2017–18 North American winter: Difference between revisions
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==Events== |
==Events== |
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===Veterans' Day 2017 Cold Wave (November 9-13, 2017)=== |
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A strong Arctic front, which was caused by a displacement of the [[Polar vortex]] in the form of a stratospheric warming event over the [[North Pole]], resulted in a number of record lows for the [[Midwestern]] and [[Northeastern United States]]. This came back 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 {{convert|40|F|C}} since the previous Spring earlier that year. The low temperature early in the morning of November 11 was {{convert|23|F|C}}. This came two degrees within reaching the record set for that day in 1961. Washington D.C. tied their record of {{convert|26|F|C}} that same morning set back in 1973. Forecasters even called for an earlier start to winter ahead of this cold wave.<ref>{{cite news|title=Wood, A. R. (2017, November 09). Freeze warning - could be coldest Veterans Day on record. Retrieved December 28, 2017|url=http://www.philly.com/philly/news/weather/freeze-weather-pennsylvania-new-jersey-veterans-day-20171109.html}}</ref><ref>{{cite news|title=Wood, A. R. (2017, November 13). After record cold, can snow scares be far behind? Retrieved December 28, 2017|url=http://www.philly.com/philly/news/weather/record-cold-weather-snow-scares-philadelphia-20171113.html}}</ref><ref>{{cite news|title=Samenow, J. (2017, November 07). Winter is taking charge early this November, and won’t be super warm like the last two. Retrieved December 28, 2017|url=https://www.washingtonpost.com/news/capital-weather-gang/wp/2017/11/07/winter-is-taking-charge-early-this-november-and-wont-be-super-warm-like-the-last-two/?utm_term=.5b6dd684cfd7}}</ref> |
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===Early December winter storm=== |
===Early December winter storm=== |
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[[File:December 2017 Winter Storm.png|thumb|250px|The snowstorm on December 8 as it was affecting the U.S. Gulf Coast.]] |
[[File:December 2017 Winter Storm.png|thumb|250px|The snowstorm on December 8 as it was affecting the U.S. Gulf Coast.]] |
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Revision as of 01:48, 29 December 2017
| 2017–18 North American winter | |
|---|---|
| Seasonal boundaries | |
| Meteorological winter | December 1 – February 28 |
| Astronomical winter | December 21 – March 20 |
| Seasonal statistics | |
| Total fatalities | Unknown |
| Total damage | Unknown |
The 2017–18 North American winter refers to winter in North America across the continent from late 2017 through early 2018. 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 will occur on March 20.[1] Based on the meteorological definition, the first day of winter is December 1 and the last day February 28.[2] Both definitions involve a period of approximately three months, with some variability.
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.[3]
Seasonal summary
The month of November began with the highest snow extent in at least one and a half decades, with snow covering over a quarter of the contiguous United States,[4] 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.[5]
Events
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.[6] At the same time, a cold airmass 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.[7][8] The storm dropped up to 25 inches (64 cm) 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.[9][10] Transitioning into an extratropical cyclone 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.[10]
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.[8]
Notes
- ^ While the graphic portrays below-average precipitation as favored for Hawaii, the outlook text and other NOAA sources indicate that above-average precipitation is favored.
References
- ^ "Earth's Seasons: Equinoxes, Solstices, Perihelion, and Aphelion, 2000-2025". Washington, D.C.: United States Naval Observatory. August 10, 2017. Archived from the original (PHP) on August 15, 2015. Retrieved October 19, 2017.
{{cite web}}: Unknown parameter|dead-url=ignored (|url-status=suggested) (help) - ^ "Meteorological vs. Astronomical Seasons". NOAA National Centers for Environmental Information. June 21, 2013. Retrieved October 19, 2017.
- ^ "U.S. Winter Outlook: NOAA forecasters predict cooler, wetter North and warmer, drier South: Drought likely to persist in northern Plains". National Oceanic and Atmospheric Administration. October 19, 2017. Retrieved November 11, 2017.
- ^ Erdman, Jonathan (November 8, 2017). "Early November Snow Cover in North America the Highest in Over a Decade". The Weather Channel. Retrieved November 28, 2017.
- ^ Erdman, Jonathan (November 28, 2017). "Lower 48 States Snow Cover Hits Record Low For the Last Week of November". The Weather Channel. Retrieved November 28, 2017.
- ^ "WPC Surface Analysis for 12/07/17". Weather Prediction Center. December 7, 2017. Retrieved December 8, 2017.
- ^ "WPC Surface Analysis for 12/08/17". Weather Prediction Center. December 8, 2017. Retrieved December 9, 2017.
- ^ a b Breslin, Sean. "Winter Storm Benji Targets Northeast After Leaving Nearly 400,000 Without Power In the South, 3 Dead". The Weather Channel. Retrieved December 9, 2017.
- ^ "WPC Surface Analysis for 12/08/17". Weather Prediction Center. December 8, 2017. Retrieved December 9, 2017.
- ^ a b Erdman, Jonathan. "Winter Storm Benji Bringing the Northeast Seaboard's First Snow of the Season After Dropping Record-Setting Deep South Snow". The Weather Channel. Retrieved December 9, 2017.