Current El Niño-Southern Oscillation (ENSO) status: The ENSO Outlook remains at La Niña ALERT. This means that the El Niño–Southern Oscillation is currently neutral, but the chance of La Niña forming in the coming months is around 70%. This is roughly three times the normal likelihood of an event forming in any year. When La Niña is present the Northern Cook Islands are likely to be drier than normal and the Southern Cook Islands are likely to be wetter than normal.
Status summary: The Northern Cook Islands are in Meteorological Drought for all timescales with the exception of No Alert status at 3-month timescale for Suwwarrow, and at the 1-month timescale for all locations. The Southern Cook Islands have a Drought Watch for Aitutaki, Manuae and Mitiaro at the 3-month timescale, and Rarotonga has a Drought Watch at the 1-month timescale. All other Southern Cook Island locations have No Alert at all timescales.
Outlook summary: For November, the Northern Cook Islands have High Chance Dry Alerts for Penrhyn, Rakahanga and Manihiki. There are Medium Chance Dry Alerts for Pukapuka in the Northern Cook Islands, and Rarotonga in the Southern Cook Islands. Elsewhere, there is Low Chance for Dry or Wet Alerts or No Alerts.
For November 2021 to January 2022, there are High Chance Dry alerts for all Northern Cook Islands (Penrhyn, Rakahanga, Manihiki, Pukapuka, Nassau and Suwarrow). The outlook is for the long term drought to continue in the coming months.There is a Medium to High Chance Wet alert for all Southern Cook Islands (Palmerston, Aitutaki, Manuae, Mitiaro, Atiu, Mauke, Rarotona, Mangaia). See table/maps below for additional information. See status table below for potential impacts.
After the specified period of below or above average rainfall, the following primary agricultural and hydrological variables and secondary socio-economic and health variables may to be impacted. Note the periods are estimates only. Allow for uncertainty associated with island size, topography, geology and soil type. Contact the relevant sector offices for further information on impacts.
The Standardized Precipitation Index (SPI) is used to assess rainfall status from the MSWEP dataset. MSWEP is a global precipitation product that combines rain gauges, satellite and reanalysis data to a 0.1° resolution. Meteorological Drought is defined as drought assessed by rainfall data only. A site is assigned 'No Alert' when rainfall has been near normal for the period(s) in question. The 3-, 6- and 12-month timescales can accurately predict drought, whereas 1-month status is an approximation only. This is because it is difficult to assess drought at this timescale.
Rainfall Outlooks for November, and November 2021 to January 2022
Seasonal outlooks have been produced using the Australian Bureau of Meteorology ACCESS-S model http://www.bom.gov.au/climate/ahead/about/model/access.shtml. The outlook provides an indication of total one and three-month rainfall, not how intense the rain may be in any one event, nor how it may vary within the three months. A station is assigned 'No Alert' when near normal rainfall is favoured or there are equal chances of below normal, normal and above normal rainfall.
Contact the Cook Islands Meteorological Service for further information.
The Director, Cook Islands Meteorological Service
P.O Box 127, Rarotonga, Cook Islands, Phone: 682 20603,