Flash Flood — Montgomery, Pennsylvania

1999-09-16 to 1999-09-17 · near Countywide, Montgomery, Pennsylvania

Wider weather episode

Hurricane Floyd battered Eastern Pennsylvania (especially Southeast sections around Philadelphia) on September 16th and brought with it torrential and in some places record breaking rains and damaging winds. The hurricane caused widespread flash flooding as storm totals averaged around six inches in the Poconos and Berks County, eight inches in the Lehigh Valley and from eight to twelve inches in the Greater Philadelphia Metropolitan Area. Six people died directly from the hurricane - four drownings and two persons were hit by trees. The hurricane also indirectly contributed to the death of about seven other persons. About 40 persons were seriously injured. There were hundreds of rescues from creeks and trapped/submerged vehicles. Many people ignored barricades and became stranded in flood waters. About 7,000 persons were evacuated, more than half were from Delaware and Bucks Counties, the two hardest hit counties in the state. The Preliminary damage estimate was 60 million dollars. Damage to infrastructure was around 20 million dollars and hundreds of roads and dozens of bridges were damaged or closed. A couple of bridges in Bucks County are not expected to be reopened until 2001. About 200 houses were seriously damaged or destroyed, another 1,000 were damaged but still inhabitable. Over 10,000 homes were flooded. Over 500 apartments were also damaged as were over 100 businesses. The flooding affected fourteen key regional rail service lines around Philadelphia, many were closed and/or damaged. About 501,000 homes and businesses lost power - 412,000 in the PECO Service area in Southeast Pennsylvania, the second worst outage in the company's history. School children were dismissed early. Sewage treatment plants were so overwhelmed with runoff that many spewed raw sewage into the streams and rivers. The first directly related hurricane death occurred in East Nottingham Township in Chester County. A 53-year-old woman was crushed when a tree fell through her house. In Montgomery County three persons drowned in their vehicles when they attempted to drive across flooded roadways. One drove around barricades. A 49-year-old male was found inside his vehicle in the Perkiomen Creek in Perkiomen Valley Park. His disabled vehicle apparently was swept into the creek. A 73-year-old woman was found inside her vehicle in the Wissahickon Creek in Whitemarsh Township. Her vehicle was swept off the road and became pinned against a tree along the banks of the creek. A 47-year-old man in West Conshohocken drowned after he drove around barricades and became stuck in flood waters. His father who was a passenger in the car escaped. In Delaware County, a 67-year-old man drowned in Darby Borough while delivering pizzas. His van was caught in the swirling waters of the Darby Creek. In Philadelphia, a 48-year-old man was crushed by a fallen tree as he was waiting for a green light in Fairmount Park. The torrential rain associated with Floyd contributed to the death of a family (3 persons) on the Pennsylvania Turnpike in Chester County and a 44 year-old man in Upper Pottsgrove Township in Montgomery County. Two other men in Montgomery County (a 61-year-old and a 51-year-old) suffered heart attacks and died while trying to remove water from his basement and while being evacuated. A third (67-year-old) man died of a heart attack in Chester County (West Whiteland Township) while trying to push his vehicle from flood waters on Pennsylvania State Route 100. The highest verifiable storm total was 12.13 inches in Marcus Hook (Delaware County). Philadelphia International Airport not only set a new daily precipitation record of 6.63 inches, but also a new 24 hour record of 6.77 inches. Based on SKYWARN Spotter reports and Doppler Radar precipitation estimates, the area of heaviest precipitation coincided near the "fall line" in Southeast Pennsylvania. The fall line is the boundary between the coastal plain and the Piedmont and represents the first significant rise of the land from near sea level. The onshore flow being lifted over this geographic feature dumped the heaviest rain around this area and fell across northern Delaware and Philadelphia Counties and Lower Montgomery and Bucks Counties. The torrential downpours associated with Hurricane Floyd exceeded the 100-year-flood return period in locations in and around the "fall line" and several rivers and streams either set record or had their second highest crests on record. The combination of winds funneling up Delaware Bay and the river and the record runoff from inland waterways produced moderate tidal flooding at the times of high tide in Delaware, Philadelphia and Bucks Counties. Evacuations occurred in low-lying areas near the river. The evening (16th) high tide also slowed the discharge of streams into the Delaware. The highest wind gusts in most areas were less than 60 mph. But, the combination of the heavy rain that loosened the ground and the persistence of the strong winds uprooted hundreds of trees. Governor Tom Ridge declared a disaster emergency on the 16th. President Clinton declared Bucks, Chester, Delaware, Montgomery and Philadelphia Counties a disaster area. Homeowners in Berks County were also eligible for damage assistance. Hurricane Floyd began as a Cape Verde type hurricane east of the Lesser Antilles. As Floyd moved westward, it passed to the north of and spared both the Greater and Lesser Antilles. Floyd intensified into a Category (Major) IV Hurricane on the Saffir-Simpson Scale. Floyd was also a very large in size hurricane that would prolong the extent of both the torrential rain and high winds. Floyd was heading for Florida before a turn to the northwest spared the state, but Floyd battered the Bahamas. The anticipated turn to the north and the northeast occurred on the 15th as Floyd was heading for North Carolina. Another important synoptic feature was a cold front that was over West Virginia on the 14th. This front stalled in Eastern Pennsylvania on the 15th. The stalled front not only failed to push offshore an already tropical and humid air mass that was over the state, but also acted as a conduit for the tropical moisture associated with Floyd. The moisture headed west toward the front, rising upward along the fall line and dropped the heaviest rain near this geographic feature. Light rain associated with Floyd started in the state on the 15th. The torrential rain associated with Floyd arrived around 5 a.m. EDT in the southern part of the state and spread into the Poconos by 10 a.m. EDT. Floyd was just making landfall at the Mouth of Cape Fear or Bald Head Island in North Carolina as the heavy rain crossed the Mason/Dixon Line. Floyd started to accelerate northeast during the morning of the 16th. Some gusty winds arrived in the state during the morning of the 16th. A weakened (with respect to wind) Category One Floyd moved through Virginia Beach, Virginia and was back over the open Atlantic Ocean around noon on the 16th. Floyd continued to move northeast and the eye passed just east of the Virginia Capes and Fenwick Island, Delaware around 3 p.m. EDT. By the afternoon of the 16th all the torrential rain had moved north of Floyd and ended with the passage of the hurricane (on the same latitude line). During the afternoon of the 16th all of the sustained hurricane force winds were located over the Atlantic. At 5 p.m. EDT Floyd was downgraded to a tropical storm as it passed about 10 miles east of Atlantic City. Between 6 p.m. and 8 p.m. EDT the torrential rain ended across the state. But the strongest winds associated with Floyd mixed down as cooler air behind the system moved into the region. For many locations the strongest wind gusts occurred between 4 p.m. and 10 p.m. EDT and the highest gusts occurred over higher terrain locations. Wind gusts rarely exceeded 50 mph, but all the flooding rains made it easier for trees to be knocked over. Tropical Storm Floyd made landfall again on western Fire Island in Suffolk County, New York around 8 p.m. EDT and was located near Portland, Maine at 8 a.m. EDT on the 17th. Floyd hit Bucks County the hardest, especially in the Neshaminy Creek Basin. The Neshaminy Creek had its second highest crest on record only surpassed by Hurricanes Connie and Diane in 1955. About 2,000 people were evacuated and numerous rescues occurred. In Buckingham Township, 11 school children and the bus driver were rescued after being stranded in the Mill Creek. Twenty-nine homes were destroyed, 80 other were damaged or uninhabitable and 304 others were damaged but still inhabitable. Thirty-two businesses were damaged or destroyed, twelve public buildings or pieces of equipment were destroyed and eighteen public parks were damaged. Flooding was extensive along the Neshaminy Basin from Warrington Township to Bristol Township. In Middletown Township homes along Bridle Drive and Periwinkle Avenue were severely flooded. One house was swept 10 feet off its foundation. Several underground heating oil tanks erupted. In Northampton Township, every bridge over the Neshaminy Creek was closed. Many cars became stranded after driving around barricades. Persons were rescued from car tops. The Langhorne Players Building was destroyed. In Warrington Township five homes along the Little Neshaminy Creek were deemed uninhabitable. The second hard hit area was in townships along the Delaware River as the evening high tide slowed the discharge of streams into the river. Evacuations occurred along the Delaware River in Yardley and Lower Makefield Township, two people were rescued from 10 feet of water. Elsewhere in the county, flooding along the East Branch of the Perkiomen Creek forced the evacuation of downtown Sellersville. In Upper Southampton Township, two homes collapsed because of the heavy rain. Nearly every creek and even some lakes (Silver Lake in Bristol Borough) overflowed. High winds also took their toll. A Perkasie woman was injured trying to remove a downed tree. A fallen tree severely damaged a house in Falls Township. The SEPTA Regional rail service to trenton was stopped because of downed trees on the tracks. Seventy roads were closed and included long stretches of Pennsylvania State Route 611. Seven roads were too damaged to be reopened in Buckingham, Lower Makefield and Upper Makefield Townships. They were still closed on the 25th. Pennsylvania State Route 32 in Solebury Township was expected to be closed indefinitely. Bridges were damaged or washed out in Buckingham, Durham, Solebury, Upper Makefield and Wrightstown Townships. Three bridges were destroyed and were not expected to be reopened until 2001. They are River Road (Pennsylvania State Route 32) over the Jericho Creek in Upper Makefield Township, New Hope Road over the Mill Creek in Buckingham Townships and Swamp Road over the Mill Creek in Wrightstown Township. Delaware County was the second hardest hit county in the state, but no location was hit harder than Darby Borough as flooding along the Darby and Cobb Creeks cut off and decimated the borough. Seven hundred people were evacuated, one hundred were rescued by boat, 11 were plucked from flood waters. The creek devoured residents and businesses along Mill and Walnut Streets. Twenty-five businesses were in ruin; a bank and liquor store disappeared under eight feet of flood water. A delivery van floated into six 2,000 gallon tanks containing toxic solvents, four were recovered. An ice machine was recovered half a mile downstream. The Colwyn section of Lansdowne Borough was also hard hit by the Darby Creek flooding. During the evening of the 16th about 1,000 persons were evacuated in the Crum Creek Valley in Marple, Media, Nether Providence, Ridley, Swarthmore, and Upper Providence Townships. Officials feared the record rainfall would damage the Springton Reservoir Dam's spillway. Other evacuations occurred along the Chester Creek in Aston, Brookhaven, Chester City and Upland Borough. The Chester Creek in Chester had its second highest crest on record since 1971. Tidal flooding also forced the evacuation of about 500 people along the Delaware River in Marcus Hook. Flooding forced evacuations along the Marcus Hook in Upper Chichester Township and Trainer Borough. Intense flooding along Pennsylvania State Route 291 forced the evacuation of 200 people in Tinicum Township. Numerous roads were closed and several were damaged. Two were still closed on the 21st. Numerous water rescues occurred. A Lansdowne firefighter was injured while trying to rescue several children stuck in a tree. A 58-year-old woman was injured when she inadvertently lit an M80 instead of a candle. Mud reached three to four feet high in the business district of Aston Township. The high winds downed numerous trees across the county. One tree damaged a home in Media Borough. Delaware and Chester Counties bore the brunt of the power outages in PECO Energy's service area. In Montgomery County, about 1,500 persons were evacuated. Evacuations occurred in low-lying areas of Abington, Collegeville, Conshohocken, Lower Moreland, Upper Dublin, Upper Moreland and West Norriton Townships. In Upper Dublin Township, 100 residents and 65 children were evacuated after water overflowed the top of the Loch Alsh Reservoir. Numerous water rescues occurred, some from car tops. In Conshohocken, a regional rail car became surrounded by 6 feet of flood waters from the Plymouth Creek quickly. Ten people were trapped. A rescue boat sent capsized and several passengers clung to a tree for a couple of hours before finally being rescued. About 75 persons were rescued from flood waters in Upper Dublin and Springfield Townships, many in the Fort Washington Interchange of the Pennsylvania Turnpike. In Upper Milford Township, a man was rescued after being sucked into an over flow pipe. In Lower Providence Township, a 13-year-old girl was rescued after falling into Mine Run Creek. Ninety-two homes were deemed uninhabitable and 538 others were damaged, but uninhabitable. Ninety-one businesses and 461 apartments were damaged. Hardest hit in the county was Lower Moreland Township. About 100 apartment units in the Huntingdon Valley Condominiums were flooded and contaminated by raw sewage, heating oil and gasoline. All first floor units lost their possessions. The second hardest hit area was along the Schuylkill River from Upper Providence Township south to Conshohocken. In Upper Providence Township, flooding reached the first floor in Port Providence. Numerous trees were knocked down throughout the county and damaged several vehicles. In Chester County, severe and record breaking flooding was reported along the branches and main stem of the Brandywine Creek. In Modena along the West Branch of the Brandywine Creek, twenty households were evacuated, the first evacuations 31 years. Along the East Branch of the Brandywine Creek, a small residential community was leveled in East Bradford Township with losses reaching 90 percent. The flood stage was about 1 foot higher than occurred with Hurricane Agnes in 1972. Gibson's Covered Bridge was severely damaged as trees smashed into hits roof. Farther upstream in Downingtown, twenty homes were severely damaged as fuel oil leaked from their tanks in flooded basements. Fifty other homes were severely damaged and hundreds others had minimal damage. In Phoenixville, thirty people were rescued or evacuated near the Schuylkill River. Severe flooding closed sections of Pennsylvania State Route 100 and United States Routes 1 and 30, especially near the Valley and Brandywine Creeks. Chester County was hit the hardest in the Philadelphia area with respect to wind damage. Houses were damaged by fallen trees in Kenneth Square, Oxford and West Bradford Townships. A PECO linesman was injured after a tree fell on his ladder. Both the East Branch of the Brandywine Creek at Downingtown and the main stem Brandywine Creek at Chadds Ford (Delaware/Chester county line) had record crests, the previous record occurred during Hurricane Agnes in June of 1972. Chester and Delaware Counties bore the brunt of the 412,000 outages in PECO Energy's service area. In Philadelphia, the worst flooding occurred along Cobbs Creek along the Philadelphia/Delaware County border. About 1,000 people were evacuated and 3,500 homes were flooded. Jet skis were used to rescue people. In Manayunk, flooding along the Schuylkill River covered Main Street. Many basements were flooded and one worker was rescued from a flooded basement. Four hundred people were stranded at the Radisson Hotel near the Philadelphia International Airport. Some foundations were undermined in the city's Roxborough section. Numerous trees were knocked down, several damaged vehicles around the University of Pennsylvania. Tidal flooding along the Delaware River also caused some moderate flooding in low lying areas on the river around 7 p.m. EDT.In Berks County, the effects of Floyd relatively speaking diminished. Nevertheless, numerous creeks and the Schuylkill River flooded. Many basements were flooded and numerous roads were closed into the morning of the 17th due to either standing water and/or debris. About 15 people were evacuated along the Allegheny (Robeson Township) and Sacony (Kutztown Borough) Creeks. Flooding along the Stony Creek forced the evacuation of a high school at 11 a.m. EDT. Flooding was also reported along the Hay and Monocacy Creeks. Water rescues were performed in Exeter and Longswamp Townships. About 31,500 homes and businesses lost power in the county due to downed trees and wires. Power was totally restored on the 20th. In the Lehigh Valley and the Poconos the winds of Floyd were as much of a problem as were the heavy rains. Numerous trees were knocked down. In Northampton County, there were over 100 calls for removal of downed trees. Downed trees closed U.S. Route 209 in Carbon County. GPU Energy reported 16,325 homes and businesses lost power in the Lehigh Valley and all power was restored on the 17th. PPL reported 41,000 homes and businesses lost power in their Eastern Pennsylvania service area. The heavy rain pushed numerous streams over bankfull. The Bushkill (Northampton County), Cedar (Lehigh County), Jordan (Lehigh County), Little Lehigh (Lehigh County), Monocacy (Lehigh County), Saucon (Lehigh County) and Trout (Monroe and Lehigh County) Creeks all flooded. Flooding and road closures were reported along U.S Route 22 and Pennsylvania State Routes 309,313,512 and 611. Numerous basements were flooded and several smaller roads were washed out. A mudslide closed Pennsylvania State Route 611 in the Delaware Water Gap National Recreational Area. The city of Allentown stopped drawing water from the Little Lehigh Creek because it was becoming contaminated with dirt and other substances. People were rescued from trapped cars in both Lower Macungie (Lehigh County) and Lower Saucon (Northampton County) Townships. Along the Schuylkill River in Berne (Berks County) it crested at 13.3 feet at Midnight EDT on the 17th. Flood stage is 12 feet. In Reading, it crested at 14.9 feet at 6 a.m. EDT on the 17th. Flood stage is 13 feet. In Montgomery County, in Pottstown, the Schuylkill crested at 14.4 feet at 4 a.m. EDT on the 17th. Flood stage is 13 feet. In Norristown, it crested at 22.1 feet at 3 a..m. EDT on the 17th, flood stage is 17 feet. In Philadelphia it crested at 14.1 feet at 4 a.m. EDT on the 17th. Flood stage is 11 feet. In Bucks County, the Neshaminy Creek at Langhorne crested at 21.9 feet, the second highest crest in history (Record set with Connie/Diane August 1955.). Flood stage is 9 feet. In Montgomery County, the Perkiomen Creek at Graterford crested at 16.6 feet at 9 p.m. EDT on the 16th. Flood stage is 11 feet. The East Branch of the Perkiomen Creek near Schwenksville crested at a RECORD BREAKING 14.2 feet. Flood stage is estimated at 7 feet. In Chester County, the West Branch of the Brandywine Creek in Coatesville crested at 8 feet at 9 p.m. EDT on the 16th. Flood stage is estimated at 7 feet. Farther downstream in Modena, it crested at 9.8 feet at 6 p.m. EDT on the 16th. Flood stage is 9 feet. In Downingtown, the East Branch of the Brandywine Creek crested at a RECORD BREAKING 14.7 feet at 8 p.m. EDT on the 16th. Flood stage is 7 feet. In Chadds Ford, the Brandywine Creek crested at a RECORD BREAKING 17.2 feet at 1a.m. EDT on the 17th. Flood stage is 9 feet. Both Brandywine Creek previous records occurred during Hurricane Agnes in June of 1972. The Valley Creek in Valley Forge crested at a RECORD BREAKING 14.5 at 5 p.m. EDT on the 16th. Flood stage is estimated at 7 feet. In Delaware County, The Chester Creek in Chester crested at 19.6 feet at 6 p.m. EDT on the 16th, second highest crest on record. Flood stage is 8 feet. In Philadelphia, the Wissahickon Creek near its mouth crested at a RECORD BREAKING 10.7 feet at 945 p.m. EDT on the 16th. Several smaller streams in Southeast Pennsylvania also had RECORD BREAKING crests. They included the Tohickon Creek near Pipersville (Bucks County) at 11.8 feet, the North Branch of the Neshaminy Creek at both New Britain (Bucks County) at 4.9 feet and Chalfont (Bucks County) at 11.4 feet, the East Branch of the Perkiomen Creek near Dublin (Bucks County) at 8.6 feet, Crum Creek near Newtown Square (Delaware County) at 11.9 feet, Ridley Creek at Media (Delaware County) at 15.0 feet and the Red Clay Creek near Kennett Square (Chester County) at 10.0 feet. Along the Delaware River itself in Philadelphia (near Washington Street), high tide crested at 9.4 feet above mean lower low water at 640 p.m. EDT on the 16th. Moderate tidal flooding along the river starts at 9.2 feet above mean lower low water. Precipitation storm totals (done from north to south with up to the four highest reported amounts per county) included: In Carbon County 7.24 inches at the County Tower, 6.95 inches in Lehighton, 6.55 inches in Beltzville and 6.12 at the F.E. Walter Dam. In Monroe County 8.01 inches in Bossardsville, 7.24 inches in Tobyhanna, 7.12 inches in East Stroudsburg and 6.50 inches in Pocono Summit. In Northampton County 9.99 inches in Bethlehem, 6.20 inches in Walnutport and 6.02 inches in Bath. In Lehigh County 7.62 inches in Allentown, 7.61 inches at the Lehigh Valley International Airport and 7.51 inches in Claussville. In Berks County 7.18 inches in Bechtelsville, 6.90 inches in Reading, 6.28 inches in Blue Marsh and 6.10 inches in Hamburg. In Bucks County 10.07 inches in Doylestown, 9.07 inches in New Hope, 8.85 inches in Furlong and 8.08 inches in Sellersville. In Montgomery County 11.26 inches in Norristown, 10.83 inches in Horsham, 9.65 inches in Bala-Cynwyd and 9.40 inches in West Conshohocken. In Chester County 10.31 inches in Phoenixville, 10.04 inches in Valley Forge and Chester Springs, 8.82 inches in Exton and 8.31 inches in Coatesville. In Delaware County, 12.13 inches in Marcus Hook, 10.64 inches in Newtown Square, 9.56 inches in Ridley Park and 8.25 inches in Chadds Ford. In Philadelphia, 8.12 inches at the Franklin Institute, 8.09 inches at Temple University, 7.11 inches at Fairmount Park and 6.77 inches at the Philadelphia International Airport. Peak wind gusts included 58 mph the Commodore Barry Bridge (Delaware County), 55 mph in Meckesville (Carbon County), 48 mph at the Philadelphia International Airport, 44 mph at the Reading Regional Airport and 43 mph at the Lehigh Valley International Airport. Another unwanted side effect from Floyd was extra mosquitoes.

Source: NOAA Storm Events Database, event_id 5722750. Narrative written by the NWS forecast office that issued the report.