Subseasonal forecast

Valid from november 25 to december 22 , 2024

(4 weeks)

General comment:

The dry season will be establishing itself in the North Pacific, Central Pacific and Central Valley during the week of December 24-30. A significant decrease in rainfall is expected in the Pacific as a result of lower humidity content and stronger trade winds. Likewise, the Caribbean will see an increase in rainfall in the first days of December.

Fig. 1. Weekly precipitation forecast by region for the next 4 weeks.

 

1.Forecast from  november 25 to december 1, 2024

This week, the establishment of the dry season is expected in the North Pacific, Central Pacific and Central Valley. However, normal rainfall will occur in the Central Pacific, South Central Valley and South Caribbean (accumulations between 20-70 mm per week in the Caribbean and greater than 100 mm in the Pacific). In the North Pacific, Guatuso-Los Chiles, above-normal rainfall will occur, despite the establishment of the dry season this week (accumulations greater than 60 mm per week).

Probability of extreme: low (around 20%)
Forecast uncertainty: low

2.Forecast from  december 2-8, 2024

This week there will be a decrease in rainfall in the South Caribbean; most of the country will have very little rainfall, except for the Guatuso Zone, which will have more rain than normal, as well as the North Pacific (accumulated between 20-50 mm per week in the Caribbean and 50-90 mm in the Pacific).

Probability of extreme event:  low (around 20%)
Prognosis uncertainty: medium

3. Forecast from  december 9-15, 2024

This week, normal rainfall will continue throughout the Caribbean and the Northern Zone (accumulated between 20-60 mm per week in the Caribbean and more than 120 mm in the Pacific). In the Pacific, the last days of October and the beginning of November will see slightly above-normal rainfall (over 150 mm per week).

 

Probability of extreme event: low (around 30%)
Prognosis uncertainty: medium

4. Forecast from  december 16-22, 2024

Very weak trade winds and the presence of the Intertropical Convergence Zone over the country. The Intertropical Convergence Zone is expected to favor rainy conditions throughout the Pacific and Central Valley.

Probability of extreme event: low (around 20%)
Prognosis uncertainty: high

 

Forecast of extreme events from  november 4-10, 2024

During this period there is a high probability of tropical cyclones developing in the Caribbean Sea, north of Colombia, there is a probability that the Intertropical Convergence Zone will be activated near the Pacific in Costa Rica, generating very rainy conditions throughout the Pacific and Central Valley the week of October 28 to November 4.

Fig. 2. Forecast of extreme events for the next 2 weeks (training areas).

 

 

Forecaster: Daniel Poleo
Maps: Nury Sanabria Valverde
Unidad de aplicaciones climáticas
Departamento de Desarrollo/IMN