On Sunday, the U.S. National Hurricane Center (NHC) updated its advisories regarding a developing weather system located off the Pacific coast of Central America.

"Showers and thunderstorms associated with a broad area of low pressure continue offshore of Central America," the NHC said. "Environmental conditions are conducive for further development of this system, and a tropical depression is likely to form during the next day or two while the system moves slowly northward toward the coast of Central America."

The NHC said areas along the Pacific coasts of northwestern Costa Rica, Nicaragua, Honduras and El Salvador should closely monitor the system's development.

Forecasters also warned that, regardless of whether the system officially develops into a tropical depression, heavy rainfall and life-threatening flash flooding are possible across portions of Costa Rica, Nicaragua, El Salvador and Guatemala through early this week.

U.S. weather experts increased the probability of the system developing into a tropical depression to 90% within the next 48 hours.

As of Sunday, the weather system was positioned along the Pacific Coast from northern Costa Rica to Guatemala and was expected to continue moving northwest toward Mexico over the next three days, according to the NHC.

Although the system is not forecast to make direct landfall in Costa Rica, the National Meteorological Institute (IMN) warned that it could still have significant indirect effects by increasing rainfall across the country.

Costa Rican meteorologists expect the most unsettled weather conditions from Monday through Wednesday as the system moves toward Mexico's Pacific coastline.

Residual moisture associated with the weather system could continue generating showers through Thursday, with conditions expected to gradually improve by Friday.

The IMN also warned that the Intertropical Convergence Zone, a low-pressure belt near the equator that helps fuel storm activity, is expected to enhance rainfall as it shifts across Costa Rica from the Pacific Ocean toward the Caribbean Sea.

The IMN forecast the following rainfall totals across the country:

• Central Mountain Range: 50 to 100 millimeters, with the heaviest rainfall expected at higher elevations.

• Pacific Coast, including Guanacaste Province and Puntarenas Province: 50 to 80 millimeters.

• Central Valley, including San José, Alajuela, Heredia and Cartago: 10 to 30 millimeters.

• Caribbean Coast, including Limón: 30 to 60 millimeters, with thunderstorms likely.