Flood — Lebanon, Pennsylvania

2011-09-07 to 2011-09-11 · near Lawn, Lebanon, Pennsylvania

Event narrative

Swatara Creek at Harper Tavern crested at record/major flood stage, 24.46 feet. Flood stage is 9.0 feet. This is the 2nd highest crest on record.

A 55-year old man was swept away in floodwaters from Route 72 just north of Frog Hollow Drive in Swatara Township. He was trapped in rising waters on Swatara Creek.

The Lebanon County Emergency Management Agency fielded 4,500 calls, normal calls number 200. Another man attempted to warn motorists of the high water potential when he was struck and killed by a vehicle on West Cumberland Street in North Lebanon Township.

The Quittapahilla Creek was out of its banks and flooding roadways around Annville. Cleona Borough reported significant flooding from this creek. Dozens of homes experienced several feet of water in basements. All bridges over this creek were under water.

Major flooding occurred in the Palmyra area with numerous dispatches for help.

Lebanon City and Myerstown had many flooded roads with stranded cars.

All major routes in and out of Jonestown were closed. Interstate 81 was closed near Swatara Creek. A preliminary total of 148 structures were destroyed, 1601 suffered major damage, and 701 minor damage with a total of 3398 structures impacted. Damage was estimated at $2,030,985 for public facilities.

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 → (40.2195, -76.5421)

Source: NOAA Storm Events Database, event_id 348448. Narrative written by the NWS forecast office that issued the report.