Tropical Storm — Okeechobee, Florida

2017-09-10 to 2017-09-11 · Okeechobee, Florida

Event narrative

Category 3 Hurricane Irma made landfall near Naples during the late afternoon of September 10. Irma then moved northward across west-central Florida during the evening while weakening to a Category 2 hurricane approximately 60 miles west of Okeechobee. A long duration of damaging winds occurred across Okeechobee County, with a period of gusts to minimal hurricane force. The highest measured sustained wind was recorded at the Okeechobee Airport ASOS (KOBE; 46 mph from the southeast at 2215LST on September 10) and the highest measured peak gust was 71 mph at 2035LST. A preliminary damage assessment from the county listed 585 affected residential structures, with an additional 239 with minor damage, 99 with major damage and 8 destroyed. The total estimated damage cost was $157 million. Damage occurred primarily to roof shingles, soffits, awnings, and pool enclosures. Mobile homes experienced more extensive structural damage. Many trees were uprooted or snapped.

Wider weather episode

Hurricane Irma moved northward over the far western Florida peninsula between the afternoon of September 10 and the morning of September 11 at Category 1-2 strength. During the closest point of approach to east-central Florida during the early morning hours of September 11, rain bands associated with the inner core elongated west-to-east and lifted through northwest Osceola County, Lake County and western Orange County. Due to the large size of the wind field, a long duration of damaging tropical storm force winds with gusts to hurricane force was experienced across all of east-central Florida. There were no direct hurricane-related fatalities, however 10 indirect fatalities occurred during the evacuation and recovery phases of the hurricane. Preliminary damage estimates across east central Florida exceeded $1.3 billion.

A storm surge of 2-3 feet affected the coast of Martin, St. Lucie and Indian River Counties, and 3-4 feet of storm surge impacted the coast of Brevard and Volusia Counties. Moderate to major beach erosion occurred along the entire east-central Florida coastline. Water levels rose within the coastal lagoon system generally rose between 1 and 3 feet (although locally up to 4.5 feet within a few constricted areas of the lagoon, primarily within north Brevard and Volusia Counties) due to coastal surge and run-off from heavy rain and slow drainage to the Atlantic through the inlets. River flooding caused to enter some homes adjacent to the Halifax River, primarily in Ormond Beach, Holly Hill and north Daytona Beach. Many docks and boat houses along the Indian, Banana and Halifax Rivers were damaged from the combination of high water and wave action.

Rainfall totals of 10-15 inches were widespread across east-central Florida. The highest totals occurred in a swath from northern St. Lucie County to far southern Indian River County, where accumulations reached 15 to nearly 22 inches. A significant portion of this rain fell during the early morning hours of September 10 as excessive rain bands trained onshore ahead of the main rain area associated with Hurricane Irma. Flooding entered several homes and many roadways became impassible. Hurricane rain bands also resulted in flooding of homes and roadways in many other areas later on September 10, including Fellsmere (Indian River County) where a dozen people were rescued from flood waters and north Merritt Island (Brevard County) where water approached or entered several homes. During the early morning hours of September 11, flooding breached several hundred homes and resulted in the rescue of 200 residents in Orlo Vista (Orange County) when a lake and adjacent retention ponds overflowed.

Widespread heavy rain fell within the St. Johns River basin and caused the entire river (from Cocoa in Brevard County to Astor in Lake County) to reach flood stage. The Astor area was the first to reach flood stage during the afternoon of September 10, then Cocoa very early on September 11 and Lake Harney that evening, Deland very early on September 12 and Sanford very late on September 14. All points along the river eventually reached moderate to major flood stage, impacting adjacent homes, structures, property and roadways. The river remained in flood for well over one month.

Ten tornadoes were confirmed, including eight within Brevard County (one EF-0, six EF-1, and one EF-2), one in Volusia County (EF-1) and one in Lake County (EF-1). Additional tornadoes likely occurred, however it was impossible to distinguish weak, short track tornado damage from the overall widespread, background wind damage of similar velocities.

Source: NOAA Storm Events Database, event_id 719495. Narrative written by the NWS forecast office that issued the report.