Danny (2015)

Danny formed from a tropical wave that moved off western Africa on 14 August and became a tropical depression at 0600 UTC 18 August about 1,000 miles east-southeast of the Windward Islands. It moved generally westward across the deep tropical Atlantic while embedded south of the subtropical ridge. After becoming a tropical storm on 18 August, Danny became a hurricane around 1200 UTC 20 August and then underwent rapid strengthening, reaching major hurricane strength by 1200 UTC 21 August. Dry air intrusions and increasing wind shear then caused a rapid weakening, and Danny fell to a tropical depression by 1200 UTC 24 August as it moved through the Leeward Islands; it degenerated into an open wave six hours later.

Danny did not make any landfalls as a hurricane. By the time the system moved through the northern Leeward Islands, the Virgin Islands, Puerto Rico, and Hispaniola on 23–24 August it had already weakened to a tropical storm and then a tropical depression, so there were no hurricane-intensity landfalls reported in the NHC report. Tropical-storm watches and warnings were issued for several islands (Antigua and Barbuda, St. Kitts and Nevis, Anguilla, Montserrat, Saba, St. Eustatius, St. Maarten, Guadeloupe, Puerto Rico, the U.S. Virgin Islands) but were discontinued as the system weakened and moved westward.

Danny’s peak intensity was 110 kt (127 mph) with an estimated minimum central pressure of 960 mb, reached at 1200 UTC 21 August. Aircraft measured an SFMR surface wind of 104 kt and a 12,000-ft flight-level wind of 111 kt during the period near peak intensity; analysis indicates the peak occurred a few hours before the reconnaissance aircraft arrived.

Storm surge and rainfall impacts were minimal. There were no reports of storm-surge damage, and buoy observations recorded wind gusts but no significant coastal inundation. Rainfall from the remnants produced short-lived, generally beneficial rains across the northern Leeward Islands, the Virgin Islands, Puerto Rico, and Hispaniola; the report does not list large rainfall totals at specific cities or counties and notes no significant damage from flooding.

There were no reported deaths or damage associated with Danny. Forecast performance was mixed: NHC track forecasts were notably accurate and performed better than the guidance on average, while intensity forecasts had unusually large errors because several forecasts did not predict Danny’s rapid intensification to a major hurricane on 20–21 August nor its rapid weakening shortly afterward. Danny was a compact Cape Verde–type hurricane whose rapid intensification and subsequent rapid decay, influenced by dry Saharan air and increasing shear, were the most noteworthy aspects.