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: El Niño near its end. The ENSO Outlook is currently at 'La Niña Watch', meaning there are some signs that a La Niña might form in the Pacific Ocean later in 2024.

Cook Islands Meteorological Services along with regional climate partners will continue to closely monitor conditions in the tropical Pacific as well as model outlooks for further developments.

Status summary: At the 1-month time scale, Pukapuka experienced Very Wet conditions whilst Nassau, Manihiki and Rakahanga experienced Seriously Wet conditions. Very Dry conditions were observed for Mitiaro and Mauke.
No extremes were observed for the Northern Cooks at the 3, 6 and 12-month timescales.
Very Dry conditions were observed for Palmerston, Aitutaki, Takutea, Atiu and Mitiaro at the 3-month timescale. At the 6-month timescale, Seriously Dry conditions were observed for Atiu. Dry conditions for the rest of the group and the southeastern side of Rarotonga. At the 12-month timescale, Seriously Dry conditions were observed for Palmerston and Dry conditions for Aitutaki and Nga-Pu-Toru.

Outlook summary:

For June, a Very high chance of Very Wet conditions for Suwarrow, Nassau and Pukapuka. A High chance of Very Wet conditions for Manihiki, Rakahanga and Penrhyn.
For the Southern Cook Islands, there is a medium chance of Very Dry conditions for Rarotonga and a medium chance of Very Wet conditions for Palmerston.

For June to August 2024, there’s a Very high chance of Very Wet conditions for Pukapuka. A High chance of Very Wet conditions for the rest of the Northern Cooks.

There is a Medium chance of Very Wet conditions for Palmerston, Manuae, Takutea and Nga-Pu-Toru.

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 be impacted. Note the periods are estimates only. Allow for uncertainty associated with island size, topography, and 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.

Extreme Rainfall Outlooks

Rainfall Outlooks for May 2024, and May to July 2024

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