OK with me: RG

El Nino conditions have been neutral across the Pacific Ocean during the fourth quarter of 2017 but a weak La Niña continues in the Pacific Ocean. Figure 1 illustrates the behavior of the standard Southern Oscillation Index (SOI) of the Australian Bureau of Meteorology (BOM) from January 2017 to January 2018. Sustained positive values of the SOI above +7 typically indicate La Niña while sustained negative values below −7 typically indicate El Niño. Values between about +7 and −7 generally indicate neutral conditions. 

During the current season, SOI increased from 6.9 in September to +9.1 in October and to +11.8 in November, then decreased to -1.4 in December. It increased agan to +8.9 in January 2018. The overall sustained large positive value indicates a weak La Niña is occurring. Australian BOM reports a weak La Niña WATCH at the current stage and from a global point of view. CropWatch will keep on monitoring the condition of La Niña.

Figure 1. Monthly SOI-BOM time series from January 2017 to January 2018

Source: http://www.bom.gov.au/climate/current/soi2.shtml

The sea surface temperature anomalies in December for NINO3, NINO3.4 and NINO4 regions were −0.9°C, −0.7°C, and −0.2°C in sequence, cooler than 1961-1990 average according to BOM (see Figure 2-3.). Both of BOM and NOAA surmise that the overall cooler condition indicates that a weak La Niña event is occurring during the southern summer and that it will probably continue into the following autumn.

Figure 2. Map of NINO Region

Source:https://www.climate.gov/sites/default/files/Fig3_ENSOindices_SST_large.png

Figure 3. Sea surface temperature anomalies (December, 2017)

Source:http://www.bom.gov.au/climate/enso/wrap-up/archive/20180130.ssta_pacific_monthly.png

December 2017 sea surface temperature departure from the 1961-1990 average.