Delta (2020)

A tropical depression formed from a tropical wave about 90 nautical miles south of Kingston, Jamaica, at 1800 UTC on 4 October 2020. The system became Tropical Storm Delta on 5 October and moved west-northwest across the western Caribbean. Delta underwent very rapid strengthening and became a major hurricane on 6 October, reaching an initial peak over the northwestern Caribbean. It weakened while crossing the Yucatán Peninsula, regained strength over the Gulf of Mexico, and moved north to make U.S. landfall before quickly weakening and becoming extratropical by 9–10 October.

Delta made two official landfalls. The first was near Puerto Morelos on the northeastern Yucatán Peninsula around 1030 UTC on 7 October as a Category 2 hurricane with sustained winds near 90 kt (about 103 mph). The second U.S. landfall was near Creole, Louisiana, at about 2300 UTC on 9 October as a Category 2 hurricane with maximum winds near 85 kt (about 98 mph).

The storm’s maximum measured intensity was 120 kt (about 138 mph) with a minimum central pressure of 953 mb on 6 October, when Delta was a Category 4 hurricane over the northwestern Caribbean. A second peak intensity occurred over the Gulf of Mexico at 105 kt (about 121 mph) with the same reported minimum pressure of 953 mb during 0000–0600 UTC 9 October, just before weakening prior to U.S. landfall.

Delta produced significant storm surge and heavy rain in several locations. Storm surge inundation of about 6–9 ft above ground level occurred east of landfall in coastal Vermilion, Iberia, and St. Mary Parishes, Louisiana; a temporary gauge at Freshwater Canal Locks recorded 9.45 ft above normal tide (about 8.5 ft above MHHW) before the sensor reached its limit. Cypremort Point and nearby sites reported peak water levels near 8.0 ft MHHW. Calcasieu Pass and Holly Beach recorded peaks of about 5.6 ft and 5.1 ft MHHW, respectively. Rainfall was heaviest in southwestern and central Louisiana, with widespread 15–20 inch totals between Lake Charles and Alexandria and a site near LeBleu Settlement reporting 17.57 inches; Baton Rouge received nearly 10 inches. The Yucatán Peninsula saw 4–8 inches in the north around Cancún with localized flooding.

Confirmed fatalities numbered four in the United States: two direct deaths by drowning in rip currents near Destin, Florida, and two indirect deaths in Louisiana related to electrocutions and fires during preparations and cleanup. In Mexico’s Yucatán Peninsula there were two indirect fatalities during cleanup. The NOAA damage estimate for the U.S. is about $2.9 billion (USD), with most damage in Louisiana—additional wind and roof damage in areas still recovering from Hurricane Laura and substantial inland and flash flooding. Mexico’s estimated damage was about $185 million (USD), including flooding and pier/hotel impacts around Cozumel, Playa del Carmen, and Punta Cancun.

Notable aspects include an exceptionally rapid intensification in the western Caribbean early in Delta’s life—a 90-kt increase in 36 hours, a rate rare in the satellite era—followed by an abrupt weakening before the Yucatán landfall. Forecasting tracked the storm well overall, but intensity forecasts missed the initial rapid intensification and the quick subsequent weakening; the track forecasts showed a northward bias early on because the storm’s center unexpectedly reformed. NHC storm surge forecasts successfully highlighted the 7–11 ft inundation threat in parts of coastal Louisiana, and observations verified peak inundation near the forecasted range.