Five victims of the Bucks County flooding are identified, as the search for 2 children goes on

Flooding downpours were all but inevitable, forecasters were warning during a weekend so steamy that it seemed that the saturated atmosphere itself was breaking out in a sweat.

However, no one foresaw the deluge that took the lives of at least five people in one of the region’s deadliest weather events on record. The intensive search continued Monday for 2-year-old Matilda Sheils, and her 9-month-old brother, Conrad. Their mother Katheryn Seley, 32, was one of three victims whose bodies were found Saturday.

Upper Makefield Township, not far from where George Washington and Continental Army soldiers famously crossed the Delaware River on a stormy Christmas night in 1776, has been historically flood-prone, but local residents said they never had witnessed rains of such ferocity as those of Saturday afternoon and evening.

» READ MORE: Bucks County flooding showed the ‘violent forces of nature’

Post-storm analysis will take some time, but a warming climate and recent ultra-warm Atlantic sea-surface temperatures may have been significant contributors, said Nicole Lobiondo, a Montgomery County native who is a meteorologist with AccuWeather in State College.

Said Upper Makefield Township Manager David Nyman, “I’ve experienced flooding along the Delaware, but nothing like this.”

In this instance, the Delaware evidently was a nonfactor: The deadly flooding occurred about a mile to the west along the narrow Hough’s Creek, a tributary of the river. The creek’s lack of width likely was a major player in the disaster. Narrow streams are way more likely to slosh over than wider bodies of water like the Delaware, said Seann Reed, hydrologist with the government’s Middle Atlantic River Forecast Center.

To that point, the Delaware at nearby Trenton jumped only about a foot, from just under 11 feet to 12, according to the National Weather Service.

The creek simply couldn’t hold the incredible volume of water falling from the sky and running off from paved surfaces in a compressed period. The nearest official gauge, in the middle of the Route 532 bridge at Washington Crossing, measured 4.64 inches, but one resident said he caught over nine inches in his bucket, said Nyman.

The creek came roaring out of its banks suddenly and dangerously.

“You don’t really think of these little creeks becoming so dangerous,” said Brittany Breen, whose photography studio is near the scene of the tragedy. She said she now will view those flood warnings differently. “You don’t really know what could flood.”

» READ MORE: An even deadlier flood occurred in Chester in 1971

FEMA recently commended Upper Makefield for flood-mitigation projects, including work on the creek, and announced that residents would be eligible for decreases in federal flood-insurance premiums.

But Nyman said that no one in Upper Makefield or anywhere else could have prepared for a flood of this magnitude.

“It will be interesting reviewing this impacts of this event and seeing if there is anything we could have done differently,” he said.

The entire region, most of eastern Pennsylvania, and all of New Jersey were under weather service flood watches — for Sunday, not Saturday, although the forecasts said Saturday showers were possible.

During the day Saturday, some parts of the region were hit with those random thunderstorms that have become a staple around here as the atmosphere has been locked in a pattern that has baked the Southwest with record heat and directed storm-producing disturbances toward the Northeast.

Late in the day, one of those storms began pounding Bucks and Mercer County, across the river, and as so often happens in summer ― especially this one — it stalled in place.

The weather service posted a flash flood warning at 5:18 p.m. for the area, noting that 2 to 3 inches of rain already had fallen. The rain may have received a boost from winds from the southeast bearing warm, moist air off the Atlantic, where sea-surface temperatures have been running several degrees above normal, said Lobiondo, the AccuWeather meteorologist, who used to live along the flood-prone Perkiomen Creek in Montgomery County.

“That’s something we’ve been concerned about,” said Lobiondo.

The victims evidently were swept away around 5:30, said Tim Brewer, the Upper Makefield fire chief.

All five of the known dead had drowned, said Bucks County Coroner Meredith Buck.

Three of the victims identified Monday — Enzo Depiero, 78, of Newtown Township; Susan Barnhart, 53, of Titusville, N.J.; and Katheryn Seley, a 32-year-old from Charleston, S.C. — were found Saturday. The children’s father survived.

The bodies of Yuko Love, 64, who also had suffered multiple injuries, and Linda Depiero, 74, both of Newtown Township, were recovered Sunday.

Rescue workers from both Pennsylvania and New Jersey are to join the search for the missing children on Tuesday.

“It is a sad time for these families, this community, and all of Bucks County as all efforts are focused on finding the missing children,” said Buck.

“This is a mass-casualty incident the likes of which we have not seen before,” the Upper Makefield Township Police Department said in a Facebook post.

Maya K. von Rossum, head of the Delaware Riverkeeper Network, an environmental group, said Saturday’s flooding was a clear symptom of a warming world — warmer air can hold more moisture, and that Pennsylvania’s and other officials need to start “taking the climate crisis seriously.”

» READ MORE: More extreme rains likely in our future

She added, “This is a horrifyingly sad catastrophe.”

AccuWeather’s Lobiondo said that while a downpour is a staple of summer, “it is happening more frequently.”

The atmosphere, she said, has been behaving differently in a warmer, moister environment.

The weather on Tuesday should be favorable for the continuation of the search, although the forecast does call for an outside chance of late-afternoon showers.

Inquirer staff writers Nick Vadala, Robert Moran, and Rob Tornoe contributed to this article.