Cook Islands Meteorological Service Early Action Rainfall Watch The Early Action Rainfall Watch provides sector managers with a brief summay of recent rainfall patterns, particularly drought and the rainfall outlook for the coming months.

Current El Niño-Southern Oscillation (ENSO) status: The ENSO Outlook remains at LA NIÑA, with most atmospheric and oceanic indicators persisting at La Niña levels. Latest oceanic observations, along with most model outlooks, suggest this La Niña event is past its peak, with a return to neutral El Niño–Southern Oscillation (ENSO) forecast around the middle of the southern hemisphere autumn. This is consistent with the typical ENSO event life cycle. 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. CIMS office will continue to closely monitor conditions in the tropical Pacific as well as model outlooks as this La Niña event evolves.

Status summary: The Northern Cook Islands are in Meteorological Drought at 12-month timescales, at 6-month and 3-month timesale only Penrhyn is still in Meteorological Drought while Pukapuka, Rakahanga and Manihiki have moved out of Meteorological Drought but will still be in a Drought Watch (Pukapuka moves to No Alert at the 3-month time scale). At 1-month timescale, Penrhyn remains in Meteorological Drought, Rakahanga and Manihiki is in a Drought Warning with Suwarrow being in Drought Watch. Southern Cook Islands, only Palmerston is at Drought Watch for 6-month timescale, whereas there is No Alert or Very Wet status for all sites at 3-, 6- and 12-month timscales.

Outlook summary: For March, there is High Chance Dry Alert for all of Northern Cook Islands, and Low Chance Dry Alert for majority of Southern Cook Islands except for Rarotonga and Mangaia with No Alert.

For March to May 2022, there is High Chance Dry Alert 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. In the Southern Cook Islands, there is a Low Chance to High Chance Wet Alert for all stations(Palmerston, Aitutaki, Manuae, Takutea, Mauke, Mitiaro, Atiu, Rarotonga and Mangaia).

See table/maps below for additional information. See status table below for potential impacts.

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.

Rainfall monitoring for 12-month, 6-month, 3-month and the past month

About Rainfall Monitoring

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 March 2022, and March to May 2022

About Rainfall Outlook

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,

Website: http://www.met.gov.ck Email: mot.weather@cookislands.gov.ck