While El Niño was responsible for last year’s unseasonably dry winter across Central America, the phenomenon’s sister, La Niña, promises to force the reverse effect this year.
La Niña has warmed Caribbean waters and cooled the Pacific Ocean, creating the perfect conditions for a wetter-than-average rainy season. The rainfall probability for the entire Pacific coast of the Central American isthmus is much higher than normal this year, according to forecasts.
In Costa Rica, the National Meteorological Institute (IMN) has projected “extremely rainy” conditions from August through October in the Central Valley and the Pacific slope, with higher than average rainfall levels and more rainy days than normal.
In San José, on average, August, September and October bring 846.6 millimeters of rain. This year, the IMN is forecasting that 1,270 millimeters of rain will fall on the Central Valley during the three-month period.
For the country’s southern Pacific coastal region – from the Central Pacific through the Osa Peninsula – the August-October period will drop 4,125 millimeters of rain this year, up to 45 percent above the historic average for the region.
The agency also predicts that eight cyclones will affect Costa Rica during the 2010 rainy season, four of which will likely reach hurricane strength, while two could become fierce Category 4 or 5 storms.
While Costa Rica rarely receives hurricane-force winds from such storms, the rains that these weather systems can bring have often caused serious damage ranging from floods to landslides.
The IMN categorized this year’s La Niña as “moderate” in strength and projected that her effects have an 80 percent chance of lasting until the end of 2011.
“La Niña changes, significantly, the rain forecasts for the entire country,” said Eladio Solano, a meteorologist with the IMN.
The last time La Niña walloped Costa Rica was in 2007, a year that meteorologists consider a particularly rainy year.
“We expect to see days much like we did in 2007,” Solano said.
While the most water-logged days have yet to arrive, the effects of the torrential rains have already made themselves known.
Last weekend, intense rainfall forced 143 people into shelters, damaged or destroyed hundreds of homes and buildings, and possibly killed a 47-year-old mother in Costa Rica.
Rescue crews from the National Emergency Commission (CNE) and the Costa Rican Red Cross searched in Aserrí, a mountain town south of San José, for Damaris Alvarez, a mother of three, who was carried away by swelling torrents last Friday afternoon.
According to the Red Cross, Alvarez was waiting out the downpour in a concrete structure when water from a confluence of the Río Cañas rushed in and swept her into the stream.
Rescuers searched for Alvarez throughout the weekend but found no signs of her remains. Red Cross teams continued the search this week.
In Corredores, in the country’s Southern Zone, 170 homes were flooded by last weekend’s cascades. Two dams that broke on the Río Claro last week forced 22 people from the zone into temporary shelters. The CNE has deployed a team of specialists to repair the dams.
In San Sebastián, a southwest district of San José, the deluges prompted the CNE to move 121 people from their shanty homes along a riverbank into temporary shelters.
The families remained in the shelter throughout the week while government officials analyzed the state of their homes.
According to the CNE, the victims live in shoddily-built houses on the south bank of the Río Maria Aguilar in the LunaParkbarrio, a squatter village in San Sebastián. Some of the homes collapsed completely during the flash floods.
According to an analysis by Julio Madrigal, a geologist for the CNE, the houses that remained standing should not be inhabited because of high risks of landslides and of the houses collapsing.
The Mixed Institute for Social Aid (IMAS) has agreed to provide financial support to the 121 victims in the shelter, if needed. Nelson Mora, an assessor for IMAS, told The Tico Times that the institute is evaluating the situation “family by family to determine the needs of each one.”
Families whose homes are deemed uninhabitable will receive money to rent new homes, clothing, and basic supplies for cooking such as a stove, and pots and pans.
Other houses may be considered repairable, Mora said. In that case, IMAS will provide construction material for repairs. The institute hopes to have developed a plan for each family as early as next week. For now, the CNE and the Costa Rican Red Cross are providing food and supplies to the families inside the shelter in San Sebastián.
Approximately 78 millimeters of rain fell in San José from Friday, Aug. 20 through Sunday, Aug. 22. The northwestern province of Guanacaste received roughly 157 millimeters of precipitation.
The rains have left an indelible mark on some neighborhoods in Costa Rica and they could be a gloomy preview of what the rest of 2010 has in store.
“We are only halfway through the rainy season, with the most intense rains still ahead of us,” said Solano, the meteorologist with IMN.
The CNE claims to be well prepared, buoyed by ¢30 billion ($59.4 million) in investments made within the last year in anticipation of a swollen list of emergencies in the coming months. These funds have been used to prepare 355 shelters and stock 89 warehouses with supplies across the country.
The CNE has identified 45 cantons that are most vulnerable to floods and has shored up the number of emergency personnel in those areas. In total, the CNE relies on 15,000 disaster relief agents in the country including firemen, police officers and Red Cross volunteers.
IMAS is hoping that part of their ¢100 billion (nearly $200 million) budget will be enough to provide relief to storm victims.
“We have all been preparing for this rainy season as best we can for a year now,” Mora said. “We believe we have everything in order. But, obviously, there are always some things that you can never predict.”