Tropical Storm Isaac 2012 in Sebastian, Florida

Isaac never made landfall in Florida, but its rainbands dropped storm totals of up to 16.50 inches on southern Indian River County between August 25 and 28, 2012, and spun up an EF-0 tornado in Vero Beach on August 27 (NWS Melbourne).

The storm passed to the west of Key West into the Gulf of Mexico, and NWS Melbourne records that its greatest impacts on east-central Florida came on Sunday and Monday, August 26 and 27; Isaac became a Category 1 hurricane only early on August 28, over the Gulf, before landfall on the Louisiana coast (NWS Melbourne). The Florida Climate Center put it plainly: while Isaac never directly hit Florida, its size spread the impacts over a large portion of the state (Florida Climate Center). In Indian River County it was a tropical storm, felt as rain and squalls rather than as a landfall.

Sebastian itself barely appears in the record. The city shows up as Sebastian Inlet, the point where the National Hurricane Center started and stopped its watches and warnings, and no rain gauge or damage report from Sebastian appears in the readable NOAA summaries. The measured effects in Indian River County cluster around Vero Beach, Vero Beach South and Grovenor Estates, so this page is built around the county record.

Sebastian Inlet was the northern breakpoint for Isaac's east coast tropical storm warning from August 25 until the evening of August 26, 2012, with a watch north of the inlet to Flagler Beach (NHC Tropical Cyclone Report).

The National Hurricane Center advisory issued at 11 a.m. EDT on August 25 announced that the tropical storm warning had been extended northward along the Florida east coast to Sebastian Inlet, and that a tropical storm watch had been issued north of Sebastian Inlet to Flagler Beach (NHC advisory 18). At that moment the center of Isaac was still near eastern Cuba.

The hurricane center's table shows the watch north of Sebastian Inlet discontinued at 2100 UTC on August 26, and then, at 0300 UTC on August 27, the warning modified to run from Jupiter Inlet to Tarpon Springs (NHC table, page 62). Read in Eastern Daylight Time, the coast from Sebastian Inlet south to Jupiter Inlet left the warning at 11 p.m. on August 26, about 12 hours before the Indian River County tornado touched down.

An EF-0 tornado with peak winds estimated at 80 to 85 mph crossed 1.6 miles of west Vero Beach between 11:03 and 11:05 a.m. EDT on August 27, 2012, damaging 95 structures, mostly mobile homes (NWS Melbourne tornado survey).

The survey, done on the morning of August 28, traces the path in detail. The tornado first touched down just southeast of Indian River County Fire Station Number 7 on 12th Street in Vero Beach, left a discontinuous track through the Vero Beach Estates and Countryside Village mobile home parks, crossed State Road 60, and lifted just north of the Paradise Park residential area (NWS Melbourne). Of the 95 damaged structures, 62 received minor damage and 33 sustained major damage from wind and rain, much of it from debris off adjacent carports and entryway awnings. Indian River County Emergency Management and Fire Rescue officials assisted with the survey.

The tornado formed in a persistent rainband that had become anchored along the east coast of central and southern Florida (NWS Melbourne, page 2). It was one of five tornadoes Isaac produced in Florida, all of them rated EF-0, according to the National Hurricane Center (NHC report, page 8). The Florida Climate Center's August 2012 summary records the same Indian River County tornado as touching down near Vero Beach on the 27th (Florida Climate Center).

A gauge 5.2 miles south of Vero Beach caught 16.50 inches between August 25 and 28, 2012, the highest storm total in the NWS Melbourne table, which lists no gauge in Sebastian (NWS Melbourne rainfall table).

NWS Melbourne states that the heaviest rain from Isaac fell over the southern part of east-central Florida, with moderate flooding and temporary closure of several roadways in Martin, St. Lucie, Indian River and Okeechobee counties (NWS Melbourne). The same 16.50 inch total for the FL-IR-32 gauge appears in the National Hurricane Center's report. The gradient was steep: the Vero Beach airport logged 7.57 inches, while the Melbourne airport, in Brevard County north of Sebastian, logged 1.69 (NWS Melbourne, page 7). The table therefore describes the Vero Beach area of Indian River County rather than Sebastian.

One day stood out at Vero Beach. The Florida Climate Center lists 6.50 inches of rain at Vero Beach on August 27, 2012, matching the daily record of 6.50 inches set in 1949 (Florida Climate Center, page 2).

The strongest wind measured at the Vero Beach airport during Isaac was a 45 knot gust, about 52 mph, at 0244 UTC on August 27, 2012, which was 10:44 p.m. EDT on August 26 (NWS Melbourne).

The airport station, KVRB, recorded its highest two-minute sustained wind of 37 knots from 140 degrees at 0245 UTC and its lowest sea level pressure of 1009.4 mb at 0237 UTC (NWS Melbourne wind table). The National Hurricane Center lists the same 45 knot Vero Beach gust and the same 7.57 inch storm total (NHC report, page 23). At 1.15 mph per knot, 37 knots is about 43 mph, well short of hurricane force, which fits Isaac's status as a tropical storm while it passed Indian River County.

The rain and cloud also held temperatures down. The Florida Climate Center lists a Vero Beach high of only 83 degrees on August 26, 2012, breaking the record low maximum of 85 set in 1997 (Florida Climate Center, page 5).

No readable source gives a separate damage dollar figure for Sebastian or Indian River County; the National Hurricane Center's estimate of about $2.35 billion in total U.S. damage covers the whole storm across the United States (NHC report, page 9).

The hurricane center estimates insured U.S. damage at about $970 million, with about $407 million more paid by the National Flood Insurance Program (NHC report, page 9), and it notes that wind damage in southern Florida and the Florida Keys was minor and mostly limited to downed trees and power lines (NHC report, page 10). The worst Florida flooding was not in Indian River County but in Palm Beach County, in Wellington and The Acreage. Against that statewide picture, the Indian River County record for Isaac comes down to the 16.50 inch gauge south of Vero Beach, the Vero Beach airport readings and the 95 structures damaged by the August 27 tornado.