Remnants of Hurricane Melanie had dropped more than 7 inches of rain on parts of Western Pennsylvania, raising the region's rivers past flood stage. Now, less than two weeks later, remnants of Hurricane Nakita stalled over the area, dumping more than a foot of rain in a period of about four days.
Forecasts called for the biggest flood in Downtown in more than 80 years, threatening hundreds of businesses on the North Side and Downtown.
It was a fictional scenario.
But it's one that feels increasingly possible in Western Pennsylvania on the heels of Hurricane Helene's cataclysmic inland flooding in southern Appalachia last fall.
Officials from local, state and federal agencies gathered Downtown last week at the U.S. Army Corps of Engineers Pittsburgh District headquarters. The Post-Gazette got exclusive access to the disaster-planning exercise, during which emergency management officials simulated how they'd respond to something far more catastrophic than anything they've grappled with in Western Pennsylvania.
"You really had a worst-case scenario here," said a representative from the Pennsylvania Emergency Management Agency.
"That's what we were going for," responded Julie D'Annunzio, an Army Corps emergency management specialist who ran the exercise.
Yet part of what prompted the six-hour training was that very real worst-case scenario that hit Southern states just a few months ago.
Helene ripped through the Southeast in September, killing more than 200 people and flattening entire towns hundreds of miles north of where the storm made landfall as a Category 4 hurricane in Florida. Well over a foot of rain fell in a matter of days across parts of western North Carolina, turning creeks into raging rivers that crashed down mountainsides. It was the deadliest U.S. hurricane since Katrina in 2005.
"People need to look at that and say, 'That could happen here,'" said Matt Brown, Allegheny County's chief of emergency services.
A report compiled by the First Street Foundation, a nonprofit whose climate change and flooding studies are used to inform emergency preparedness for government agencies, showed 12% of properties in the city of Pittsburgh would take on water in a 100-year flood. In simpler terms, areas in a 100-year floodplain have a 1 in 100 chance of suffering a flood in any given year.
That percentage is the ninth highest nationally in First Street's data, putting Pittsburgh among the likes of coastal cities such as Houston, Los Angeles and Virginia Beach.
Helene's rainfall led to a 1,000-year flood — one that had a 1 in 1,000 chance of striking the areas it upended in any given year. The unprecedented event spurred last week's disaster-planning exercise in Pittsburgh.
"Hurricane Helene hit so close to home," Ms. D'Annunzio said. "It opened everybody's eyes up."
Pittsburgh's biggest risk
Pittsburghers won't be displaced by rising sea levels.
But Western Pennsylvania is hardly immune from the effects of changes in climate worldwide that have seen ocean temperatures rise and other shifts from past patterns.
"It's extremes getting more extreme," said Alicia Miller, a hydrologist with the National Weather Service in Moon.
For Pittsburgh, that manifests as more extreme precipitation events — when inches of rain fall in a matter of hours, overwhelming some of the area's stormwater management infrastructure and increasing the risk of flooding.
Chief Brown called flooding Allegheny County's "No. 1" risk.
During last week's exercise, officials from six Western Pennsylvania counties, the City of Pittsburgh, the National Weather Service, the Army Corps and other agencies mapped out — literally and figuratively — how they can prepare for a Helene-like flooding event.
The Army Corps couldn't concretely answer some of the questions participants raised. The city and county offered vague responses to parts of the scenario — largely because participants had never experienced flooding remotely close to what was presented. But opening the conversation was a first step to preparing for the unprecedented.
"That's critical so that we're tightly tied together," said Col. Nicholas Melin, commander of the Army Corps' Pittsburgh district. "Because when we experience a high water situation or a rain event that's significant, you don't have a lot of time to make friends."
The Army Corps' role
Col. Melin leads a team of about 800, the vast majority civilians. Their mission is to reduce flood risk and maintain more than 300 miles of navigable rivers in the region.
The district maintains 16 flood control reservoirs, which Col. Melin described as a "high density" of federally managed dams.
The district — primarily comprising Western Pennsylvania but including slices of eastern Ohio , western New York , and northern West Virginia and Maryland — is familiar with flooding.
The Johnstown flood in 1889, which killed more than 2,000, remains Pennsylvania's — and one of the nation's — deadliest disasters.
Pittsburgh suffered its worst flooding in the St. Patrick's Day flood in March 1936, when a surge of melting snow swelled the Ohio River to 46 feet in Downtown — about 30 feet above its normal level and 15 feet higher than the flooding caused by the remnants of Hurricane Ivan in 2004.
The 1936 flood killed more than 60 people, left large swaths of Downtown submerged and caused, by some estimates, nearly $200 million in damage — the equivalent of more than $4 billion today.
If Pittsburgh were to get a Helene-level rainfall event today, "it could very well look like the '36 flood," Ms. Miller said.
But the region is far more prepared than it was in 1936.
After that disaster, the Army Corps constructed flood control reservoirs throughout the region that can capture water before it ever reaches the rivers that would flood the city. Without the reservoirs — the last was completed in 1990 — the crest during Ivan's 2004 flooding would have been 7.7 feet higher in Downtown, likely saving millions of dollars in flood damage, Army Corps records showed.
In a more recent example, the crest in the April 2024 flooding Downtown would have been nearly 6 feet higher without the reservoirs, according to those estimates.
Mitigation measures
At the Conemaugh Dam, which straddles Westmoreland and Indiana counties near Saltsburg, water surrounding the nearly 150-foot-high structure was largely calm, lapping against the concrete far below the dam's crest, when the Post-Gazette toured the site with the Army Corps in November.
About six months earlier, during the April flooding, the water behind the dam rose 52 feet in less than two days. The Army Corps opened the seldom-used crest gates to allow the overflowing Conemaugh River to jet through the dam once areas downstream had receded enough to handle the increased volume.
The Army Corps also works on other flood control projects, such as building concrete channels in Johnstown.
The agency estimates its reservoirs have prevented more than $15.2 billion in flood damage and its flood control projects have saved more than $2.7 billion through fiscal year 2024.
The decades of investment in flood mitigation — some stemming from the need to protect steel production along Western Pennsylvania rivers during World War II — provide the Pittsburgh area a layer of protection it lacked in 1936.
But that layer can only do so much. Col. Melin said Army Corps reservoirs capture only about a quarter of the watershed in the greater Pittsburgh region.
"We can reduce flood risk," he said. "We can never completely erase flood risk."
'Worst-case scenario'
The Army Corps goes through its own flood exercise every year. But in last week's session, the agency included external partners — partially in response to the sheer scale of Helene's destruction.
"We just went through flooding in April and that was well within our comfort level of our protocols and our procedures," said Ms. D'Annunzio , the Army Corps emergency management specialist. "So seeing something that was to [Helene's level] and ultimately resulting in federal declarations and FEMA response, we don't normally deal with that in Pennsylvania."
The flooding in fictional hurricanes Melanie and Nakita far exceeded any of the participants' comfort levels.
Adam Ameel, Pittsburgh's critical infrastructure manager, said the city would need to perform "a lot of life safety" at the peak of the flooding and tap into Allegheny County resources — including swiftwater rescue teams.
"In these major events, the jurisdictional boundaries go away," said Alan Hausman, an emergency management planner for the city.
One representative from PEMA said the flooding presented by the fictional hurricanes — a 36-foot crest at the confluence of the three rivers in Downtown — would be "a monster to manage."
That crest would be the fourth-highest in the city's recorded history. Hundreds of businesses in Downtown and the North Side would suffer serious flood damage, according to National Water Prediction Service models.
Water would rise to the top of the flood wall outside right field at PNC Park and would be on the verge of rushing into the floor level of Rivers Casino, according to the models.
Towns lining the region's rivers — and even those along normally shallow, trickling streams and creeks — could face still greater destruction.
"We were actually dealing with multiple scenarios that were escalating [during the exercise]," said Chief Brown of Allegheny County's emergency services. "Started with stream and creek flooding, and flash flooding eventually led to river flooding.
"The flash flooding is very difficult to plan for. Sometimes it just pops up."
Participants wrestled with how they'd manage recovery and cleanup operations after such a flood — efforts that remain ongoing in areas struck by Helene.
"Reading some of what was coming out of [ North Carolina ] was a little overwhelming," Ms. Miller, the hydrologist at the NWS Pittsburgh office, said a few weeks after Helene struck, while emergency officials were still searching for bodies.
Participants in last week's disaster-planning exercise didn't have one central takeaway from the hourslong gathering, other than to say they gained a better understanding of just how massive the coordinated response to a Helene-like event would be here.
They will continue to meet to hone their response plans and mutual aid needs. Many relationships already exist, particularly through a task force that brings together 14 Western Pennsylvania counties and the City of Pittsburgh regularly.
And much like they do when tornadoes strike, NWS experts also try to survey flood-damaged locations after the event to gain a better understanding of the circumstances to inform future needs.
Ms. Miller said NWS employees from the Pittsburgh office who responded when Johnstown flooded again in 1977, killing dozens of people, saw scenes that "stick with them for the rest of their lives."
Spring flooding outlook
The exercise came at the start of Pittsburgh's traditional flood season. Three of the city's five highest river crests have been recorded in March.
This spring does not seem to have the ingredients for a major flood — at least not yet.
The chance of a minor flood — an Ohio River crest of 22 feet in Downtown — hitting Pittsburgh dropped from 50% at the start of February to 20%, Ms. Miller said, right about average for this time of year.
The area is once again below average for snowfall through early March, meaning the threat of a snowmelt-induced flood like 1936 is small.
But there was even less snow a year ago, and flooding still struck in April.
"Even all the way up to the Army Corps, [we] have limited ability to stop or redirect the flow of that water. It's coming," Chief Brown said. "If we're not planning and preparing for it, shame on us."
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