Coastal Flood — New Castle, Delaware

2012-10-30 · New Castle, Delaware

Wider weather episode

Post Tropical Storm Sandy caused an estimated $5.5 million dollars of damage across the three counties in Delaware. The damage estimates from the state were broken down to $2.8 million in New Castle County, $832,000 in Kent County and $1.9 million in Sussex County. Damages were due to tidal flooding as significant wave action resulted during multiple high tide cycles, due to increasing onshore winds prior to landfall. Damages were also due in part to inland flooding caused by excessive rainfall, as up to 10 inches of rain were reported. In addition, high winds resulted in many trees and wires coming down statewide. This created 100,000 power outages and resulted in many road closures due to downed trees and flooding. The hardest hit county was New Castle County. All power was restored by November 2nd. No direct deaths or injuries were reported in Delaware due to the storm and the overall number of traffic accidents were low because of driving restrictions.

Tropical Storm Sandy formed in the Caribbean Sea on the 22nd of October. After drifting slowly southwest into the 23rd, Sandy turned to the north and intensified to a hurricane on the 24th just before making landfall in Jamaica during that afternoon. Hurricane Sandy continued to the north and intensified to a strong category two hurricane before making landfall again in Cuba shortly after Midnight EDT on the 25th. Hurricane Sandy emerged on the other side of Cuba during the morning of the 25th and proceeded to drift northwest as a category one or two hurricane as it moved through the Bahamas on the 25th and 26th. Overnight on the 26th, Hurricane Sandy (Category 1) started to move toward the north-northeast, a motion that continued into the evening of the 28th. From there, Sandy's motion became driven by two factors. An anomalously strong blocking ridge over the Canadian Maritimes prevented Sandy from escaping to the east. Simultaneously, an approaching and deepening middle latitude trough was about to capture Sandy. The combination of the two, turned Sandy to the north overnight on the 28th and then to the northwest on the 29th. Hurricane Sandy received one last jolt of tropical energy as it passed across the Gulf Stream during the morning of the 29th. The lowest recorded central pressure of 940 millibars (27.76 inches) occurred when Category 1 Hurricane Sandy was about 110 miles southeast of Atlantic City at 2 p.m. EDT on the 29th. As Sandy continued to move northwest and interact with the mid latitude trough, its interaction continued to make it less tropical, but did not weaken it much. Sandy continued to make a harder turn to the left (west) and made landfall in Atlantic County as a post tropical storm in Brigantine City just north of Atlantic City at 730 p.m. EDT on the 29th. The estimated minimum central pressure was 945 millibars. The lowest recorded central pressure was 945.6 millibars at the Atlantic City Marina at 734 p.m. EDT. From there, Sandy continued to weaken or fill as it moved west. At 9 p.m. EDT, the low pressure system was in western Atlantic County and continued to move west-northwest. At 11 p.m. EDT, the post tropical storm (about 954 millibars) was located in southern Chester County. Post tropical storm Sandy continued to move west-northwest and weaken. At 2 a.m. EDT on the 30th, the 962 millibar low was located near Harrisburg, Pennsylvania and at 8 a.m. EDT the 979 millibar low was near Altoona, Pennsylvania. From there, the rapidly weakening low pressure system moved northwest and reached Lake Erie (993 millibars) at 8 p.m. EDT that evening and from there drifted north into Canada.

Prior to Sandy's arrival, Governor Jack Markell declared a State of Emergency and ordered a mandatory evacuation of 50,000 coastal residents in areas three quarters of a mile from the shore line and other low-lying coastal communities in Sussex, Kent, and New Castle Counties. Approximately 50,000 people evacuated. President Barack Obama also signed a federal emergency declaration for Delaware. The mandatory evacuations were ordered effective at 8 p.m. EDT on the 27th, with completion by 8 p.m. EDT on the 28th. Businesses within the mandatory evacuation zones were also ordered to close by 6 p.m. EDT on the 28th. In addition, mandatory evacuations were also ordered for some residents in Wilmington, covering the southeast portion of the city, near the Delaware River. To expedite evacuations, tolls on northbound Route 1 were suspended by the Delaware Department of Transportation (DelDOT). However, around dawn on Sunday morning the 28th, a dune breach occurred and forced the closure of a section of Delaware Route 1 in Sussex County in both directions north of the Indian River Inlet Bridge. This closure forced residents evacuating from Bethany Beach, South Bethany, and Fenwick Island to detour inland onto secondary roads. Following the completion of evacuations, Governor Jack Markell enacted a Level 2 Driving Restriction on all Delaware roads, allowing only emergency and essential personnel access after 5:00 a.m. EDT on Monday the 29th. All schools and universities were closed on the 29th. Traffic managers advised that bridges over the Chesapeake and Delaware canals would be closed when winds reached 50 miles per hour in the area. In addition to these preparations, several shelters were opened throughout the state, including two each in New Castle and Kent Counties, with three in Sussex County. On the 30th, the governor reduced driving restrictions to level 1: for safety, emergency or business purposes only. On the 31st, service resumed on the Cape May-Lewes Ferry and state parks reopened. On November 1st, the University of Delaware resumed classes and DART buses were back in service. There were still about thirty roadways that were still closed.

In New Castle County, evacuations occurred as far north along the Delaware River as the southeast part of Wilmington. The worst tidal flooding occurred south of Port Penn and affected Augustine Beach the hardest. Dozens of trees were uprooted in Wilmington. About 35 roads were closed because of flooding or high wind. Most of them were near the Delaware Bay including Delaware State Route 9. In Kent County, duning withstood the tide and wave action. Nevertheless, both Kitts Hummock and Bower Beach lost several feet of sand and cliffs as high as four feet. Woodland Beach was flooded. About forty roads were closed because of flooding or high wind.

Sussex County was hit hard by tidal flooding and wave action. Waves at Bethany Beach reached 12 feet. Delaware State Route 1 south of Dewey Beach remained closed until November 4th. The dune breach brought 4 to 6 feet of sand onto the roadway and one approach road in the area of Indian River Inlet was destroyed. During the height of the storm Rehoboth and Dewey Beach were under water. All roads leading in and out were impassable. Prime Hook Beach was also impassable. Bethany Beach and Fenwick Island were hit the hardest along the coast. Tidal flooding also closed several roadways in Oak Orchard starting with the morning high tide on the 28th. Tidal flooding also affected Lewes. Trees were uprooted in Georgetown and a roof collapsed in Greenwood. About forty roadways were closed in the county and both the Cedar Creek Drawbridge and Fowler Beach Road were expected to be closed indefinitely. The annual

Rehoboth Beach Halloween bash was cancelled.

In the Lower Delaware Bay, minor tidal flooding started during the high tide cycle on the morning of the 28th, with some moderate tidal flooding during the high tide cycle on the evening of the 28th. In Upper Delaware Bay and tidal sections of the Delaware River, some minor tidal flooding occurred during the evening high tide cycle on the 28th, with moderate (upper Delaware Bay) tidal flooding occurred during the one overnight high tide cycle on the 29th as Sandy moved westward. The storm surge averaged 4 to 5 feet. In the Delaware Bay and into the lower tidal Delaware River, the high tide at Reedy Point (New Castle County) reached 9.1 feet above mean lower low water during the evening high tide on the 29th. It was the second highest tide on record, the record is 9.2 feet above mean lower low water set during the April 16, 2011 nor'easter. Some lesser but still moderate tidal flooding occurred with the high tide cycle during the middle of the day on the 30th. The high tide at Breakwater Harbor (Sussex County) reached 8.71 feet above mean lower low water during the morning high tide on the 29th. This is the third highest tide on record, the record is 9.2 feet above mean lower low water set during the March 6, 1962 nor'easter. Each subsequent high tide cycle had lower peaks.

Heavy rain fell across the state as Sandy approached and moved over the region. This made it easier for shallow rooted and leafed trees to be uprooted and it also complicated the tidal flooding. Event rainfall totals ranged from around 5 inches in northern parts of the state to around 10 inches in southern areas. The steady rain associated with Sandy spread into Delaware during the day on the 28th and slowly progressed north. The heaviest rain fell overnight on the 28th into the early evening of the 29th. The rain ended during the middle of the day on the 30th.

Peak wind gusts included 67 mph in Stones Throw (New Castle County), 66 mph at Breakwater Harbor (Sussex County), 59 mph in Reeves Crossing (Kent County), Appoquinimink (New Castle County) and Lewes (Sussex County), 58 mph at the intersection of Route 1 and Route 16 (Sussex County), 56 mph at the New Castle County Airport (New Castle County), 54 mph at the Dover Air Force Base (Kent County), 50 mph at the Georgetown Airport (Sussex County) and 46 mph in Cedar Creek (Sussex County). Strong winds overspread the state during the morning of the 29th, with high winds occurring during the late afternoon and evening of the 29th. Winds quickly diminished overnight and were relatively light by sunrise on the 30th.

Source: NOAA Storm Events Database, event_id 417506. Narrative written by the NWS forecast office that issued the report.