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

Current El Niño-Southern Oscillation (ENSO) status: The ENSO Outlook continues at La Niña WATCH. La Niña WATCH means there is around a 50% chance of La Niña forming later in 2022. This is approximately double the normal likelihood.

Status summary: The Northern Cook Islands are largely in Meteorological Drought at the 12-month, 6-month, 3-month and at the 1-month timescale (Nassau and Suwarrow move out of drought to No Alert at the 1-month timescale). In the Southern Cook Islands, Palmerston and Aitutaki is in Drought Watch and Mangaia is in a Very Wet status at 12-month timescale. At 6-month timescale, Mangaia joins Aitutaki and Palmerston in Drought Watch, while the rest of the Southern Cook Islands including Rarotonga is in a Drought Warning. At 3-month timescale only Rarotonga is in Drought Watch, and at the1-month timescale all Southern Cooks is Very Dry except for Aitutaki and Palmerston with No Alerts.

Outlook summary: For August, All of Cook Islands is very likely to be Dry, there is a High Chance Dry Alert 3 for the Northern Cook Islands. Southern Cook Islands is mix between Dry Alert 1 and Alert 3.

For August to October 2022, follows a pattern similar to August where there is a High Chance Dry Alert 3 for the 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 Dry Alert for Rarotonga, Atiu, Mauke, Mitiaro and Manuae, while there is No Alert for the rest of the Southern Cook Island stations (Aitutaki, Palmerston 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 August 2022, and August to October 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