page_title: Meteorological history of Hurricane Dennis
section_title: Gulf of Mexico and dissipation
hierarchical_section_title: Meteorological history of Hurricane Dennis / Gulf of Mexico and dissipation
caption_attribution_description: Hurricane Dennis was bearing down on the Gulf Coast of the United States on July 10, 2005, at 12:15 p.m. (16:15 UTC) when the Moderate Resolution Imaging Spectroradiometer on NASA's Terra satellite captured this image. With winds of 140 miles per hour (225 kph), Dennis was a powerful Category 4 storm just hours away from making landfall. At the time this image was taken, the eye of the storm was about 55 miles (90 kilometers) south, southeast of Pensacola, Florida, and the storm was moving northwest at about 18 miles per hour (29 kph). The size of the storm put clouds of rain over most of the southeastern United States well before the storm came ashore. In this image, Dennis covers all of Florida, Alabama, Mississippi, and stretches over parts of Louisiana. The northern fringes of the storm appear to be over Tennessee and North Carolina. For additional information and warnings about this storm, please visit the National Hurricane Center. This image has been cropped from its original version. This image is available in additional resolutions from the MODIS Rapid Response Team.
context_page_description: The meteorological history of Hurricane Dennis spanned twenty-two days, beginning with its inception as a tropical wave over Africa on June 26, 2005, and terminating with its dissipation on July 18 over the Great Lakes of North America. The incipient wave that became Dennis emerged over the Atlantic Ocean on June 29 and moved briskly to the west. Dry air initially inhibited development, though once this abated the wave was able to consolidate into a tropical depression on July 4. The depression soon crossed Grenada before entering the Caribbean Sea whereupon increasingly favorable environmental factors, such as low wind shear and high sea surface temperatures, fueled intensification. Turning west-northwest, the system achieved tropical storm status on July 5 and hurricane status the following day.
  Formation of a well-defined eye and central dense overcast signaled Dennis's intensification into a major hurricane. The powerful storm soon struck Granma Province, Cuba, as a Category 4 early on July 8; violent winds battered the province and caused extensive damage.
context_section_description: Maintaining its northwesterly course, Dennis emerged over the Gulf of Mexico just north of Havana around 05:00 UTC on July 9. Prolonged interaction with the mountains of Cuba severely disrupted the hurricane's core, though it managed to retain a ragged 14 mi (23 km) wide eye. By the time Dennis emerged over water, its maximum winds fell to 85 mph (140 km/h) and its pressure rose to 973 mbar (hPa; 28.74 inHg). Situated along the western periphery of a ridge, a gradual turn to the north-northwest ensued. A cool eddy temporarily halted notable reorganization; however, once Dennis cleared this eddy it was able to strengthen. Starting at 18:00 UTC, the hurricane underwent rapid intensification "at a rate that bordered on insane", as described by forecaster Jack Beven. In the subsequent 18 hours, its central pressure fell by 32 mbar (hPa; 0.95 inHg), including a drop of 11 mbar (hPa; 0.32 inHg) in 1 hour and 35 minutes. Hot towers extending to 10 mi (16 km) were observed during the strengthening. The intensification culminated with Dennis attaining winds of 145 mph (230 km/h) at 06:00 UTC on July 10 and reaching its lowest pressure of 930 mbar (hPa; 27.47 inHg) at 12:00 UTC. This ranked Dennis as the strongest pre-August hurricane in the Atlantic basin; however, this was eclipsed just six days later by Hurricane Emily which was the first July Category 5 on record. At this time, the hurricane was situated roughly 180 mi (290 km) southwest of Tallahassee, Florida. Although Dennis featured a large circulation with tropical storm-force winds extending up to 230 mi (370 km) from its center, its core was compact and hurricane-force winds only stretched 40 mi (65 km) outward.
  During the latter part of July 10, Dennis traversed an area with lower ocean heat content. Coupled with entrainment of mid- to upper-level dry air, notable weakening took place as the hurricane approached the Florida Panhandle. Around 19:30 UTC, Dennis made its third and last landfall as a major hurricane over Santa Rosa Island, between Navarre Beach and Gulf Breeze, with estimated winds of 120 mph (195 km/h) and a pressure of 946 mbar (hPa; 27.94 inHg). A Florida Coastal Management Program tower in Navarre observed sustained winds of 99 mph (159 km/h) and a gust to 121 mph (195 km/h). Dramatic weakening ensued once the hurricane moved onshore, with winds falling below tropical storm-force in just 12 hours. Upon weakening to a depression on July 11, handling of operational advisories was transferred from the NHC to the Weather Prediction Center (formerly the Hydrometeorological Prediction Center).
  The lingering depression continued north-northwest through the Mississippi River Valley and gradually slowed. Weakening steering currents caused Dennis to slow and turn northeast as it traversed the Ohio River Valley on July 12–13. Dennis's circulation became elongated and the system degenerated into a non-convective remnant low by 12:00 UTC on July 13 as it moved across Illinois. Thereafter, the cyclone executed a prolonged clockwise loop over the state before accelerating northeast on July 16. During this period, a band of heavy precipitation set up over the southern Appalachian Mountains; record rain fell across northern Georgia, with localized totals exceeding 10 in (250 mm). The remnants later crossed the Great Lakes before being absorbed into a larger extratropical cyclone over Ontario on July 18.
caption: Hurricane Dennis hours before making landfall along the Florida Panhandle on July 10
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