Subseasonal forecast

Valid from   May 27-June 2, 2024

(4 weeks)

General comment:

May will be a month where the rainy season will be established in the country. There is a high probability that it will be very rainy in the South Pacific most of the month; On the other hand, the rainy season will be established in the Central Valley from May 6 to 12, in the North Pacific between the 13th and 20th. In the Caribbean and the North Zone, less intense rains than normal will continue.

 

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

 

1.Forecast from may 6-12, 2024

 

In this period it is expected that the rainy season will be established in the Central Valley, the rains will be more intense than normal in the Pacific (the weekly accumulations are expected to exceed 80 mm in the Central and 120 mm in the South Pacific) . The Caribbean and Northern Zone will have very dry conditions this week. Central Valley will have isolated rains and the North Pacific will have rainfall on the Nicoya peninsula.

 

Probability of extreme: low (around 50%)
Forecast uncertainty: low

2. Forecast from may 13-19, 2024

Very weak trade winds and the Intertropical Convergence Zone continues over the country. Normal rainy conditions are expected throughout the Caribbean and Central Valley (accumulated between 50-80 mm weekly) and rainy in the Central and South Pacific. For this week the rainy season will be established in the North Pacific and in the Northern Zone (although in the latter less rain than normal is expected)

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

3. Forecast from may 20-27, 2024

 

The trade winds will continue to be weak and the Intertropical Convergence Zone over the country, normal seasonal rains are also expected in most of the national territory (the normal weekly accumulations range between 80 and 120 mm in the Central and South Pacific, between 30 -50 mm in the Caribbean and Central Valley).

 

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

4. Forecast from may 27 to june 2, 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 10%)
Prognosis uncertainty: high

 

 

Forecast of extreme events from  April  29- May 27, 2024

 

The proximity of the Intertropical Convergence Zone will be favoring extreme precipitation conditions in the South Pacific region during the period from May 6 to 14. The probability of occurrence of said extreme event is greater than 65%. (Normal weekly rainfall accumulations are between 80-120 mm in the South Pacific, so it is likely that these weekly amounts will be exceeded reaching 200 mm or more in 7 days).

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

 

 

Coordinación: Daniel Poleo
Mapas: Nury Sanabria Valverde
Unidad de aplicaciones climáticas
Departamento de Desarrollo/IMN