Winter storm warning

Last updated

A winter storm warning (SAME code: WSW) is a hazardous weather statement issued by Weather Forecast Offices (WFO) of the National Weather Service (NWS) in the United States to alert the public that a winter storm is occurring or is about to occur in the area, usually within 36 hours of the storm's onset.

Contents

A similar warning is issued by Environment and Climate Change Canada (ECCC) through local forecast offices of the Meteorological Service of Canada.

Definition

Generally, a Winter Storm Warning is issued if the following criteria, at minimum, are forecast: snow accumulations usually between or greater than 4 to 7 inches (10 to 18 cm), or snow accumulations of usually three inches (7.6 cm) or more with significant accumulation of ice (sleet or freezing rain). In the Southern United States, where severe winter weather is much less common and any snow is a more significant event, warning criteria are lower, as low as one inch (2.5 cm) in the southernmost areas: as one goes from north to south, the accumulation estimates needed to meet warning criteria lessen. A warning can also be issued during high impact events of lesser amounts, usually early or very late in the season when trees have leaves and damage can result.

Winter Storm Warnings for snow events are issued when winds are less than 35 mph (56 km/h); if the storm is expected to produce winds above this speed for at least three hours accompanying moderate to heavy snowfall, a blizzard warning will be issued instead or as an upgrade to the winter storm warning. Usually, a large accumulation of ice alone with little to no snow will result in an ice storm warning, or in the case of light freezing rain, a winter weather advisory, a freezing rain advisory, or a freezing drizzle advisory. In lieu of issuing such a statement separately, Winter Storm Warnings can include verbiage indicative of a wind chill advisory or a wind chill warning, if potentially life-threatening wind chill values (determined by local criteria) are forecast to accompany winter precipitation during the warning's duration.

Beginning with the 2008–09 meteorological winter, the National Weather Service consolidated individual precipitation-specific bulletins for winter storms expected to create heavy snowfall ( heavy snow warning ), lake-effect snow ( lake effect snow warning ) or sleet accumulations (sleet warning or heavy sleet warning) within the warned area, replacing them with variants of the Winter Storm Warning product outlining the accordant hazards being forecast:

Winter storm warning for heavy snow
Replaced the heavy snow warning
Winter storm warning for heavy wet snow
Same as above, except when the snow will also be wet
Winter storm warning for heavy snow and blowing snow
When the criteria for both a WSW for heavy snow and a winter weather advisory for snow and blowing snow are met [near-blizzard conditions] [1]
Winter storm warning for heavy sleet
Replaced the sleet warning [2]
Winter storm warning for heavy snow and ice
When both the criteria for a WSW for heavy snow and an ice storm warning are met [3]
Winter storm warning for snow and ice
When both the criteria for a winter weather advisory for snow and an ice storm warning are met
Winter storm warning for sleet and freezing rain
When both the criteria for a winter weather advisory for sleet and an ice storm warning are met
Winter storm warning for heavy lake-effect snow
Replaced the lake effect snow warning in some NWS county warning areas. (2017-2018 season)

Additionally, all of the above warning types may also include verbiage indicative of a wind advisory to indicate strong winds that are expected to accompany the precipitation (e.g., "winter storm warning for heavy wet snow and strong winds").

The generic "winter storm warning" terminology may be used on its own, typically to indicate that all types of winter precipitation (as a mixture or in periods before transitioning between types) are expected in high amounts; however, it may be defined generically at the forecaster's discretion regardless of whether or not this condition is met.

Example of a winter storm warning

[4]

  URGENT - WINTER WEATHER MESSAGE National Weather Service Grand Rapids MI 331 PM EDT Fri Apr 13 2018  MIZ037>040-043>046-050>052-140345- /O.NEW.KGRR.WS.W.0003.180414T0900Z-180415T1600Z/ Mason-Lake-Osceola-Clare-Oceana-Newaygo-Mecosta-Isabella-Muskegon- Montcalm-Gratiot- Including the cities of Ludington, Baldwin, Reed City, Clare,  Hart, Fremont, Big Rapids, Mount Pleasant, Muskegon, Greenville,  and Alma 331 PM EDT Fri Apr 13 2018  ...WINTER STORM WARNING IN EFFECT FROM 5 AM SATURDAY TO NOON EDT SUNDAY...  * WHAT...Heavy mixed precipitation expected. Total snow and sleet   accumulations of two to four inches and ice accumulations of a   quarter to half an inch are expected.  * WHERE...Portions of central and west central Michigan.  * WHEN...From 5 AM Saturday to noon EDT Sunday.  * ADDITIONAL DETAILS...Expect power outages and tree damage due    to the ice. Travel will be impossible. Tree branches could    fall. Expect significant reductions in visibility at times.  PRECAUTIONARY/PREPAREDNESS ACTIONS...  A Winter Storm Warning means significant amounts of snow, sleet and ice will make travel very hazardous or impossible. Strong winds are also expected.   &&  $$ 

See also

Severe weather terminology (United States)

Related Research Articles

Winter storm

A winter storm is an event in which varieties of precipitation are formed that only occur at freezing temperatures, such as snow, mixed snow and rain, or freezing rain. In temperate continental climates, these storms are not necessarily restricted to the winter season, but may occur in the late autumn and early spring as well.

A winter weather advisory is a hazardous weather statement issued by Weather Forecast Offices (WFO) of the National Weather Service in the United States when one or more types of winter precipitation—snow, rain and snow mixed, freezing rain or sleet—presenting a hazard, but not expected to produce accumulations meeting warning criteria, are forecast within 36 hours of the expected onset of precipitation or are occurring in the advisory's coverage area.

A winter storm watch is issued by the National Weather Service of the United States when there is a possibility of heavy snow or potential of significant ice accumulations. The watch is typically issued 12 to 48 hours before the storm's arrival in the given area. The criteria for this watch can vary from place to place, which is true with other winter weather warning and advisories.

Severe weather terminology (United States) Terminology used by the National Weather Service to describe severe weather in the US

This article describes severe weather terminology used by the National Weather Service (NWS) in the United States. The NWS, a government agency operating as an arm of the National Oceanic and Atmospheric Administration (NOAA) branch of the United States Department of Commerce (DoC), defines precise meanings for nearly all of its weather terms.

Severe weather terminology (Canada)

This article describes severe weather terminology used by the Meteorological Service of Canada, a branch within Environment and Climate Change Canada. The article primarily describes various weather warnings, and their criteria. Related weather scales and general weather terms are also addressed in this article. Some terms are specific to certain regions.

A blizzard warning is a hazardous weather statement issued by Weather Forecast Offices (WFO) of the National Weather Service (NWS) in the United States, which indicates heavy snowfall accompanied by sustained winds or frequent gusts of 35 mph (16 m/s) or greater are forecast to occur for a minimum of three hours. A blizzard tends to reduce visibilities to 14 mile (400 m) or less. A Severe Blizzard Warning is a variation issued in some cases of winds above 45 mph (20 m/s) and temperatures below 10 °F (−12 °C). Most local weather offices will activate and broadcast the SAME alarm tone on relevant NOAA Weather Radio stations for both varieties of warning. When the Wireless Emergency Alerts system was launched in 2012, blizzard warnings were initially sent as alerts to mobile phones; this practice was discontinued in November 2013.

A Special Weather Statement is a form of weather advisory. Special Weather Statements are issued by the National Weather Service of the United States and the Meteorological Service of Canada. There are no set criteria for special weather statements in either country.

Rain and snow mixed

Rain and snow mixed is precipitation composed of rain and partially melted snow. Unlike ice pellets, which are hard, and freezing rain, which is fluid until striking an object, this precipitation is soft and translucent, but it contains some traces of ice crystals, from partially fused snowflakes. In any one location, it usually occurs briefly as a transition phase from rain to snow or vice versa. Its METAR code is RASN.

A lake effect snow watch was a bulletin issued by the National Weather Service in the United States to warn of heavy snowfall amounts that will be possible from convective snow generated by cold air masses passing over unfrozen lakes. The criteria for amounts may vary over different county warning areas.

A freezing rain advisory was an advisory issued by the National Weather Service in the United States when freezing rain or freezing drizzle was expected to cause significant inconveniences, but did not meet warning criteria.

Global storm activity of 2007

Global storm activity of 2007 profiles the major worldwide storms, including blizzards, ice storms, and other winter events, from January 1, 2007, to December 31, 2007. Winter storms are events in which the dominant varieties of precipitation are forms that only occur at cold temperatures, such as snow or sleet, or a rainstorm where ground temperatures are cold enough to allow ice to form. It may be marked by strong wind, thunder and lightning, heavy precipitation, such as ice, or wind transporting some substance through the atmosphere. Other major non winter events such as large dust storms, Hurricanes, cyclones, tornados, gales, flooding and rainstorms are also caused by such phenomena to a lesser or greater existent.

2011 Groundhog Day blizzard

The 2011 Groundhog Day Blizzard was a powerful and historic winter storm that affected large swaths of the United States and Canada from January 31 to February 2, 2011, especially on Groundhog Day. During the initial stages of the storm, some meteorologists predicted that the system would affect over 100 million people in the United States. The storm brought cold air, heavy snowfall, blowing snow, and mixed precipitation on a path from New Mexico and northern Texas to New England and Eastern Canada. The Chicago area saw 21.2 inches (54 cm) of snow and blizzard conditions, with winds of over 60 mph (100 km/h). With such continuous winds, the Blizzard continued to the north and affected Eastern and Atlantic Canada. The most notable area affected in Canada was Toronto and the Greater Toronto Area. Blizzard conditions affected many other large cities along the storm's path, including Tulsa, Oklahoma City, Kansas City, St. Louis, Springfield, El Paso, Las Cruces, Des Moines, Milwaukee, Detroit, Chicago, Indianapolis, Dayton, Cleveland, New York City, New York's Capital District, and Boston. Many other areas not normally used to extreme winter conditions, including Albuquerque, Dallas and Houston, experienced significant snowfall or ice accumulation. The central Illinois National Weather Service in Lincoln, Illinois issued only their fourth Blizzard Warning in the forecast office's 16-year history. Snowfall amounts of 20 to 28 inches were forecast for much of Northern and Western Illinois.

2013–14 North American winter

The 2013–14 North American winter refers to winter in North America as it occurred across the continent from late 2013 through early 2014. The winter of 2013–14 was one of the most significant for the United States, due in part to the breakdown of the polar vortex in November 2013, which allowed very cold air to travel down into the United States, leading to an extended period of very cold temperatures. The pattern continued mostly uninterrupted throughout the winter and numerous significant winter storms affected the Eastern United States, with the most notable one being a powerful winter storm that dumped ice and snow in the Southeast and Northeast in mid-February. Most of the cold weather abated by the end of March, though a few winter storms did affect the western portions of the U.S. towards the end of the winter.

2014–15 North American winter

The 2014–15 North American winter refers to winter in North America as it occurred across the continent from late 2014 through early 2015. While both the meteorological and astronomical definitions of winter involve the onset of winter occurring in December, many places in North America experienced their first wintry weather during mid November. A period of below-average temperatures affected much of the contiguous United States, and several records were broken. An early trace of snowfall was recorded in Arkansas. There were greater accumulations of snow across parts of Oklahoma as well. A quasi-permanent phenomenon referred to as the polar vortex may have been partly responsible for the cold weather. Temperatures in much of the United States dropped 15 to 35 °F below average by November 19 following a southward "dip" of the polar vortex into the eastern two-thirds of the country. The effects of this dip were widespread, bringing about temperatures as low as 28 °F (−2 °C) in Pensacola, Florida. Following a significant snowstorm there, Buffalo, New York received several feet of snow from November 17–21. During the 2014–15 winter season, Boston broke its all-time official seasonal 107.6-inch (2.73-meter) snowfall record from the winter of 1995–96, with a total snowfall record of 108.6 inches (2.76 m) as of March 15, 2015.

Late March 2016 North American blizzard

At the start of spring 2016, a major winter storm moved through the High Plains and Midwest, bringing blizzard conditions with snowfall of up to 12–18 inches (30–46 cm) and strong winds as well. Snowstorms like this are typical in these areas at this time of year. The system also brought with it a severe weather threat as well. As it moved to the east, a crippling ice storm scenario was developing as well.

2018–19 North American winter

The 2018–19 North American winter refers to winter in North America as it occurred across the continent from late 2018 through early 2019. Notable events have included a rare snow in the Southeast in December, a strong cold wave and several major winter storms in the Midwest, and upper Northeast and much of Canada in late January and early February, record snowstorms in the Southwest late February, deadly tornado outbreaks in the Southeast and a historic mid-April blizzard in the Midwest, but the most notable event of the winter was a record-breaking bomb cyclone that affected much of the central U.S. and Canada in mid March. Unlike previous winters, a developing weak El Niño was expected to influence weather patterns across North America. Overall, however, winter of 2018–19 was mild along the mid- and lower parts of the East Coast, West Coast, and most of the southern Plains.

2020–21 North American winter 2020-21 North American winter

The 2020–21 North American winter refers to winter in North America as it is occurring across the continent from late 2020 through early 2021. Similar to some recent winters, a developing La Niña pattern is expected to influence the majority of the winter in North America. So far in the season, several notable winter weather events have unfolded, including a crippling ice storm in the Southern Plains, a powerful nor'easter which impacted the Mid-Atlantic and New England states in December, another major nor'easter in February, a strong blizzard in the Midwest during Christmas Week, and snow in parts of the South.

December 15–17, 2020 noreaster North American noreaster in 2020

The December 15–17, 2020 nor'easter was a powerful nor'easter that hammered the Northeastern United States and produced widespread swaths of over 1 foot (12 in) of snow in much of the region from December 15–17, 2020, ending a 1,000+ day high-impact snowstorm drought in much of the Mid-Atlantic and coastal New England regions. The system developed out of a weak area of low-pressure that first developed over the Central United States producing some snowfall before moving eastward, and by December 16, a new, dominant area of low pressure began to develop along the Southeast coast. This low steadily deepened as it moved along and impacted the Mid-Atlantic coastline, prompting several winter-related advisories and warnings for much of the Northeast.

2020–21 New Years North American storm complex

The 2020–21 New Year's North American storm complex was a major storm system that brought a wide swath of snow and ice to parts of the High Plains and Central and Northeastern United States during the New Years holiday from December 30–January 2. The system began developing early on December 30 as and began spreading wintry precipitation to parts of Texas, coalescing into a low pressure system that formed near the western Gulf of Mexico. The winter storm tracked north and brought heavy snow, ice and strong winds to much of the center of the Midwest and interior parts of the Northeast and New England, causing widespread impacts and travel issues.

February 2021 North American ice storm

The February 2021 North American ice storm was a damaging ice storm that impacted the Deep and Upland South and Ohio Valley from February 10–11. The storm also brought wintry precipitation to the Mid-Atlantic states. The system caused over 212,000 power outages and at least 9 fatalities have been confirmed so far, primarily due to accidents involving freezing rain and sleet. It was unofficially named Winter Storm Shirley by The Weather Channel.

References

  1. "Winter Storm Warning In Effect". WDOR. 2014-01-14. Retrieved 2014-04-13.
  2. "Glossary - NOAA's National Weather Service". Weather.gov. 2009-06-25. Retrieved 2014-04-13.
  3. Daryl Herzmann Akrherz. "IEM :: Valid Time Extent Code (VTEC) App". Mesonet.agron.iastate.edu. Retrieved 2014-04-13.
  4. Source - U.S. NOAA National Weather Service