring locally heavy rain and mainly urban flash flooding to far southern Texas. 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

FWD RSS Feed