2017–18 North American winter
The 2017–18 North American winter saw weather patterns across North America that were very active, erratic, and protracted, especially near the end of the season, resulting in widespread snow and cold across the continent during the winter. Significant events included rare snowfall in the South, an outbreak of frigid temperatures that affected the United States during the final week of 2017 and early weeks of January, and a series of strong nor'easters that affected the Northeastern U.S during the month of March. In addition, flooding also took place during the month of February in the Central  United States. Finally the winter came to a conclusion with a powerful storm system that caused a tornado outbreak and blizzard in mid-April. The most intense event, however, was an extremely powerful cyclonic blizzard that impacted the northeastern United States in the first week of 2018. Similar to the previous winter, a La Niña was expected to influence the winter weather across North America. While there is no well-agreed-upon date used to indicate the start of winter in the Northern Hemisphere, there are two definitions of winter which may be used. Based on the astronomical definition, winter  began at the winter solstice, which in 2017 occurred on December 21, and ends at the March equinox, which in 2018 occurred on March 20. Based on the meteorological definition, the first day of winter is December 1 and the last day February 28.<ref name="NOAA/NWS-Seasons"></ref> Each definition involves a period of approximately three months, with some variability with both definitions containing two months and a week. Winter is often defined by meteorologists to be the three calendar months with the lowest average temperatures. Since both definitions span the calendar year, it is possible to have a winter  storm in two different years. Seasonal forecasts. On October 19, 2017, the National Oceanic and Atmospheric Administration's Climate Prediction Center released its U.S. Winter Outlook. The outlook noted a 55–65% chance that a La Niña would develop. According to CPC Deputy Director Mike Halpert, any such La Niña was expected to be "weak and potentially short-lived", but it could still affect the season. He also noted that La Niña years normally result in colder-than-average, wetter winters in the northern tier of the United States and the inverse conditions across the south. In terms of precipitation, wetter -than-average conditions were favored across the majority of the northern United States, including a region spanning from the northern Rocky Mountains to the eastern Great Lakes in addition to the Ohio Valley, Hawaii, and western and northern Alaska. Drier conditions were anticipated across the entire southern United States. Above-average temperatures were favored across the southern two-thirds of the contiguous United States and along the east coast, as well as in Hawaii and the northern and western parts of Alaska. The outlook favored below-average temperatures in the northern tier, from Minnesota to the Pacific Northwest region as  well as southeastern Alaska. The remainder of the country was assigned equal chances of either above or below-normal temperatures or precipitation. The drought outlook noted that drought was likely to remain in parts of the northern Plains, with recovery likely to the west. The development of limited regions of drought was possible in regions that did not receive rainfall associated with tropical systems during the 2017 Atlantic hurricane season. Seasonal summary. The North American winter of 2017–18 began in the month of November with the highest snow extent in at least one and a half decades, with snow covering  over a quarter of the contiguous United States, 22% more than the same date in 2011, the next-most-recent year with comparable snow coverage at that date. However, this trend did not last through all of the month, with the last week having the least snowfall of that time of year for the same time period. This extensive snowpack was due in part to cold temperatures on an extent not seen since at least 2014 in the early part of the month caused by an Arctic front advancing southward into the northern United States, breaking several record low temperatures  in major cities from the Upper Midwest to the Mid-Atlantic. In Minnesota, at least several places recorded temperatures below on November 10, breaking several record lows – some places reached as low as . In early December, following another outbreak of cold temperatures, a major winter storm impacted the far southern reaches of the United States – areas as far as the southern portions of the Gulf Coast up to the Mid-Atlantic states and New England received a wide swath of accumulating snowfall, significantly hampering travel and knocking power out to tens of thousands. The rest of the month was generally  warmer then average nationwide, primarily in the southwestern United States, and ranked as the third-warmest in historical records. However, towards the end of the month, an outbreak of below-average temperatures impacted much of the continental United States over the holiday, with New York City recording its second-coldest New Year's Eve on record with a temperature of . January and the new year opened with cold temperatures remaining in place across the eastern part of the country, which would continue until the middle of the month. In the first week of 2018, an extremely powerful cyclonic blizzard developed  off the Southeastern United States, explosively deepening as it traveled parallel to the East Coast. The blizzard delivered snow as far south as Florida which rarely sees snowfall at all, and left a wide swath of snowfall totals up to in the Mid-Atlantic and New England. In addition, major coastal flooding occurred with the system as well and killed at least 11 people. The following week around January 12–13, a major winter storm affected much of the Appalachian Mountains and interior New England, and a few days later on January 16, a separate system dumped as much as in  areas of North Carolina, and for the second time in a month brought snowfall to areas of the Florida Panhandle. Another winter storm brought blizzard-like conditions and up to a foot of snow in the Upper Midwest the following week, with the Twin Cities in Minnesota receiving their largest one-day snowfall since December 2010 with falling on January 22. The long-term pattern that brought below-average temperatures to the eastern half of the United States largely abated by the latter part of January, but not before causing drought conditions to expand within the West to its largest  coverage since May 2014, due to above-average temperatures across much of the region. Events. Late October bomb cyclone. Near the end of October, a powerful extratropical cyclone formed in the Atlantic Ocean off of the coast of New England. Rapidly intensifying into a powerful nor'easter, the winter storm was enhanced by moisture left over from Tropical Storm Philippe – which dissipated over Cuba and spawned an unrelated non-tropical low that the nor'easter later absorbed – before hitting New England and eastern Canada. The nor'easter resulted in approximately 1.2 million power outages in New England. The system produced tropical storm-force  sustained winds, reaching 57 mph (92 km/h) in Warwick, Rhode Island, and hurricane-force wind gusts, peaking at 93 mph (150 km/h) in Popponesset, Massachusetts. The system also produced snowfall mainly in the higher elevations, in areas such as West Virginia and some parts of western Maryland. Snowfall totals reached up to over in some spots, causing accidents and requiring snow plowers to be deployed in Preston County. In Canada, Hydro-Québec reported 200,000 customers losing power because of damages due to winds of . It also rained heavily in Quebec and Eastern Ontario, with up to in the  Canadian capital region of Ottawa forcing Prime Minister Justin Trudeau to use an all-terrain vehicle to leave from his second home on Mousseau Lake in Gatineau Park to go to Parliament. Mid-November cold wave. After an exceptionally warm September and October for many places in the Midwestern and Northeastern United States, a strong Arctic airmass entered the Midwest on November 9, resulting in some of the coldest temperatures ever recorded this early in the season. Lake-effect snow fell in places like the Upper Peninsula of Michigan, where the Mackinac Bridge had to be closed due to low  visibility. Chicago on November 10 also reported Lake-effect snow. The timeframe of November 10–11 broke record lows from northern Minnesota to the New York City tri-state area. On November 10, record lows were recorded in the Midwest. Among these November 10 records were five locations in the Upper Midwest that plunged below zero. In addition to the International Falls, Minnesota, the coldest, and even earliest, record lows mentioned above were set in Hibbing, Minnesota , Duluth, Minnesota and Pellston, Michigan , and Merrill, Wisconsin . The Arctic intrusion on November 10 came as a shock to people that had yet to  seen temperatures cold enough for frost, especially in New England. Before then, not only it was one of the warmest Fall seasons to that date, places like Philadelphia and Washington D.C. had yet to see a day/night that was below since the previous Spring earlier that year. The low temperature in Philadelphia early in the morning of November 11 was . This came two degrees within reaching the record set for that day in 1961. Washington D.C. tied their record of that same morning set back in 1973. Many cities in the Great Lakes and Northeast set record lows that  morning, which record lows were recorded as far south as Charlotte, North Carolina. Forecasters even called for an earlier start to winter ahead of this cold wave. Early December winter storm. A strong winter storm affected areas from northeastern Mexico to the Northeastern United States in early December. The origins of the storm were complex, with the initial disturbance forming over the extreme southern United States as a stationary front left behind from a departing extratropical cyclone on December 7. At the same time, a cold air mass was establishing itself into the Deep South. A large plume of moisture  encompassed the entire Gulf Coast, and snow broke out early on December 8 in places that rarely even see snow, including Mexico, southeastern Texas and Louisiana – even in the Florida Panhandle. The storm dropped up to of snow in some parts of the Southeast as it slowly moved eastwards, breaking several snowfall records; meanwhile, a gulf low formed in the Gulf of Mexico the same day – this would ultimately become the dominant low of the system. Transitioning into a nor'easter off the East Coast of the United States, the system began moving parallel to the shoreline, with a large swath  of snowfall accompanying it. The low slowly deepened throughout the day of December 9, bringing the first snow of the season to many parts of the Northeast and New England. Up to 400,000 people were left without power across the affected regions, several schools and roads shut down, and 3 were have confirmed to have been killed by the storm as of December 9. Post-Christmas–mid-January cold wave. In late December, a strong Arctic air mass, due to the weakening of the Northern Polar vortex, came and established from Canada into the Midwestern and Northeastern United States with  the core of the cold centered in the Upper Midwest, Interior Northeast, and Eastern Canada. Temperatures were below average for that time of year. International Falls, Minnesota recorded a record low temperature on December 27 of . In Indianapolis, Indiana, the temperature reached a new low of . In 2017, Watertown, New York and Buffalo, New York each had it coldest final week on record for the year. In St. Louis, Missouri temperatures dropped to on New Year's Day. On January 2, a daily record low in Sioux City, Iowa was set at . Other daily record low temperatures included Cedar Rapids , Iowa , Pierre, South Dakota , South Bend, Indiana , Quincy, Illinois and Lynchburg, Virginia . In their first few days of 2018, the cold front was stretched as far south into the Caribbean. Early January blizzard. A severe blizzard caused disruption along the Eastern United States in the first few days of the new year. It provided snow in municipalities that do not often receive and therefore are not accustomed to handling winter precipitation, such as Georgia and Florida, and accumulated over of snow in New England, the Mid-Atlantic states, and Eastern Canada. The storm started on January 3, 2018, moving rapidly  to the northeast, after which time the system moved east, causing great snowfall. The storm was also dubbed as a "historic bomb cyclone". The blizzard produced snowfall and other forms of frozen precipitation across much of the United States Eastern Seaboard. As of the WPC's fifth winter storm summary, the highest official snowfall amount recorded is in Cape May Court House, New Jersey; however, a snowfall total of was reported in Bathurst, New Brunswick. Freezing rain totals peaked at in Brunswick, Georgia and near Folkston, Georgia. At least twenty-two fatalities were attributed to the storm, including at least  eight car accident-related deaths. At least 4,020 flights were cancelled across the United States, with a majority of cancellations caused by the extensive winter storm. Insurers estimate that claims relating to coastal flooding from the storm will be more than those from snow-related damage. Mid-January winter storms. In mid-January, two winter storms caused widespread disruption across the eastern half of the United States. The first one spread a swath of snow and ice across the northern parts of the Ohio Valley and New England, as a strong cold front pushed through the regions with a developing  low. Several locations received up to a quarter inch of ice while others observed over of snow. The second one, although much less widespread than the first one, crossed Southern, Midwestern, and Northeastern United States and brought snow to places that rarely see it. This storm hit Texas and the Midwest on January 16, 2018. Then, the storm impacted New England and Mid-Atlantic states on January 17. Up to fell in Shreveport, Louisiana, marking the first time more than an inch of snow fell in Shreveport since 2015. Austin, Houston, and San Antonio, Texas saw many vehicle accidents because  of sleet and freezing rain on the morning of January 16. This led to an overwhelming number of vehicular accidents, such as several accidents in the Dallas-Fort Worth metroplex near Canton. In Galveston, hundreds of pipes froze and burst, depleting the city's water reserves to drought levels and forcing Galveston County and Chambers County to implement mandatory water conservation measures until the pipes could be fixed. Florida observed snow for the third time during the winter, with snow and freezing rain observed in portions of the Florida Panhandle. Snow fell in Crestview and DeFuniak Springs while freezing rain  fell in Fort Walton Beach. Pensacola saw sleet which accumulated on grass and vehicles. The Bob Sikes Bridge to Pensacola Beach was closed due to ice. In North Carolina on January 17, Winston-Salem received of snow, Greensboro had to , Burlington had to , and part of Durham had , while areas to the north of Durham had to . Snow fell on portions of the East Coast and Northeast. East Machias, Maine got , Stockbridge, Massachusetts got , Rosendale, New York got , Loyseville, Pennsylvania got , Dover, New Hampshire got , Canaan, Connecticut got , and Wantage, New Jersey got . Late February flooding. Heavy rains led to  intense flooding in the central U.S. from Texas to Michigan in the second half of February, including along the portion of the Ohio River running past Cincinnati and Louisville. Early–late March nor'easters. After a period of record warmth in late February, weather patterns across the continent abruptly became much more active in March. Four powerful nor'easters affected the United States and eastern Canada in that month alone, each dropping more than a foot of snow in the areas affected. March 1–3 nor'easter. The first nor'easter began to take shape over the Mid-Atlantic states at the transition of February  and March. As an area of low pressure moved into the interior Northeast late on March 1, snowfall fell in areas close to the Canada–United States border, while precipitation in coastal areas was rain due to slightly warmer air. Overnight into the early morning hours of March 2, a new area of low pressure formed and rapidly strengthened off the coast of New Jersey, while snow began to slowly increase in coverage near Pennsylvania and southern New York. Wet bulbing helped bring snow to areas closer on the coast, such as New York City. Although the most severe damage  was caused by flooding as well as snow, unusually high tides and storm surges along the coast, wind and downed trees caused massive inland power outages, with the number of outages as high as 1.6 million at one point. As of March 2, at least 15 people are known to have been killed as a result of the storm, five from falling trees or branches. March 6–8 nor'easter. As the first nor'easter occurred, a smaller, but significant blizzard struck the Sierra Nevada mountains and then tracked across the continent as a large weather front, dropping snow across the Midwestern United  States and interior Canada. As it reached the Great Lakes on March 6, another low pressure area formed off the Outer Banks of North Carolina. By mid-afternoon the next day, the two systems had merged into a second nor'easter, which rapidly intensified off the New Jersey coastline and dropped up to over or more of wet snow across much of the Northeast, which hampered the recovery efforts from the first nor'easter. The storm caused up to 1 million people to lose power, and at least 1 person has been confirmed dead due to the storm as of March 7 . Hundreds of flights were cancelled across the region, and many schools closed due to the nor'easter, although some opted to remain open. Many freeways were also closed in the regions, and several states were put under state of emergencies. In Pennsylvania, Governor Tom Wolf declared a state of emergency for several counties in the eastern part of the state. A snow emergency went into effect for the city of Philadelphia on the morning of March 7. Several municipalities in the Philadelphia area declared snow emergencies and many schools and government offices were closed on March 7. Many attractions in the  Philadelphia area either closed early or were closed for the entire day on March 7. The nor'easter had moved off by the morning of March 9, but its remnants stalled over Maritime Canada and persisted throughout the weekend. March 12–14 nor'easter. On the night of March 11, several areas of low pressure developed over the American Southeast and merged into a third nor'easter within 24 hours. On March 13, the storm produced blizzard conditions and a swath of 1–3 feet of snow in New England as it moved northeast into the Gulf of Maine. The storm brought heavy snow blizzard  conditions to Rhode Island on March 13. Blizzard conditions were reported in Newport. Most of the state received at least one foot of snow, peaking at in Foster. The storm brought heavy snow and blizzard conditions to Massachusetts on March 13. Blizzard conditions were reported in several locations including Boston, Hyannis, Falmouth, Plymouth, Marshfield, and Martha's Vineyard. Over two feet of snow were reported in portions of the state, peaking at in Methuen. Wind gusts of were reported at Logan International Airport in Boston while gusts reached on Nantucket Island, in Hyannis, and in East Falmouth. A storm surge  of was reported on Nantucket while a storm surge was recorded in Boston. Over a foot of snow was reported in portions of New Hampshire, with Deefield receiving almost 29 inches and Middleton reported 28 inches. No widespread power outages were reported. The storm brought heavy snow and blizzard conditions to Maine on March 13. Blizzard conditions were reported in Portland. Over a foot of snow was reported in portions of the state. Of the four nor'easters, the third storm was the strongest in terms of minimum pressure, at . March 20–22 nor'easter. The fourth nor'easter began to take shape on  March 19, and lasted until March 23. This nor'easter tracked further south than the previous three, due to an area of high pressure over Quebec and New England. April cold wave. A period of colder-then-average temperatures impacted a large swath of the United States east of the Rocky Mountains from late March to the middle of April, resulting in one of the coldest Aprils for many areas in years, especially the Upper Midwest. This occurred as a result of a persistent pattern throughout much of April favoring high pressure within the Western United States, and troughs within the  eastern half of the country, allowing cold air to funnel down. In the states of Iowa and Wisconsin, the month was the coldest April ever experienced within the states' 124-year record, surpassing April 1907 by . Many states experienced one of their top-ten coldest Aprils on record. The snow cover for most of April was the fifth-largest on record for the U.S. Mid-April blizzard. In mid-April, a powerful weather system created heavy snow and blizzard conditions over much of the upper Midwest, as well as severe weather in the South. Green Bay, Wisconsin reported , its second -heaviest snowstorm of all time and largest ever for the month of April. Further east, a severe ice storm took place. Up to was reported in Lowville, New York, in the foothills of the Tug Hill Plateau. In Ontario, a mix of snow, freezing rain, ice pellets and rain battered Toronto and the surrounding area, causing hundreds of vehicle collisions, flight cancellations, power outages and transportation delays. Freezing rain also caused problems in Ottawa, Montreal, and parts of New Brunswick.