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A small craft advisory is a type of wind warning issued by the National Weather Service in the United States. In Canada a similar warning is issued by Environment Canada. It is issued when winds have reached, or are expected to reach within 12 hours, a speed marginally less than gale force. A Small Craft Advisory may also be issued when sea or lake ice exists that could be hazardous to small boats.
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, sleet, graupel, etc.—presenting a hazard, but not expected to produce accumulations meeting storm 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, without meeting a specific other winter criteria. The watch is typically issued 12 to 48 hours before the storm's expected 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.
An ice storm warning is a hazardous weather statement issued by the Weather Forecast Offices of the National Weather Service in the United States which indicates freezing rain produces a significant and possibly damaging accumulation of ice. The criteria for this warning vary from state to state, but typically an ice storm warning will be issued any time more than 1⁄4 inch (6.4 mm) of ice is expected to accumulate in an area; in some areas, the criterion is 1⁄2 inch (13 mm).
At sea, a storm warning is a warning issued by the National Weather Service of the United States when winds between 48 knots and 63 knots are occurring or predicted to occur soon. The winds must not be associated with a tropical cyclone. If the winds are associated with a tropical cyclone, a tropical storm warning will be substituted for the storm warning and less severe gale warning.
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.
A heat advisory is a notice issued by the National Weather Service of the United States. Local offices often have their own criteria. High values of the heat index are caused by temperatures being significantly above normal and high humidities, and such high levels can pose a threat to human life through conditions such as heat stroke.
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.
It is very rare for snow to fall in the U.S. state of Florida, especially in the central and southern portions of the state. With the exception of the far northern areas of the state, most of the major cities in Florida have never recorded measurable snowfall, though trace amounts have been recorded, or flurries in the air observed few times each century. According to the National Weather Service, in the Florida Keys and Key West there is no known occurrence of snow flurries since the European colonization of the region more than 300 years ago. In Miami, Fort Lauderdale, and Palm Beach there has been only one known report of snow flurries observed in the air in more than 200 years; this occurred in January 1977. In any event, Miami, Fort Lauderdale, and Palm Beach have not seen snow flurries before or since this 1977 event.
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.
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.
A river flood watch is issued by the National Weather Service of the United States when flooding at formal forecast points with river gaging sites and established flood stages is possible. Flooding may be caused by various reasons, such as heavy rain in the vicinity of the river, melting snow, and/or ice jams.
A river flood advisory is issued by the National Weather Service of the United States when minor flooding at formal forecast points with river gaging sites and established flood stages is possible. Flooding may have many causes, such as heavy rain in the vicinity of the river, melting snow or ice jams.
A wind chill watch is issued by the National Weather Service of the United States when the wind chill could reach dangerous levels within the next 12 to 48 hours. The exact definition required to issue a watch varies from state to state or from National Weather Service county warning areas to another, but if forecasters believe conditions are favorable for life-threatening wind chills meeting local criteria, a watch will be issued. People going outside should plan to protect themselves against hypothermia and frostbite.
A wind chill warning is a hazardous weather statement issued by local forecast offices of the National Weather Service (NWS) in the United States and previously by the Meteorological Service of Environment and Climate Change Canada (ECCC) when wind chills are forecast to reach values low enough for residents and travelers to be susceptible to life-threatening medical conditions or death associated with accelerated body heat loss.
A gale watch is issued by the National Weather Service of the United States when there is an increased risk for a gale-force wind event, meaning sustained surface winds, or frequent gusts, of 34 to 47 knots, but the occurrence, location, and/or timing of the event is still uncertain.
A Hazardous Seas Watch is issued by the National Weather Service of the United States when there is an increased threat of high wave heights and/or wave steepness values reach a certain criteria, but the occurrence, timing, and/or location are still uncertain. The criteria are set by the local forecast offices. Such tall waves can pose a serious threat to vessels that do not seek shelter.
A Heavy Freezing Spray Watch is issued by the National Weather Service of the United States when there is an increased risk of a heavy spray event that meets the necessary criteria, but the occurrence, timing, and/or location are still uncertain. A watch will be issued when forecasters expect freezing water droplets to be able to accumulate on sea vessels at rates of 2 cm per hour or greater. This accumulation must be caused by an "appropriate combination of cold water, wind, cold air temperature, and vessel movement."
A Heavy Freezing Spray Warning is issued by the National Weather Service of the United States to warn vessels that accumulation of freezing water droplets due to a combination of cold water, wind, cold air, and vessel movement is likely. Accumulation rates of 2 cm per hour or greater must be possible for a warning to be issued.
An Ashfall advisory is a weather advisory issued by the National Weather Service of the United States. Ashfall advisories are issued when there is a likely future or present occurrence of ash rain caused by a large plume of suspended airborne ash, typically caused by large fires or volcanic activity. The National Weather service map color is Dark Grey.
References
- ↑ National Weather Service. "Freezing Spray Advisory". Glossary - National Weather Service. Retrieved 1 June 2011.
- ↑ National Weather Service. "Freezing Spray Advisory" . Retrieved 1 June 2011.