Caribbean Sea: Hurricane Grace tracking westward in the Caribbean Sea Aug. 18 /update 10

Event

Hurricane Grace is tracking westward in the Caribbean Sea, west of the Cayman Islands, Aug. 18. As of 22:00 CDT, the storm's center of circulation was approximately 205 km (125 miles) east-southeast of Tulum, Mexico. Forecast models indicate the system will maintain its strength as it continues to move westward before making landfall as a Category-1 hurricane in Quintana Roo State, Yucatan Peninsula, Mexico, early Aug. 19. After landfall, the storm is forecast to weaken slightly into a tropical storm as it tracks westward over the Yucatan Peninsula and exits into the Gulf of Mexico by late Aug. 19. Grace is then likely to strengthen again into a Category-1 hurricane as it tracks westward in the Gulf of Mexico toward central Mexico through late Aug. 20. The system is subsequently forecast to make another landfall as a Category-1 hurricane over Veracruz State late Aug. 20. The system will then rapidly weaken as it tracks westward across Mexico and will likely transition into a post-tropical cyclone with tropical depression strength winds when it reaches Michoacan State late Aug. 21. Some uncertainty remains in the track and intensity forecast, and significant changes could occur in the coming days.

Government Advisories

As of 22:00 CDT Aug. 18, the following warnings and watches are in effect:

• Hurricane Warning: Yucatan Peninsula, Mexico, from Cancun to Punta Herrero, including Cozumel

• Hurricane Watch: The coast of mainland Mexico, from Puerto Veracruz to Cabo Rojo

• Tropical Storm Warning: Yucatan Peninsula, Mexico, from north of Cancun to Campeche, as well as from south of Punta Herrero to Puerto Costa Maya

• Tropical Storm Watch: The southern coast of Pinar del Rio Province, Cuba, and Isla de la Juventud; the coast of mainland Mexico, north of Cabo Rojo to Puerto de Altamira

Officials could issue new warnings and/or watches in response to the developing system in the coming days.

Hazardous Conditions
The storm will likely bring further heavy rainfall, strong winds, and rough seas to the Yucatan Peninsula and central Mexico through at least Aug. 21. Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, rivers, and urban areas with easily overwhelmed stormwater drainage systems. Sites located downstream of large reservoirs could experience flash flooding after relatively short periods of intense rainfall. Forecast models indicate the system will likely bring 10-20 cm (4-8 inches) of rainfall to portions of northern and central Yucatan Peninsula as well as 13-25 cm (5-10 inches) of rainfall to central and northern Veracruz State, Mexico through Aug. 20. Torrential precipitation could trigger flash floods and mudslides.

Prolonged sea swells and storm surge generated by the system may result in coastal flooding. Persistent onshore flow could make it difficult for the surge to recede and for water levels to decrease in coastal river catchments. Storm surge is forecast to raise water levels by as much as 0.9-1.5 meters (3-5 feet) above normal tide levels for coastal portions of the Yucatan Peninsula through at least early Aug. 19. In addition to the heavy rain, flooding, and storm surge, the storm could produce damaging wind gusts, resulting in power outages due to fallen trees and toppled utility lines.

Transport
Inclement weather associated with the storm could trigger further localized business, transport, and utility disruptions. Floodwaters and debris flows could render some bridges or roadways impassable, impacting overland travel in and around affected areas. Areal flooding in urban locations could also result in severe traffic congestion. Heavy rain and low visibility may trigger flight disruptions at regional airports.

Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after weather conditions have improved. If there is severe damage to infrastructure, repair or reconstruction efforts may exacerbate residual disruptions.

Advice

Activate contingency plans in areas where officials forecast adverse weather conditions. Heed any evacuation orders that may be issued. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the high potential for severe flooding and storm surge. Stockpile water, batteries, and other essentials in advance. Charge battery-powered devices when electricity is available; restrict the use of cellular phones to emergencies only. Power down mobile devices when not in use. Keep important documents and necessary medications in waterproof containers. Observe strict food and water precautions, as municipalities could issue boil-water advisories following flooding events. Take precautions against insect- and waterborne diseases in the coming weeks.

Plan accordingly for protracted commercial, transport, and logistics disruptions in areas in the path of the storm, especially if vital infrastructure is damaged. Seek updated information on road conditions before driving or routing shipments through areas where flooding has occurred. Confirm flights before checking out of hotels or driving to the airport; clearing passenger backlogs may take several days in some locations.

Resources

US National Hurricane Center
National Weather Service
Cuba Instituto de Meteorologia (Spanish)