The 2011 Halloween nor'easter, sometimes referred to as "Snowtober," "Shocktober," "Storm Alfred," and "Oktoberblast," was a large low pressure area that produced unusually early snowfall across the Canadian Maritimes and the northeastern United States. It formed early on October 29 along a cold front to the southeast of the Carolinas. As it moved up the East Coast, its associated snowfall broke records in at least 20 cities for total accumulations, resulting in a rare "white Halloween" two days later.

The storm arrived just two months after Hurricane Irene caused extensive power outages and property damage in the Northeast; with the 2011 New England tornado outbreak also causing damage in Western Massachusetts. It dumped snow on trees that were often still in leaf, adding extra weight, with the ground in some areas still soft from a preceding warm, rainy period that increased the possibility trees could be uprooted. Trees and branches that collapsed caused considerable damage, particularly to power lines, with estimates of storm costs ranging between $1 billion and $3 billion. In all, 3.2 million U.S. residences and businessesTransmission Facility Outages During the Northeast Snowstorm of October 29–30, 2011, Federal Energy Regulatory Commission and North American Electric Reliability Corporation, 2012-05-12, pages 5-8. Retrieved 2014-05-03. in 12 states experienced power outages, with the storm also impacting three Canadian provinces.

Some customers in Connecticut did not get power back until early November; many outages lasted 11 days.Transmission Facility Outages During the Northeast Snowstorm of October 29–30, 2011, Federal Energy Regulatory Commission and North American Electric Reliability Corporation, May 12, 2012, 8 Many communities chose to postpone celebrations of Halloween from two days to a week later as a result, or cancel them entirely. Delays in restoring power led to the resignation of the chief operating officer of Connecticut Light & Power amid widespread criticism of the company's mishandling of both the nor'easter and Irene.http://www.ctpost.com/news/article/Butler-resigns-as-CL-P-chief-2274349.php "Butler resigns as CL&P chief," Connecticut Post, 2011-11-18. Retrieved 2014-05-03.

Meteorological history

Early on October 28, 2011, a ridge over Canada advected an unseasonably cold air mass across the Mid-Atlantic states and New England; at the same time, a surface low-pressure area began developing along the coast of Louisiana. A cold front moved eastward from the Ohio Valley and exited the East Coast of the United States, developing another low pressure area off the coast of the Carolinas on October 29. The remnants of Hurricane Rina had also been absorbed into the developing system. At the same time, an area of precipitation extended from South Carolina through Pennsylvania, mostly falling as rain with some snow observed at higher elevations. By late that morning, the system was producing precipitation over much of the Mid-Atlantic and New England.

As the system moved to the northeast through the day, it produced widespread snow and winds near hurricane-strength north of the cyclone's warm front over the open waters of the Atlantic Ocean. Winds as high as were observed in Massachusetts, and the National Weather Service, issued a Hurricane Force Wind Warning for the Gulf of Maine and other high seas off New England. Overnight into October 30, the storm passed south of Nantucket, and it moved over Nova Scotia later that day with a barometric pressure of . As it did so, the associated precipitation diminished over New England and moved into Atlantic Canada. As the system moved out into the Atlantic Ocean, it reached a minimum barometric pressure of as it passed to the east of the island of Newfoundland late on October 31. By the early morning of November 1, the system had fully moved out to sea. The storm then hit the UK as Cyclone Quinn.

Preparations

Before the storm was at its strongest, local National Weather Service offices issued winter storm warnings from northwestern Virginia through central New England, as well as winter storm watches from central Maryland through central Maine. Officials anticipated peak snowfall totals to be from across much of the region. All warnings were canceled after the storm moved away from the region.

Early on October 29, the Pennsylvania Department of Transportation activated their fleet of salt trucks. In eastern Pennsylvania, the most recent significant snowstorm during October was in 1972. Utility crews prepared additional crews in the event of power outages. The Delaware Water Gap National Recreation Area closed a road due to the storm's threat. Connecticut governor Dan Malloy opened the state's Emergency Operations Center in Hartford, which included members of the transportation, health, and energy departments. Officials opened 41 shelters in Connecticut. Occupy Wall Street protesters pledged to remain in Lower Manhattan's Zucotti Park despite the weather, obtaining coats and blankets.

Snowfall totals and records Precipitation began falling in North Carolina and Virginia late on October 28. By early the next day, measurable snowfall had been reported from West Virginia through Maryland, and eventually as far north as Maine. The deepest snowfall reported was , at Peru, Massachusetts. At least 20 cities reported record-breaking totals, and the peak of in West Milford, New Jersey broke that state's record for highest snowfall in October. Newark, New Jersey's largest city, also broke its all-time October snowfall record with . Central Park in Manhattan observed , also a record. In fact, this was New York City's 3rd October snowfall on record.Snowstorm causes havoc in NYC – what went wrong?, CBS News, November 16, 2018 Hartford, Connecticut's state capital, observed a record , and the highest total in the state was in Farmington southwest of Hartford; this, too, broke the state record for an October snowfall.

In Massachusetts, the nor'easter brought wind gusts peaking at in Barnstable and, unofficially, in Provincetown. An automated marine weather station at Mount Desert Rock off the coast of Maine recorded a top gust of . In Concord, New Hampshire this became the largest 24 hour snowstorm on record.

+ Effects by state or province State/Province Deaths Power outages Maximum SnowfallConnecticut 10 830,000 Maine 0 160,000 Maryland 0 43,000 Massachusetts 6 420,000 New Brunswick 3 3,500 N/ANew Hampshire 0 315,000 New Jersey 8 700,000 New York 3 300,000 Nova Scotia 0 40,000 Pennsylvania 8 500,000 Prince Edward Island 1 3,000 Rhode Island 0 20,000 Vermont 0 7,500 Virginia 0 >4,000 West Virginia 0 43,000 Total39 >3,385,000

Impact

The nor'easter storm became the 14th multibillion-dollar weather-related disaster of 2011, breaking the three-year-old record of nine. Across the Northeast, the combination of high winds and wet, heavy snow downed trees, most of which retained their leaves, did extensive damage. In New York City, a thousand trees were estimated to have fallen in Central Park, far more than had been damaged by Hurricane Irene two months earlier, just as had been reported in Connecticut. The New York Botanical Garden in the Bronx reported that 2,200 trees in the Thain Family Forest, its old-growth forest and the only one remaining in the city from the era prior to European colonization, were damaged. Downed trees caused widespread power outages, leaving over 3 million people without power. In Central Park workers put a priority on making the park safe for the annual New York City Marathon the following weekend.

Fatalities Traffic accidents killed at least six people. Two were electrocuted by downed power lines. Overall, there were 39 deaths.

Transportation The storm affected transportation across the Northeast. Two rail services were closed in the New York area, and Amtrak service across the region was either delayed or canceled. NJ Transit suspended service on the Morris and Essex Lines until November 1 due to downed wires and branches, and even then was only able to restore service as far west as Lake Hopatcong. North of New York City, Metro-North suspended commuter rail service on the Harlem Line north of North White Plains, leaving passengers marooned on a train at Southeast for 11 hours when fallen trees blocked the tracks in both directions. Service was also suspended on the Port Jervis Line and the New Canaan, Danbury and Waterbury branches of the New Haven Line. Service on the Port Jervis Line and electrified portions of the Harlem Line was restored on Monday; bus service replaced trains between Southeast and Wassaic and on the Danbury and Waterbury branches for the rest of the week.

The storm also disrupted air travel from Pennsylvania through Connecticut. Officials at Newark International Airport canceled all flights after 4 pm on October 29, and flights out of New York's two major airports were delayed by up to five hours. Some flights bound for New York were diverted to Hartford. Several JetBlue flights departing from Bradley International Airport there were stranded on the tarmac for up to seven hours due to the hazardous conditions. Teterboro Airport was closed due to the snow and ice.October Nor'Easter Thrashes the Tri-State, NBC New York, October 29, 2011

Some roads were also affected. Along the Jersey Shore, the nor'easter produced coastal flooding that left Ventnor Heights isolated. Officials closed a portion of the Black Horse Pike in West Atlantic City due to flooding. Further north, the flooding closed five New Jersey state highways in Monmouth and Ocean counties. In New York, motorists were stranded for up to 12 hours on the Taconic State Parkway due to the snowfall.

Sports Sporting events on Saturday, mostly college and high school football games, were also impacted. Penn State officials limited parking at its home game in State College to 1,500 spaces due to the inclement weather. It was the first Nittany Lions home October football game with measurable snow since record-keeping began in 1896. At West Point, New York, Army defeated Fordham 55–0 in its first home game played in snow since 1985. On Long Island where a windswept mixture of heavy snow and rain fell, a match between Plainview – Old Bethpage John F. Kennedy High School and Valley Stream Central High School was cancelled after 15 players were treated for hypothermia, prompting the former school district to reconsider game cancellation policies. At another football game on Long Island 10 players were checked and some treated for the condition. Several players at Farmingdale High School reported extreme fatigue for several weeks following playing in the storm.

Halloween Many traditional Halloween activities were affected by the storm. In communities without electricity, where tree limbs and wires were down, trick-or-treating was delayed until days when it was expected to be back and repairs had made the streets safer. This also occurred in communities where electricity was still fully or partially on but the streets still may have been unsafe. In Sleepy Hollow, New York, a popular destination for the holiday since Washington Irving's classic short story, "The Legend of Sleepy Hollow" is set there, Halloween events were canceled due to the storm and its aftermath. On the other hand, another popular Halloween destination, Salem, Massachusetts, location of the 1692 witch trials, was unaffected due to its minimal snowfall.