Flood — Lancaster, Pennsylvania

2011-09-07 to 2011-09-11 · near Denver, Lancaster, Pennsylvania

Event narrative

The Susquehanna River at Marietta crested in major flood stage at 58.16 feet. Flood stage is 49.0 feet. This is the 4th highest crest on record. The Conestoga River at Lancaster crested in major flood stage at 21.30 feet. Flood stage is 11.0 feet. This is the 2nd highest crest on record.

Life-threatening flash flooding affected a large part of western Lancaster County, inlcuding Elizabethtown, Manheim, Marietta and Columbia.

Mudslides, trapped motorists and flooded homes were widespread from Elizabethtown to Columbia in northwest Lancaster County. Mount Joy and Marietta also experience major flooding.

At one point on the afternoon of the 8th, emergency dispatchers were handling more than a call per minute from stranded drivers and homeowners experiencing flooding. The flooded roadways severely limited responders' ability to reach those in need. In Elizabethtown the only north-south road accessible was Mount Joy Road. A particularly dangerous water rescue occurred at 5pm when Maryland State Police helicopters rescued six motorists after their vehicles (large trucks) became disabled on East Main Street in Mount Joy. Multiple vehicles were stranded on Route 30 westbound at Prospect Road, west of Mountville. Mudslides closed parts of Route 441 and Elizabethtown Road. Most of the above mentioned Townships declared States of Emergency during this flood. 20 municipalities in total declared disasters. Cocalico Creek raged out of its banks during this event, flooding many locations in Ephrata Borough and Township. At least 20 homes were condemned there, including an apartment building. Water covered the bridge and all of Main Street.

Major flooding occurred along Chickies Creek in and near the Manheim area. The southern side of Manheim was underwater from flooding along the creek, resulting in a significant number of structures flooding. Route 72 was underwater from the creek. At one point, cars were described as 'floating' down Main Street in Manheim. The Twin Kiss restaurant at Fruitville Pike and Main Street was partially submerged under about 4 feet of water. Mayor Eric Phillips described Manheim as almost an island surrounded by rising floodwaters at one point during the storm. The Manheim Twin Kiss, a Manheim institution here for decades, had 3 feet of the water wash through it which toppled commercial refrigerators and other massive objects. In West Hempfield Township, a crew in boats helped a couple evacuate their home near Siegrist and Farmdale roads.

The 156 year-old Siegrist's Mill Bridge in Rapho Township was lost, as it was ravaged by flood waters from Chickies Creek on the afternoon of the 8th. During Agnes, the bridge shifted a few feet and was cemented back into place. Two other county-owned covered bridges, as well as two other conventional bridges, were closed for repairs because of the storm damage. They included Little Chickies No. 2 on Pinkerton Road, Little Chickies No. 4 on Drager Road, Big Conestoga No. 6, also called the Pinetown covered bridge on Bridge Road and Little Conestoga No. 1 on Shreiner Station Road.

Flooding along the Susquehanna was also reported in the Marietta area. Structure flooding was widespread along several streets near the river. A traditional Marietta measuring stick, at Shank's Tavern on Front Street, showed a watermark about 3 feet up the structure. That mark was a couple feet short of archived watermarks from a 1936 flood and the Hurricane Agnes flooding of 1972.

On the Conestoga River, Lancaster city officials evacuated residents from low-lying areas of Almanac Avenue and South Broad Street, near the river. Crews also evacuated 25 people from Conestoga Boulevard in Conestoga Township, going door to door to ask them to leave their homes. Hundreds of roads were closed across the county, a county dispatch supervisor said. Parts of major routes were closed, including routes 222, 30, 23, 72, 441, 230, 322, 741 and 772.

PPL ordered the evacuation of its Holtwood Hydroelectric Plant on Thursday afternoon. The generating plant was shut down and about 20 plant employees were evacuated, beginning about 4 p.m. Another 80 workers involved in the ongoing $434 million expansion of the plant also were evacuated. The last time the hydroelectric plant went through an emergency shutdown and was evacuated was probably during Agnes, a PPL spokesman said.

Three deaths were noted in Lancaster County. A 62-year-old woman in a vehicle became stranded on Route 322 near Pumping Station Road in Elizabeth Township Thursday morning. Her car was swept away in the water and submerged. An 8-year-old boy playing in a flooded backyard in East Cocalico Township was swept off his feet by the water. His head became caught in a submerged storm drain, where he was found by emergency personnel. He was taken to Ephrata Community Hospital, where he was pronounced dead. A man was swept away as he tried to walk through water just off White Oak Road, near the border of Rapho and Penn townships.

A preliminary total of 32 structures were destroyed, 395 suffered major damage, and 1339 minor damage with a total of 1782 structures impacted. Damage was estimated at $818,110 for public facilities. A total of 189 water rescues were performed.

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 → (40.2408, -76.1380)

Source: NOAA Storm Events Database, event_id 348420. Narrative written by the NWS forecast office that issued the report.