Philadelphia local news, sports, jobs, cars, homes

Category: Science

  • Ice is building on Philly’s waterways as the snowpack persists and the cold intensifies

    Ice is building on Philly’s waterways as the snowpack persists and the cold intensifies

    Accompanying one of the more-enduring snowpacks in the period of record, ice has continued to build in the Philadelphia region’s waterways, and all indications are that it’s going to intensify in the next three days, perhaps significantly.

    With temperatures expected to fall to single digits by Saturday night and wind gusts up to 55 mph, the region is about to experience an assault from a “cold air gun,“ said Alex Sosnowski, senior meteorologist at AccuWeather Inc.

    The combination, plus the below-freezing temperatures at least through Monday and the ongoing cold spell that began last month, will not only deepen the ice cover but will make it more uniform by freezing over breaks in the ice.

    “You’re going to see the ice-over become more extensive,” Sosnowski said.

    Earlier in the week, icing temporarily stranded a vessel on the Delaware River that was delivering much-needed salt supplies to Philly. (They did eventually get here.)

    The U.S. Coast Guard was using a 175-foot-long cutter to break up ice on a portion of the river channel that runs from the mouth of the ice-covered Delaware Bay — where Cape May-Lewes Ferry service was disrupted this week — to Trenton.

    As of Friday morning, the craft had been ramming ice for 45 hours since the freeze began at the end of last month, U.S. Coast Guard Petty Officer Matthew West said.

    So far, however, the ice hasn’t reached crisis levels, said Ryan Mulvey, a spokesperson for the Philadelphia Regional Port Authority. For ship traffic on the river, it’s been more a matter of “road work ahead” rather than ”road closed.”

    “We’re open as usual,” he said. “I think the largest ships help with breaking up some of the ice flow.”

    One thing is certain, meteorologists are warning: The ice factory is going to be in full production mode until Tuesday.

    And, ironically, even as precipitation deficits and drought conditions persist, flooding potential is a source of concern.

    The short-term outlook for icing in the Philly region

    A key to melting, said Sosnowski, is having a sequence of daily average temperatures above freezing, not just daytime highs above 32 degrees. Nights also have to warm up.

    The prospects of that happening aren’t looking good for the next several days. Officially, Friday was the 12th consecutive day of a snowpack of at least 5 inches at Philadelphia International Airport, the seventh-longest such stretch in records dating to the winter of 1884-85.

    Daily average temperatures have been below freezing every day since Jan. 23.

    Highs on Saturday and Sunday, even in the city, may struggle to reach 20 degrees, with lows in single digits Sunday and Monday mornings.

    A promised warmup during the workweek wasn’t looking as toasty on Friday as it was earlier in the week. Monday’s temperatures were forecast to top out in the 20s, and no daily average temperatures are forecast above freezing through Friday.

    Some rain or snow also is possible Wednesday, said Nick Guzzo, a meteorologist with the National Weather Service in Mount Holly. A storm is possible next weekend, but computer models continue to disagree with each other, and themselves.

    To erase the snowpack, the region could use a warm, moist air mass and rain that would produce “river rises” that would help break up the ice, the weather service says.

    But not too much rain.

    The long-term outlook: Flooding concerns amid a drought

    Some of the worst flooding on record has resulted from ice-jamming, a signature example occurring after Philadelphia’s mammoth 1996 snowstorm.

    Moist air preceding a rainfall all but erased the snowpack with a historic melt. When that air came in contact with the snow, it condensed, releasing latent heat that sped up the melting.

    Rain followed, and liberated ice jams led to destructive flooding along the Delaware and the Susquehanna Rivers and a presidential disaster declaration.

    NOAA’s Middle Atlantic River Forecast Center is well aware of the potential and is monitoring conditions, said senior hydrologist Johnathan Kirk.

    “That’s what we have to watch for,” said Sosnowski, who well remembers 1996.

    “It is going to take one of the more mild-mannered thaws to avoid ice-jam flooding,” he said.

    A mild thaw is possible, Sosnowski said, but “the odds are stacked against it. It’s been so cold for so long.”

  • A dash of snow, an Arctic chill, and 55 mph wind gusts are possible this weekend in Philly

    A dash of snow, an Arctic chill, and 55 mph wind gusts are possible this weekend in Philly

    By now Arctic air may qualify for a frequent-visitor pass around here, but the version coming this weekend will be of a different quality and have a particular sting.

    “It’s going to be a slap in the face,” said Cody Snell, a meteorologist with the National Oceanic and Atmospheric Administration’s Weather Prediction Center.

    After a day in which highs will be around freezing on Friday — a solid 10 degrees below normal — some nuisance snow is possible late in the day or evening and early Saturday, and maybe even squalls. Then temperatures are going to tumble through the teens in the wake of another potent Arctic front.

    They might not see 20 degrees in the Philly region until Monday.

    Adding bite will be winds that could gust to 55 mph, and the National Weather Service says wind chills of 10 and 15 below are likely Saturday in the immediate Philly area. The agency has issued an “extreme-cold warning” — a relatively new addition to the advisory list — in effect Saturday afternoon through Sunday morning. Wind chills of 17 below zero are possible, and winds could gust to 55 mph, the weather service says.

    Said Ray Martin, a lead meteorologist at the weather service office in Mount Holly, “It’s going to be awful.” Among the recent sequence of Arctic invasions, “it looks like the worst.”

    In short, that unusually tenacious snowpack that was left over from the 9.3 inches of snow and white ice that fell on Jan. 25 and has since mutated into a form of frozen slurry will be spending at least another weekend in Philly.

    What’s more, it’s likely to be a harvest weekend for the ice that is solidifying upon the region’s waterways, a growing concern.

    A warm-up is due to begin Monday and pick up steam during the workweek, with highs maybe reaching 40 degrees on Thursday. But it may encounter some resistance, and another storm threat might be brewing for next weekend, forecasters say.

    The snowpack already has achieved an elite status

    Friday marked the 12h consecutive day in which the official snow cover at Philadelphia International Airport, measured daily at 7 a.m., was at least 5 inches.

    In the 142-year period of record, that ties for seventh place for a snow-cover duration of that depth.

    “To hold on to a snowpack like this is unusual,” said Johnathan Kirk, senior hydrologist at NOAA’s Middle Atlantic River Forecast Center, in State College, Pa., which is keeping a close eye on the waterway icing.

    The Schuylkill in Philly is ice-covered, as is the Delaware River from Trenton to Washington Crossing.

    In addition to an eight-day stretch when temperatures failed to reach 30, the durability is related to the 2 or so inches of sleet that capped the snow on Jan. 25. Sleet is white ice that melts more slowly than snow.

    The dry and cold air has been a natural preservative; snow and ice melt more readily when the air is moist.

    Another factor was the impressive liquid content of the snow and sleet, Snell said. The frozen mass contained 1.39 inches of liquid, the weather service said, comparable to what is contained in 15 to 18 inches of snow.

    As temperatures finally nudged above freezing, some melting did occur this week, which would explain that unsightly slushy porridge at Philly intersections. However, the official snow depth lost only an inch between Jan. 27 and Wednesday.

    The snowpack may receive a fresh frosting Friday night into early Saturday with up to an inch of snow, Martin said, but it’s not going to have the same staying power.

    What’s different about this Arctic air mass

    Any snow that falls is likely to get blown away in a hurry, Martin said, as winds will pick up before daybreak Saturday and gusts howl to 50 mph by late morning.

    Typically, cold air pours into the region from the northwest and becomes modified as it passes over land, the Great Lakes, and the mountains.

    This is going to be a straight-up Arctic shot. It will come more or less from the north, and the icy lakes are not going to do much to impede it, said Matt Benz, senior meteorologist at AccuWeather Inc.

    The weather center’s Snell said a weak storm system moving off the Atlantic coast is forecast to blow up as it interacts with warm Gulf Stream waters. The differences between the cold high pressure with its heavier air over the East and the lighter air of the storm are going to place the Philadelphia region in a frigid sandwich.

    Heavier air tends to rush toward lighter air, like air escaping from a punctured tire.

    A thaw is coming to Philly, eventually

    Just how warm it gets next week remains unclear, AccuWeather’s Benz said.

    “Arctic air is hard to dislodge sometimes,” he said, adding that recent model trends suggest the warm-up will not be quite as robust as expected earlier.

    A wild card would be a potential storm next weekend. The European forecast model was seeing rain and 60 degrees, Martin said, while the U.S. model was suggesting a blizzard.

    His take: “I have no clue at this point.”

    An anniversary of note

    On Feb. 5, 2010, 6.6 inches of snow fell upon the airport, the beginning of an unprecedented siege in which 44.3 inches accumulated in a six-day period.

    A man shovels cars out under mountains of snow in West Bradford Township, Chester County, during the incredible snow siege of February 2010.

    Twelve days after the snow stopped, the official snow depth was down to 4 inches.

  • $29M in federal and private funds to go toward Delaware River watershed projects

    $29M in federal and private funds to go toward Delaware River watershed projects

    Federal and private grants totaling nearly $29 million were announced Wednesday for conservation projects within the Delaware River Watershed, including a South Philadelphia wetlands park, a water trail in Camden County, and support of the Lights Out Philly program to keep birds from crashing into buildings.

    The money comes from nearly $12.5 million in grants to the Delaware Watershed Conservation Fund from the National Fish and Wildlife Foundation (NFWF) and the U.S. Fish and Wildlife Service. An additional $17 million comes in matching funds from nonprofits such as the Philadelphia-based William Penn Foundation.

    The total is about $9 million less than last year’s grant awards of $38 million. A representative for the two federal agencies did not state a reason for the decline.

    However, the reduction comes as many federal grants have been cut or reduced by President Donald Trump’s administration.

    What’s being funded?

    In all, the new funds will flow to 30 conservation projects, including local trail creations, stream restorations, shoreline enhancements, and wildlife habitat improvements. The money will go toward planning, hiring for, and construction of projects in Pennsylvania, New Jersey, Delaware, and New York.

    Jeff Trandahl, executive director and CEO of NFWF, said the projects “demonstrate the impact that public-private partnerships can have at a landscape scale and will help ensure a healthier and cleaner future for the Delaware River watershed and the communities and species that depend on it.”

    The watershed is within a densely populated corridor but remains 50% forested. Four hundred miles of it is classified as a National Wild and Scenic River, largely undeveloped but accessible for recreation.

    The grants cover a wide range of projects.

    For example, $498,800 will go toward reducing migratory bird collisions into buildings throughout the Delaware Watershed, which includes Philadelphia and New Jersey. The project of the Wildlife Management Institute, along with Bird Safe Philly, will identify and retrofit buildings to be bird-friendly, inform the public about built-environment hazards, and how to mitigate them.

    Leigh Altadonna, coordinator for Bird Safe Philly, a collaborative of five organizations, welcomed the grant.

    “These funds will reinforce Bird Safe Philly’s continuing work with nature centers, libraries, arboretums and other buildings as part of our mission to mitigate bird collisions with glass,” Altadonna said.

    She said money would go toward educating the public about how to make their homes and communities bird-friendly.

    Bird Safe Philly coordinates with owners of the city’s skyscrapers to turn off or dim lights, which can attract birds during the spring and fall migration seasons.

    ‘The right thing to do’: How a darkened Philly skyline has helped save birds

    A sample of grants with total federal and private funding

    Pennsylvania

    • $650,000 for South Philadelphia Wetlands Park II, a project of the Delaware River Waterfront Corp. The money will go toward completing needed documentation for the park located just south of the base of Tasker Street through Pier 70. The goal is to restore wetland habitat and increase public access to piers and berths, add a kayak launch and a natural pier park, and restore two acres of forested upland, meadow and wetlands.
    • $2 million for stream channel restoration in the south branch of French Creek, a project of the French and Pickering Creeks Conservation Trust. The stream channel and surrounding wetland will be improved as a habitat for brook trout and bog turtle, restore 6.7 acres of riparian buffer, and more than 13 acres of surrounding wetland and flood plain.
    • $900,400 to reintroduce wild brook trout in restored agricultural watersheds in Chester County, a project of the Stroud Water Research Center, which will monitor the re-establishment effort and implement agricultural best management practices to give trout the best chance of recovery.

    New Jersey

    • $3.5 million for horseshoe crab and shorebird habitat at the Kimbles Beach and Bay Cove area in Cape May Court House, a project of the American Littoral Society. The money will go toward restoring one mile of critical habitat along the Delaware Bay, by placing 49,000 tons of sand to stabilize the beach, reverse coastal erosion, and protect the shoreline.
    • $1.2 million for restoration and recreational projects on the Cooper River Water Trail, which is spearheaded by the Upstream Alliance. The money will go toward engaging 3,000 community members through hands-on recreational programming, hiring local youth, and promoting public access on the new trail in Camden County. It will include paddling and fishing programs for the community and create a Friends of the Cooper River Water Trail group.
    • $487,400 for ecological restoration and wildlife habitat improvements at Swede Run Fields in Moorestown, Burlington County, for a project by the township to eradicate invasive species and establish native plant communities within the wetlands, riparian forest, and upland meadow buffers.
  • NASA delays astronauts’ lunar trip until March after hydrogen leaks mar fueling test

    NASA delays astronauts’ lunar trip until March after hydrogen leaks mar fueling test

    CAPE CANAVERAL, Fla. — NASA’s long-awaited moonshot with astronauts is off until at least March because of hydrogen fuel leaks that marred the dress rehearsal of its giant new rocket.

    It’s the same problem that delayed the Space Launch System rocket’s debut three years ago. That first test flight was grounded for months because of leaking hydrogen, which is highly flammable and dangerous.

    “Actually, this one caught us off guard,” NASA’s John Honeycutt said Tuesday, hours after the test came to an abrupt halt at Kennedy Space Center.

    Until the exasperating fuel leaks, the space agency had been targeting as soon as this weekend for humanity’s first trip to the moon in more than half a century.

    “When you’re dealing with hydrogen, it’s a small molecule. It’s highly energetic and we like it for that reason and we do the best we can,” Honeycutt explained.

    Officials said the month-long delay will allow the launch team to conduct another fueling test before committing the four astronauts — three U.S. and one Canadian — to a lunar fly-around. It’s too soon to know when the countdown dress rehearsal might be repeated.

    Any repairs to deformed or damaged seals, or other components, can likely be completed at the pad, managers said. A return to the Vehicle Assembly Building would likely result in an even longer delay.

    The leaks cropped up early in Monday’s loading operation and again hours later, ultimately halting the countdown clocks at the five-minute mark. Launch controllers had wanted to get all the way down to a half-minute in the countdown, but the escaping hydrogen exceeded safety limits.

    NASA repeatedly interrupted the flow of liquid hydrogren, which was minus 423 degrees Fahrenheit, in an attempt to warm up the area between the rocket and fuel lines and, hopefully, reseat any loose seals. But that didn’t work and neither did altering the flow of the hydrogen — adjustments that allowed the first SLS rocket to finally soar without a crew in 2022.

    With their launch now off until at least March 6, commander Reid Wiseman and his crew were given the all-clear to emerge from quarantine in Houston. They will reenter it two weeks before the next launch attempt.

    Wiseman said on the social platform X that he was proud of how the dress rehearsal went, “especially knowing how challenging the scenario was for our launch team doing the dangerous and unforgiving work.”

    The extreme cold at the launch site did not contribute to the fuel leaks or any other problem, according to officials. Heaters kept the Orion capsule warm atop the 322-foot rocket, while constant purging protected the rocket and ground systems.

    Amit Kshatriya, NASA’s associate administrator, stressed that the Space Launch System is “an experimental vehicle,” with more lessons to be learned. Years between fueling tests and flights don’t help, he added.

    “I’m just reminded again almost four days and 40 years from Challenger, nobody sitting in one of these chairs needs to be calling any of these vehicles operational,” Kshatriya said at a news conference.

    NASA has only a handful of days any given month to send them around the moon — the first time astronauts will have flown there since 1972. They won’t land on the moon or even go into lunar orbit during the nearly 10-day mission, but rather check out life support and other vital capsule systems ahead of a moon landing by other astronauts in a few years.

    NASA sent 24 astronauts to the moon during the 1960s and 1970s Apollo. The new Artemis program is aiming for new territory — the moon’s south polar region — and looking to keep crews on the lunar surface for much longer periods.

  • It’s ‘Groundhog Day’ in Philly this week as snow and ice persist

    It’s ‘Groundhog Day’ in Philly this week as snow and ice persist

    If it appears that the tenacious meringue of snow and ice that landed on the region two weekends ago hasn’t budged, it hasn’t.

    Among Philadelphia winters, this one is approaching a rarefied status.

    Not long after Phil predictably saw his shadow in Punxsutawney, the National Weather Weather Service contractor at Philadelphia International Airport reported a snow depth of six inches on Monday.

    That marked the eighth consecutive day of a snow cover of at least six inches, a streak unmatched since February 2010 — which included a five-day period in which 44 inches of snow had fallen.

    And what’s out there now may get a fresh frosting on Tuesday night that could affect the Wednesday morning commute, and perhaps snow squalls on Friday with the approach of another Arctic front as the freezer reopens.

    Don’t be surprised if next Monday morning looks a lot like this one.

    “The snowpack is not going anywhere,” said Amanda Lee, meteorologist at the weather service office in Mount Holly.

    What explains the durability of the snow cover

    The primary factor locking in the regional glacier has been the obvious — the cold. Sunday marked the ninth consecutive day that temperatures failed to surpass freezing, the longest stretch since 2004. The temperature did reach above freezing at Philadelphia International Airport on Monday.

    Temperatures since Jan. 24 have averaged 14 degrees below normal in Philly. January temperatures ended up finishing 2.2 degrees below normal, even though the month had a nine-day warm spell in which the highs went past 55 on five days.

    In addition to the cold, the icy layers of sleet that have put a cap and a patent-leather sheen on the several inches of snow that fell Jan. 25, have limited melting. Ice is way slower to melt than snow.

    Eight days after an official 9.3 inches of snow and ice was measured officially, about two-thirds of it has survived.

    The forecast for the next several days

    The region is in for a modest — very modest — warming trend. Readings cracked freezing Monday, reaching 35 degrees at 4 p.m. and are forecast to top out near 32 on Tuesday and Wednesday, and hold in the upper 20s Thursday. Those readings still would be several degrees below normal.

    Some light snow is possible Tuesday night, “maybe up to an inch,” Lee said. The weather service on Monday was listing a 72% probability of something measurable — defined as 0.1 inches or more — falling in Philly.

    Given the cold and the solidly frozen paved surfaces, “it could make things slippery for the morning commute on Wednesday,” said Matt Benz, senior meteorologist with AccuWeather Inc.

    Friday afternoon, he said, the region could see snow squalls — brief, mini-blizzards that can come on without notice and reduce visibility dangerously.

    Then it’s back to the freezer with expected weekend lows in single digits and highs struggling to reach 20.

    For those ready for something completely different, NOAA’s Climate Prediction Center on Monday suggested the potential for significant pattern change, although this may require a little patience around here.

    Its extended outlook for the six-to-10 day period that begins Sunday has most of the nation warmer than normal, with odds strongly favoring below-normal readings in the Philadelphia-to-Boston corridor. But a “rapid warmup” in the Philly region is possible around mid-month, the climate center says.

    In the short term, it appears that Philly is in for a repetitive sequence evocative of the 1993 movie classic Groundhog Day.

    “We’ve had lots of very similar days,” Lee said.

    We’ve noticed.

  • The arctic cold persists, and so does Philly’s snowpack. Both may even go away some day.

    The arctic cold persists, and so does Philly’s snowpack. Both may even go away some day.

    It looks like the Philly region will evade any snow generated by that coastal “bomb cyclone” during the weekend, but the disruptive snowpack on the ground continues to melt at a glacial pace. Maybe ever slower.

    “For now, it’s not budging,” said David Robinson, the New Jersey state climatologist who is an international expert on snow cover.

    And, ironically, that has a whole lot to do with what happened in the hours right after the snow stopped around 11:30 a.m. Sunday.

    Add one of the more signifiant Arctic cold spells in Philadelphia’s period of record, and the entire region has endured a white and wintry week rarely experienced around here.

    As of Friday morning, the official snow depth at the airport still was 6 inches, about two-thirds of what was measured when the storm ended five days before.

    For perspective, the depth was 6 inches five days after a snowstorm in 2016 — after 22.4 inches had fallen.

    The cold won’t be as harsh during the workweek, but a thaw isn’t imminent, and some snow is possible Wednesday.

    Temperatures are forecast to drop deep into the single digits Saturday morning, flirting with records. It is not due to get into the 20s until Sunday, when backlash winds from the potent coastal storm are expected to drive wind chills below zero.

    Those winds may contribute to significant flooding at the Shore, where they could gust to 50 mph.

    About last Sunday in Philly

    About 7.5 inches of snow had fallen officially by 11:30 a.m. Sunday at Philadelphia International Airport, more in some other places, when it yielded to several hours of sleet that accumulated 2 to 3 inches, coating the snow with a sparkling, icy veneer.

    “You can’t help but recognize the beauty of it,” said Robinson, a Rutgers University geography professor and keeper of the Rutgers Snow Lab.

    While it may be an aesthetic pleasure, especially at night under the full “snow moon” rising this weekend, it has had a profoundly chilling effect on cleanup efforts.

    The sleet, liquid that freezes before it lands, literally put an ice cap on the snow. “Ice pellets are tougher to melt,” said PennDot’s Thomas Rogal, a maintenance supervisor for the Philadelphia district. In a melting race, a homely sleet ball wouldn’t have a chance against a six-sided snowflake.

    On Sunday, said Rogal, the sleet was a game-changer for the road crews. Instead of just plowing, crews were “scraping the road surfaces,” he said. Sleet added a stubborn stickiness to the mass of frozen material.

    It also contained about as much liquid as several inches of snow, said Robinson.

    The surprisingly cold temperatures, in the lower 20s and teens, inhibited the effectiveness of salt on Sunday. “The material just didn’t function,” said Rogal.

    In the city, the glacial mass has been especially disruptive, a royal, inconvenient pain for people living on side streets, for street crews, for anyone who has tried shoveling, and for the schools.

    In addition to the snow and ice challenges, the cold has stressed aging heating systems in the public schools, once they reopened.

    A thermometer in a Central High School classroom on Friday read 39 degrees. That’s colder than the normal high for the date in Philly — outdoors.

    When will all this go away?

    Philly hasn’t had a stretch of days like this in which the temperature has failed to reach 30 degrees since 1979, according to records tracked by the Pennsylvania state climatologist.

    And it likely is going to finish in the top 10 for consecutive days in which readings didn’t get past freezing, said Mike Silva, a meteorologist with the National Weather Service in Mount Holly.

    Low temperatures Thursday and Friday morning, 13 and 11, respectively, were several degrees above the forecasts. That probably was related to the winds at the airport, he said.

    It also may be related to the sleet, said Robinson: Ice doesn’t have quite the same chilling effect as fresh snow.

    Conditions Saturday morning — clear skies and lighter winds — should be more conducive for daytime heating (we use the term loosely) to radiate into space. Morning lows could approach the record of 3 degrees, set in 1948.

    Some moderation is expected with the workweek, but not much. “We were hoping to get to the mid-30s,” said Sliva, but “it looks like we may barely get to freezing.”

    Even at those temperatures, some melting should occur.

    The total daily solar energy beaming toward Philly now is about 30% higher than it was on Jan. 1, according to NASA’s calculations, and the sunrise-to-sunset time is increasing by about two minutes a day.

    Even the cold has a bright side, said PennDot’s Rogal. Potholes, it turns out, have something in common with a lot of humans: “They aren’t particularly fond of this weather.”

    “The freeze-thaw is what always gets us,” he said. “We’re actually in better shape when the cold sets and stays.”

    Even if it snows next week — “There’s a couple of systems that could affect us,” said Silva — based on 150 years of official record-keeping for Philly, it is going to warm up and the ground will reappear.

    Eventually.

  • A coastal ‘bomb’ and single-digit temperatures are expected this weekend in the Philly area

    A coastal ‘bomb’ and single-digit temperatures are expected this weekend in the Philly area

    It remains a long shot that a fresh layer of frosting will coat the hardening and tenacious snowpack, but evidently that street-congesting frozen mass isn’t exiting in the near future.

    As of Friday morning, it appeared that a potent coastal storm that is expected to qualify as a meteorological “bomb” was going to spare the Philadelphia region from another snowfall.

    But it is expected to have serious impacts on the New Jersey and Delaware beaches, with a combination of onshore gales and a tide-inciting full moon, forecasters are warning.

    On the mainland, it is poised to generate winds that would add sting to what has been one of the region’s most significant outbreaks of Arctic air in the period of record.

    Lows at Philadelphia International Airport both Thursday and Friday mornings — 13 and 11, respectively — were several degrees above what was forecast.

    But they are to drop into single digits Saturday morning, and flirt with a record. Wind chills during the weekend are expected be in the 10-below range, said Mike Silva, a meteorologist with the National Weather Service in Mount Holly.

    “Even though there might not be much or any snow in Philly,” he said, “it’s going to be cold, and we’re still going to have the wind impacts.”

    window.addEventListener(“message”,function(a){if(void 0!==a.data[“datawrapper-height”]){var e=document.querySelectorAll(“iframe”);for(var t in a.data[“datawrapper-height”])for(var r,i=0;r=e[i];i++)if(r.contentWindow===a.source){var d=a.data[“datawrapper-height”][t]+”px”;r.style.height=d}}});

    Is the snow threat off the table for Philly?

    Computer models continue to keep the storm far enough off the coast to preclude a major snowfall inland.

    But “it wouldn’t take much of a jog west to really mess up the forecast,” said Tom Kines, senior meteorologist with AccuWeather Inc. It’s been known to happen.

    On Friday morning, the National Weather Service was posting a 30% chance that Philly would get something measurable — technically 0.1 inches — Saturday night into Sunday, with about a 10%shot at an inch.

    The weather service was expecting an inch at the Shore, but with a slight chance of several inches.

    Forecasters are certain that a storm is going to blow up off the Southeast coast as frigid air that is penetrating all the way to Disney World interacts with the warm waters of the Gulf Stream.

    Gusts at the Shore during the day Sunday might be as high as 40 mph as the storm could reach “bomb” status.

    What exactly is a ‘bomb?’

    Two brave souls endure the snow and winds from a meteorological bomb cyclone in Atlantic City in January 2022.

    The technical definition of a meteorological bomb is a drop in central barometric pressure of 0.7 inches in a 24-hour period, about a 2% to 3% change in the weight of the air. That might not seem like much, but it’s a big deal if you’re a column of air.

    Such a drop in pressure indicates a rapidly developing storm. Air is lighter in the centers of storms, as precipitation is set off by lighter warm air rising over denser cold air.

    As a weather term, bomb first appeared in an academic paper in 1980 by atmospheric scientists Frederick Sanders at the Massachusetts Institute of Technology and John Gyakum at McGill University.

    They found that the western Atlantic, in the proximity of the Gulf Stream, was one of two regions on the planet most prone to bombs. The other was the area near the Kuroshio Current in the far northwestern Pacific.

    Both are massive reservoirs of warmer waters that interact with cold air coming off land masses. Some of the European settlers in the colonial era learned about the effects the hard way, experiencing mega-storms that were alien to areas in England.

    Gyakum, who was Sanders’ graduate student at MIT, recalled Thursday that the duo took some blowback for using the word bomb.

    But with a cyclone of such ferocity, the term was worth using to draw the public’s attention to potential impacts, which sometimes exceed those of hurricanes, Gyakum said.

    He said he had no doubt this weekend’s storm would reach bomb status.

    While any heavy snows from this storm are likely to bypass the Philly region, some accumulating snow is possible the middle of next week, Kines said, although nothing in a league with what happened Sunday.

    When can Philly expect a thaw?

    Temperatures during the coming workweek are due to moderate, at least slightly, with highs around freezing Monday through Thursday, 10 to 12 degrees warmer than what is expected this weekend.

    The cold “certainly eases up,” Kines said.

    But that 9.3 inches of snow and sleet that accumulated Sunday evidently has taken a particular liking to the region. As for when it will disappear, he said: “It’s going to take a while.”

    The overall cold upper-air pattern looks to persist, said Paul Pastelok, AccuWeather’s long-range forecaster. And the extensive snow cover is going to have a refrigerant effect on temperatures.

    So when will it warm up and go away?

    “We’ll find out Monday,” Kines said. He was referring to Groundhog Day, of course, when Punxsutawney Phil will issue his extended forecast.

    Nevertheless, he said, meteorologists will be on call if needed.

    “It never hurts to get a second opinion,” he said.

  • Another weekend snow watch and ‘exceedingly rare’ cold are on tap for Philly

    Another weekend snow watch and ‘exceedingly rare’ cold are on tap for Philly

    Another weekend snow chance and more cold are in the forecasts. But the big difference between last week and this one in the Philadelphia region is a matter of degrees — about 10 of them.

    A coastal “bomb cyclone” could form during the weekend with significant impacts, at least at the Shore. Computers were still sorting out what effects, if any, it would have in Philly. On Thursday, however, they favored snow staying to the south and east, with only a 40% chance they got to I-95.

    In the meantime the cold will be epical by Philly standards.

    If the forecast holds, in addition to coming close to ending a 32-year zero-less streak, Philadelphia would have daily minimums of 5 degrees Fahrenheit or lower on the next two mornings.

    And it appears the city will have its first nine-day stretch in which the temperature failed to reach 30 degrees since 1979, based on analysis of temperature data from the Pennsylvania state climatologist.

    In issuing a cold weather advisory for wind chills as low as 10 below zero, the National Weather Service in Mount Holly noted that “it is exceedingly rare to get this combination of length and magnitude of an arctic airmass for this area.”

    Philadelphia’s forecast high on Thursday, 19, would be more than 10 degrees lower than the forecast for Anchorage, Alaska.

    Heading into the weekend, that subtly laminated lunar landscape with the one-horse-open-sleigh look in the fields and parks is almost certain to persist while bedeviling road-clearing efforts.

    Some snow is possible late Saturday or Sunday — and this is becoming a habit — in time for the rising of the full “Snow Moon,” which may be a problem for the Jersey Shore. The full moon will likely contribute to tidal flooding.

    Snow removal contractor Jordan Harlow clears the sidewalk in front of an apartment building on Main Street in Doylestown Wednesday, Jan. 28, 2026, following Sunday’s snowstorm. He said the layer of ice made it twice as difficult to use the snow blower.

    The snow outlook for the weekend

    On Wednesday only two things were certain about the latest threat: A major coastal storm is going to blow up during the weekend, and it’s not going to rain.

    “Everything looks like it’s going to come together,” said Paul Pastelok, the long-range forecaster for AccuWeather Inc.

    AccuWeather said it may intensify enough to qualify as a “bomb cyclone.”

    An early consensus among computer models was that the storm would stay too far offshore to generate a major snowfall in the immediate Philly area. Pastelok said it was looking for Philly to get “sideswiped” with a 1- to 3-inch event. However, that was very much subject to change.

    The weather service would not be making a first guess at potential accumulations until Thursday afternoon, said Alex Staarmann, a National Weather Service meteorologist in Mount Holly. In its forecast discussion Wednesday, it said that based on a consensus of the models, the Shore had a 35% to 50% chance of 6 inches of snow or more, with a 20% chance along I-95.

    More certain was the potential coastal flooding threat at the Shore with potent onshore winds coinciding with Sunday’s full moon.

    And while it may seem the atmosphere enjoys ruining weekends, it’s not uncommon for weather systems to fall into 3½- and seven-day cycles. That has to do with the spacing between weather systems, meteorologists say.

    Regardless of what happens during the weekend, the region is going to begin the workweek with snow on the ground.

    The snow is going to have more staying power than the average computer-model snow forecast.

    It’s not going to get a whole lot warmer anytime soon

    Even though it’s ice cold, as if developing a slow leak, the depth of the snow pack is actually decreasing, but ever so ponderously.

    That 9.3 inches of snow and sleet that accumulated Sunday was down to 6 inches at Philadelphia International Airport on Wednesday morning, Staarmann said.

    Compaction and sublimation, which is similar to evaporation, are lowering the depth, despite the cold. But Wednesday’s depth report was the same as Tuesday’s.

    Philly snow cleanup: What to know about plowing, parking, schools, and more

    And after what does or doesn’t happen Sunday, temperatures are forecast to remain below freezing at least until Feb. 4.

    No significant warm-up is in sight, and the National Oceanic and Atmospheric Administration’s Climate Prediction Center has odds strongly favoring below-normal temperatures until Feb. 11.

    The upper-air pattern continues to favor cold pouring into the Northeast.

    And more cold air is possible later in the month with a visit from the polar vortex, Pastelok said.

    Average temperatures in Philly finished 3.6 degrees below normal in December, and despite a 10-day warm spell earlier in the month, January is projected to finish at least 2 degrees below long-term averages.

    For Pastelok and other seasonal forecasters, it has been a tough winter.

    “We underestimated how cold the Northeast would be this year,” he said.

  • After Philly’s biggest snow in 10 years, a very big chill is coming

    After Philly’s biggest snow in 10 years, a very big chill is coming

    For the Philly region Monday it wasn’t so much a matter of digging out from the heftiest snowfall in a decade, it was more like a chipping, shaving, scraping, expletive-inducing, and ice-chunk hurling operation.

    Public transportation appeared to be getting back on track, and major roads were open for business with speed reductions removed, thanks to crews working through the weekend.

    But expect some side streets in the city and elsewhere to remain fit for sleigh rides this week and trash pickup to be delayed. City offices will be shut down again Tuesday, as will Philly school buildings, with Camden and more calling for a snow day or opting for remote learning.

    And if you’re stepping outside, get used to that underfoot crunching sensation. The removal operation isn’t going to get much help this week from the atmosphere. It’s about to turn about as frigid as it ever gets around here. New Jersey officials are warning of “historic” demands on energy.

    “We’re going to be in the freezer all week,” said Mike Gorse, meteorologist at the National Weather Service Office in Mount Holly. Philly may have its first zero-degree reading in 32 years later in the week.

    It’s as if after recent wimpy winters, the Arctic is reacquainting with Philly and much of the rest of the East.

    And did we mention another snow threat for the weekend?

    “There’s a chance,” said Marc Chenard, meteorologist with NOAA’s Weather Prediction Center in iced-over College Park, Md., who was among those who had to chuck some frozen boulders before leaving for work Monday morning. “I had to chip it and carry it in pieces,” he said. Sound familiar?

    Why this storm was particularly challenging

    Snow totals for the biggest snowfall since Jan. 22-23, 2016, varied throughout the region; the inconveniences, not so much.

    A general 8 to 12 inches of snow and sleet accumulated while temperatures remained mostly in the teens Sunday, 10 degrees or more below forecast.

    A shallow layer of warmer air caused a changeover to sleet, and the tiny ice balls remained frozen for the entire trip through the stubbornly cold air near the surface. As much as 2 to 3 inches of sleet piled on, containing the same amount of liquid as several inches of snow.

    That added weight to the snowpack. Based on the amount of melted precipitation measured in the 9.3 inches at Philadelphia International Airport, the snowpack weighed about as much as a 12- to 15-inch pile of the pure flaky fluff.

    On a 200-square-foot driveway — a 10 by 20 — what fell Sunday weighed about 1,100 pounds. On a 100-square-foot sidewalk — 5 by 20 — that would be about 550 pounds.

    In addition, ice tends to be rather shovel resistant.

    This is going to be a memorably cold week in Philly

    The ice and snow isn’t going to give up easily. On Monday, temperatures topped out in the upper 20s, and that’s going to be warmest day of the week.

    Based on the forecast, it may not get above 28 degrees until next week, said Chenard, a cold streak the region hasn’t seen in decades.

    Chenard said the upper-air patterns remain in place to import Arctic air on winds from the northwest for at least the next several days.

    In fact, temperatures may have trouble getting out of the teens in Philly until the weekend, and Philly has a shot at reaching zero for the first time in 32 years.

    The forecast lows are in the single digits all week, and down to 1 degree on Friday morning and 2 degrees on Saturday, the National Weather Service says. Both would be record lows for the dates.

    The stubborn snow cover “absolutely” will increase the chances of the airport reaching zero for the first time since January 1994, Gorse said. Snow is ideal for radiating daytime warmth (such as it is) into space.

    Temperatures will moderate some on the weekend, he said, but that might come in advance of yet another storm.

    Said Chenard, “There will be coastal low. It’s a matter of how close it is.”

    window.addEventListener(“message”,function(a){if(void 0!==a.data[“datawrapper-height”]){var e=document.querySelectorAll(“iframe”);for(var t in a.data[“datawrapper-height”])for(var r,i=0;r=e[i];i++)if(r.contentWindow===a.source){var d=a.data[“datawrapper-height”][t]+”px”;r.style.height=d}}});

    One historic footnote in the Philly weather annals

    Philly’s official snowfall total for the winter stands at 15.7 inches, almost double normal for the date and double what fell all of last season.

    Sunday’s was not only the biggest snow in 10 years, it also set a record for a Jan. 25.

    It beat the 8.5 inches of Jan. 25, 2000, a day that the weather service just as soon would like to forget.

    The storm came as a surprise, just a week after a weather service honcho announced a computer upgrade that would bring the nation closer to a “no surprise” era.

    Expect surprises to continue.

    Staff writers Ximena Conde, Kristen A. Graham, Maddie Hanna, Rob Tornoe, and Nick Vadala contributed to this article.

  • Heavy snow and potentially dangerous icing are expected in Philly this weekend

    Heavy snow and potentially dangerous icing are expected in Philly this weekend

    After the coldest morning of the winter, Philadelphia could experience more snow this weekend than it did during the entire winter of 2024-25, accompanied by a potentially nasty mix of ice.

    The National Weather Service on Saturday was holding serve on its call for 8 to 12 inches in and around Philly, and those amounts may be tweaked depending on the best guesses on how much sleet and freezing rain enters the mix. AccuWeather Inc. was going with 6 to 10.

    Subtle changes to accumulation forecasts are likely, but that merely would mean, “We’re just getting a different blend of horrors,” said Mike Lee, a meteorologist in the Mount Holly office.

    One thing is certain: Whatever falls won’t melt. Temperatures dropped into single digits throughout the region, and got as low as 11 at the Philadelphia International Airport banana belt. . Temperatures won’t get above the mid-20s while anything is falling from the skies Sunday and early Monday.

    The weather service has issued a profoundly predictable winter storm warning, in effect from 7 p.m. Saturday until 1 p.m. Monday.

    Whatever the outcome, the storm still in its formative stage already has had significant impacts on the region and may have set an unofficial record for pre-storm buildup and preemptive closings.

    Philadelphia Mayor Cherelle L. Parker declared a state of emergency for Sunday, as did Pennsylvania Gov. Josh Shapiro and New Jersey Gov. Mikie Sherrill. PennDot is imposing speed restrictions. SEPTA is expecting issues.

    Some schools already were planning for multiple-day closings, as the snow and ice will be accompanied by one of the region’s more impressive cold snaps of the last several years.

    Philadelphia schools will be closed Monday because of snow; others will likely follow

    Were it not for the storm, in fact, the cold might be getting headlines.

    Wind chills Saturday morning are expected to drop below zero. Sunday’s high of 25 degrees may make it the warmest day of the week.

    It is likely that layers of snow and ice will harden into a frozen mass that the January sun won’t be able to do a whole lot about.

    As a public service, for now we will hold off on mentioning another potential storm threat.

    The latest on the timing of the storm in Philly

    While the weather service warning goes into effect 7 p.m. Saturday, flake sightings could hold off until daybreak Sunday, said Alex Staarmann, a weather service meteorologist.

    Snow may accumulate rapidly Sunday morning with temperatures in the teens. Models were suggesting sleet could mix in as soon as early afternoon, said Tom Kines, senior meteorologist with AccuWeather Inc.

    Temperatures in the bottom 5,500 feet of the atmosphere are going to remain well below freezing. However, as the coastal storm intensifies, its onshore winds from the northeast are forecast to import warmer air from over the ocean into the upper atmosphere, which would change the snow to sleet and rain.

    It’s possible the precipitation will flip back to all snow and accumulate maybe another inch early Monday, Staarmann said. But at that point it would have all the impact of drizzle in the ocean. The mass of snow and ice evidently will be vacationing in Philly for a while.

    “It will stick around for a week, maybe two weeks,” Staarmann said.

    How much for Philly?

    Just how much snow and ice would be on the ground remained unclear Friday. And it’s all but certain the projections are going to change. For the record, a grand total of 8.1 inches fell all of last season in Philly.

    Louis Uccellini, former head of the National Weather Service and one of the nation’s most prominent winter-storm experts, said some later modeling was cutting back on the ice in areas west of the city, suggesting the possibility of higher snow amounts.

    (function () {window.addEventListener(‘message’, function (e) { var message = e.data; var els = document.querySelectorAll(‘iframe[src*=”‘ + message.id + ‘”]’); els.forEach(function(el) { el.style.height = message.height + ‘px’; }); }, false); })();

    “It’s not that we’re getting 2 to 4 [inches],” said Staarmann. “We’re going to get a lot of snow.”

    However, some icing was a near certainty throughout the region.

    The ice potential for the Philly region

    The weather service is predicting a quarter-inch of freezing rain, which is probably about the last thing the people at Peco wanted to hear. Freezing rain is a greater threat to power lines and trees than sleet.

    Yes, Peco is well aware of the storm and has crews on standby, said spokesperson Candace Womack.

    Sleet develops when a partially melted snowflake or rain drop freezes on the way to the ground. It doesn’t accumulate efficiently like snowflakes. Freezing rain is rain that doesn’t turn to ice until it lands on a surface and freezes on contact.

    During a winter storm, both hold down snow accumulations. Typically, an inch of liquid precipitation can yield a foot of snow. A similar amount of liquid would yield about 4 inches of sleet.

    (function () {window.addEventListener(‘message’, function (e) { var message = e.data; var els = document.querySelectorAll(‘iframe[src*=”‘ + message.id + ‘”]’); els.forEach(function(el) { el.style.height = message.height + ‘px’; }); }, false); })();

    Both can fall when surface temperatures are well below freezing, if the upper air is warm enough.

    A big difference is that sleet bounces off surfaces, but ice gloms onto them, a menace to power lines and tree branches.

    An ice storm resulted in over 700,000 Peco outages in 2014, a winter record. In that case, freezing rain came 18 hours after a heavy snowfall.

    An overnight freezing rain storm swept through the Philadelphia region Feb. 5, 2014, leaving downed trees and power lines in its wake, along with icicles everywhere as evidenced by these streets signs in Downingtown.

    When will the snow and ice disappear?

    The snow and ice are going to be around for as far as the computer models can see. Temperatures may not get above freezing the rest of the month, as NOAA’s Climate Prediction Center has the odds favoring below normal temperatures through Feb. 6.

    The U.S. model was indicating another storm threat for around Groundhog Day, a week from Monday, Uccellini said.

    Phil might want a pass this year.