Flood — Dauphin, Pennsylvania

2011-09-07 to 2011-09-11 · near Deodate, Dauphin, Pennsylvania

Event narrative

Swatara Creek near Hershey crested at major flood stage, 26.8 feet. Flood stage is 7.0 feet. Swatara Creek at Middletwon crested at major flood stage, estimated at 26.30 feet. Flood stage is 11.0 feet. This is the 5th highest all time.

The Susquehanna River at Harrisburg crested in major flood stage at 25.17 feet. Flood stage is 17 feet. This is the 5th highest crest on record.

While the Susquehanna River flooded a large area of Harrisburg, some areas were fortunate enough to escape the flood waters. Midtown and Uptown residents were largely unscathed, though widespread power outages were reported. The river levels crested several feet below that of Agnes, thanks in part to less contribution from the West Branch of the Susquehanna.

Between 8,000 and 10,000 residents were evacuated. The Shipoke area of downtown reported significant flooding. City Island was also hard hit, with the baseball stadium under at least seven feet of water, prompting the double A baseball team to have to play its playoff games on the road.

Major damage was widespread in Hershey. Hersheypark and ZooAmerica both reported major damage with 8 feet of water in low lying areas of Hershey Park. Many structures were flooded and many roads suffered damage. A ramp off of Route 322 near the Penn State Hershey Medical Center had a 3-foot deep trench cut across the road. Swatara Creek cut a wide and devastating flood path. Evacuations were noted in Palmyra, Derry Township and Middletown.

A 70-year old man died when a basement wall collapsed on him in Derry Township. He was pumping water from his flooded basement. A second man died in flood waters. While details surrounding his death are unknown, his mud covered car and body were found in Swatara Township several days after the flooding. A third man, 81 years old, drowned after his car was washed into Clarks Creek in Middle Paxton Township. Finally, a fourth victim, a 54 year old female, was swept away by flood waters. Her body was recovered weeks later in Swatara Creek.

Water rescues were widespread in Dauphin County. One county rescuer was quoted, 'We were rescuing people on the way to rescuing people,' Leonard said. 'There was no time for introductions or salutations. We were dispatched every 90 seconds for hours.'

Severe flooding occurred on Spring Creek. House flooding, closed roads and water rescues using boats were conducted in Paxtang Borough and Swatara Township. Three-quarters of all roads were flooded in Derry Township. Middletown on the mouth of Swatara Creek, where it enters the Susquehanna River also reported major flooding. Five of the eighteen homes on Few Avenue were condemned from flood damage. The basements of these homes were visible from the street through giant holes in the foundation. Residents also reported a foul smell after the floods, with one resident saying, 'Imagine the contents of a septic tank mixed with diesel and fuel oil.'

A preliminary total of 295 buildings were destroyed, 1040 suffered major damage, and 1273 suffered minor damage with a total of 3348 structures impacted. Overall damage was estimated at $150 million. In addition, 368 acres of crops were destroyed with an estimated value of $700,000.

Wider weather episode

Heavy rainfall from the remnants of Tropical Storm Lee produced widespread flooding, flash flooding and river flooding mainly near and to the east of the Susquehanna Valley from September 4-10. Several locations in the Susquehanna Basin came close to records set by Hurricane Agnes (June 1972) and a few points (Bloomsburg, Hershey and Loyalsockville) set new floods of record. Flooding along Swatara Creek resulted in property damage and several deaths. Severe flooding occurred along Loyalsock Creek and many points along the main-stem of the Susquehanna River. The interaction of a stalled frontal boundary over the Mid-Atlantic region, a strong northern stream short-wave (with a persistent jet entrance region) and deep tropical moisture associated the remnants of Tropical Storm Lee resulted in multi-day, significant heavy rainfall event over Pennsylvania.

Tropical storm Lee was the twelfth named storm of the 2011 season forming over the Gulf of Mexico on September 1. A strong northern stream short-wave interacted with Lee causing the storm to re-curve to the north-northeast. By 1200 UTC September 6, having undergone extra-tropical transition, post-tropical Lee was located over northern Georgia. The surface low weakened as it moved up the Appalachian Mountain chain. However, the strong low-level flow and the above normal precipitable water produced an extensive, north-to-south oriented band of heavy rainfall.

The rainfall associated with the remnants of Lee produced the 4th largest flood of record in the Mid-Atlantic Region. The five-day storm rainfall totals for September 5 to 9 were generally in the 5-8 inch range over the mid-section of central Pennsylvania and in the 8-12 inch range in the Susquehanna Valley region. There were local amounts reported in excess of 15 inches east of the Susquehanna River. The local climate sites in Harrisburg (KMDT) and Williamsport (KIPT) reported 13.44 and 9.03 inches respectively. On September 7, 2011 both KMDT and KIPT set their all-time daily (24-hour) rainfall for the month of September at 7.71 and 6.76 inches respectively. These sites later went on to break the all-time monthly (September) and annual precipitation records, making 2011 the wettest year on record.

View location on OpenStreetMap → (40.2208, -76.5994)

Source: NOAA Storm Events Database, event_id 348413. Narrative written by the NWS forecast office that issued the report.