Dense Fog Advisory
Dense Fog Advisory


Severe weather terminology (United States)
Blowing Dust Advisory – Strong winds and considerable blowing sand or dust reducing visibilities. Dense Fog Advisory – Widespread or localized fog reducing

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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. This article describes NWS terminology and related weather scales used by the agency. Some terms may be specific to certain cities or regions.

Contents Definitions of severe weather alerts

The NWS divides severe weather alerts into a few types of hazardous weather/hydrologic events:

  1. Severe local storms – Short-fused, small-scale hazardous weather or hydrologic events produced by thunderstorms, including large hail, damaging winds, tornadoes, and flash floods.
  2. Winter storms – Weather hazards associated with freezing or frozen precipitation (freezing rain, sleet, snow) or combined effects of winter precipitation and strong winds.
  3. Fire weather – Weather conditions leading to an increased risk of wildfires.
  4. Flooding – Hazardous hydrological events resulting in temporary inundation of land areas not normally covered by water, often caused by excessive rainfall.
  5. Coastal/lakeshore hazards – Hydrological hazards that may affect property, marine or leisure activities in areas near ocean and lake waters including high surf and coastal or lakeshore flooding, as well as rip currents.
  6. Marine hazards – Hazardous events that may affect marine travel, fishing and shipping interests along large bodies of water, including hazardous seas and freezing spray.
  7. Other hazards – Weather hazards not directly associated with any of the above including extreme heat or cold, dense fog, high winds, and river or lakeshore flooding.
Severe local storms An example of weather alerts on a national map from the National Weather Service. Winter precipitation Deprecated
  • Heavy Snow Warning – Heavy snowfall amounts are imminent; the criteria for amounts vary significantly over different county warning areas.[14]
  • Sleet Warning – Heavy sleet accumulations of 2 inches (5.1 cm) or more in 12 hours or less are imminent. Usually issued as a winter storm warning for heavy sleet.[15]
  • Snow Advisory – Moderate snowfall amounts are imminent; the criteria for amounts vary significantly over different county warning areas.[16]
  • Blowing Snow Advisory – Sustained winds or frequent gusts of 25 to 35 miles per hour (40 to 56 km/h) accompanied by falling and blowing snow, occasionally reducing visibility to 1⁄4 mile (0.40 km) or less.[17]
  • Extreme Cold Watch – Dangerously low temperatures are possible for a prolonged period of time. Frostbite and hypothermia are likely if exposed to these temperatures.
  • Extreme Cold Warning – Dangerously low temperatures are expected for a prolonged period of time. Frostbite and hypothermia are likely if exposed to these temperatures.
  • Lake Effect Snow Watch - Significant amounts of lake-effect snow (generally 6 inches within 12 hours or 8 inches within 24 hours) are possible in the next 12 to 48 hours.
  • Lake Effect Snow Advisory - Moderate amounts of lake-effect snow (generally 3 to 6 inches) are expected or occurring.
  • Freezing Rain Advisory - Accretion of ice up to a quarter of an inch is expected or occurring.
  • Blizzard Watch – Sustained winds or frequent gusts of 35 miles per hour (56 km/h) or greater, considerable falling, and/or blowing snow reducing visibility frequently to 1⁄4 mile (0.40 km) or less for a period of three hours or more are possible generally within the next 48 hours.
Fire weather Flooding Coastal/lakeshore hazards Marine hazards Temperature

See also Windchill section below.

Windchill
  • Wind Chill Warning – Extreme wind chills that are life-threatening are imminent or occurring; the criteria varies significantly over different county warning areas.[29]
  • Wind Chill Advisory – Dangerous wind chills making it feel very cold are imminent or occurring; the criteria varies significantly over different county warning areas.[30]
  • Wind Chill Watch – Extreme wind chills that are life-threatening are possible; the criteria varies significantly over different county warning areas.
Aviation

The following advisories are issued by the National Weather Service Aviation Weather Center (outside of Alaska) or Alaska Aviation Weather Unit. Atmospheric ash plume advisories/warnings are also issued by the United States Geological Survey (Aviation Color Codes).

VAAs are standardized worldwide by the International Civil Aviation Organization.

Other hazards Wind and tropical cyclones

Wind alerting is classified into groups of two beaufort numbers, beginning at 6-7 for the lowest class of wind advisories. The last group includes three beaufort numbers, 14-16. The actual alerts can be categorized into three classes: maritime wind warnings, land wind warnings, and tropical cyclone warnings. Advisory-force and gale-force winds will not trigger a separate wind advisory or warning if a Blizzard warning is already in effect. However, as seen with Hurricane Sandy, if widespread high wind warnings are in effect prior to the issuance of a blizzard warning, the high wind warnings may be continued.

Wind alert terms and signals Wind speed Marine or Beach Hazard Warning Land Warning Tropical Cyclone Warning(s) Flags Lights Beaufort force 25 to 38 mph (22 to 33 knots) Small craft advisory[34] Wind Advisory Wind Advisory or Small craft advisory 6-7 39 to 54 mph (34 to 47 knots) Gale warning[35] High wind warning Tropical storm warning* 8-9 55 to 73 mph (48 to 63 knots) Storm warning[36] High wind warning Tropical storm warning† 10-11 74-110 mph (64 to 99 knots) Hurricane Force Wind Warning[37] High wind warning Hurricane warning 12-13 Over 110 mph (100+ knots) Hurricane Force Wind Warning Extreme wind warning Hurricane warning and Extreme wind warning‡ none none 14-16

* Tropical Storm Warning flags and lights will always be displayed the same as Storm Warning flags and lights.
† A tropical storm with winds in this range is sometimes referred to as a "severe tropical storm".
‡ The Extreme Wind Warning is issued shortly before the eyewall makes landfall

Hazardous weather risks

The various weather conditions described above have different levels of risk. The National Weather Service uses a multi-tier system of weather statements to notify the public of threatening weather conditions. These statements are used in conjunction with specific weather phenomenea to convey different levels of risk. In order of increasing risk, these statements are:

Media distribution

Hazardous weather forecasts and alerts are provided to the public using the NOAA Weather Radio All Hazards system and through news media such as television, radio and internet sources. Many local television stations have overlay graphics which will either show a map or a list of the affected areas. The most common NWS weather alerts to be broadcast over NOAA Weather Radio using SAME technology are described in the following table:

Common NWS weather alerts Event name Code Description Tornado Watch TOA Also known as a red box. Conditions are favorable for the development of severe thunderstorms producing tornadoes in and close to the watch area. Watches are usually in effect for several hours, with six hours being the most common (also automatically indicates a Severe Thunderstorm Watch). Tornado Warning TOR A tornado is indicated by radar or sighted by storm spotters. The warning will include where the tornado is and what locations will be in its path (also automatically indicates a Severe Thunderstorm Warning). Severe Thunderstorm Watch SVA Also known as a yellow box or blue box. Conditions are favorable for the development of severe thunderstorms in and close to the watch area. Watches are usually in effect for several hours, with six hours being the most common. Severe Thunderstorm Warning SVR Issued when a thunderstorm produces hail 1 inch (25 mm) or larger in diameter and/or winds which equal or exceed 58 miles per hour (93 km/h). Severe thunderstorms can result in the loss of life and/or property. Information in this warning includes: where the storm is, what locations will be affected, and the primary threat(s) associated with the storm. Tornadoes can also and do develop in severe thunderstorms without the issuance of a tornado warning. Severe Weather Statement SVS Issued when the forecaster wants to follow up a warning with important information on the progress of severe weather elements. Special Marine Warning SMW Issued when a thunderstorm over water produces hail 1 inch (25 mm) or larger in diameter, causes winds which equal or exceed 39 miles per hour (63 km/h), or is capable of producing or currently producing a waterspout. Information in this warning includes: where the storm is, what waters will be affected, and the primary threat associated with the storm. Flood Watch FLA Issued as either a Flood Watch or a River Flood Watch. Indicates that flooding is possible in and close to the watch area. Those in the affected area are urged to be ready to take action if a flood warning is issued or flooding is observed. Flood Warning FLW Issued as either a Flood Warning or a River Flood Warning. Indicates that flooding is imminent or occurring in the warned area. Flash Flood Watch FFA Also known as a green box. Indicates that flash flooding is possible in and close to the watch area. Those in the affected area are urged to be ready to take quick action if a flash flood warning is issued or flooding is observed. Flash Flood Warning FFW Signifies a dangerous situation where rapid flooding of small rivers, streams, creaks, or urban areas are imminent or already occurring. Very heavy rain that falls in a short time period can lead to flash flooding, depending on local terrain, ground cover, degree of urbanization, degree of man-made changes to river banks, and initial ground or river conditions. Blizzard Watch BZA An announcement for specific areas that blizzard conditions are possible. Blizzard Warning BZW A warning that sustained winds or frequent gusts of 30 kn (35 mph or 56 km/h) or higher and considerable falling and/or blowing snow reducing visibilities to 1⁄4 mile (0.40 km) or less are expected in a specified area. A blizzard warning can remain in effect when snowfall ends but a combination of strong winds and blowing snow continue, even though the winter storm itself may have exited the region (also automatically indicates a Winter Storm Warning for Heavy Snow and Blowing Snow). Tropical Storm Watch TRA An announcement for specific areas that tropical storm conditions are possible within 48 hours. Tropical Storm Warning TRW A warning that sustained winds within the range of 34 to 63 kn (39 to 73 mph or 63 to 117 km/h) associated with a tropical cyclone are expected in a specified area within 36 hours or less. Hurricane Watch HUA An announcement for specific areas that hurricane conditions are possible, and tropical storm conditions are possible within 48 hours. Hurricane Warning HUW A warning that sustained winds 64 kn (74 mph or 118 km/h) or higher associated with a hurricane are expected, and tropical storm conditions are expected within 36 hours in a specified area. A hurricane warning can remain in effect when dangerously high water or a combination of dangerously high water and exceptionally high waves continue, even though winds may be less than hurricane force (also automatically indicates a Tropical Storm Warning). Related weather scales as defined by the NWS

The NWS uses several scales in describing weather events or conditions. Several common scales are described below.

Hail diameter sizes Main article: Hail

The size of individual hailstones that reach surface level is determined by speed of the updraft which create the individual ice crystals at atmospheric levels. Larger hailstones are capable of producing damage to property, and particularly with very large hailstones, resulting in serious injury or death due to blunt-force trauma induced by the impact of the hailstones. Hailstone size is typically correspondent to the size of an object for comparative purposes.

Hailstone size Measurement (in) Measurement (cm) Updraft Speed (mph) Updraft Speed (m/s) pea 0.25 0.6 40 18 penny 0.75 1.9 44 20 quarter* 1.00 2.5 49 22 half dollar 1.25 3.2 54 24 walnut 1.50 3.8 60 27 golf ball 1.75 4.4 64 29 hen egg† 2.00 5.1 69 31 tennis ball 2.50 6.4 77 34 baseball 2.75 7.0 81 36 tea cup 3 7.6 84 38 grapefruit 4 10.1 98 44 softball 4.50 11.4 103 46

* Begins hail sizes within the severe hail criterion.
† Begins hail sizes within the Storm Prediction Center's significant severe criterion.

Beaufort wind scale Main article: Beaufort scale

The Beaufort scale is an empirical measure that correlates wind speed to observed conditions at sea or on land.

Wind category Beaufort number Wind speed Conditions Advisory-force 6 25–31 mph
(40–50 km/h) Large branches in motion; whistling in telephone wires. Advisory-force 7 32–38 mph
(51–62 km/h) Whole trees in motion; inconvenience felt walking against wind. Gale-force 8–9 39–54 mph
(63–88 km/h) Twigs break off trees; wind generally impedes progress. Tropical storm criteria begin. Storm-force 10–11 55–73 mph
(89–117 km/h) Damage to chimneys and television antennas; pushes over shallow-rooted trees. Severe thunderstorm criteria begin (58 mph (93 km/h)). Hurricane-force 12–13 74–112 mph
(118–181 km/h) Peels shingles off roofs; windows broken if struck by debris; trees uprooted or snapped; mobile homes severely damaged or overturned; moving cars pushed off-road. Hurricane criteria begin. Major hurricane-force
Extreme wind 14–16 113–237 mph
(182–381 km/h) Roofs torn off houses; cars lifted off ground; trees defoliated and sometimes debarked. Major hurricane criteria begin.

:Beaufort levels above 12 are non-standard in the United States. Instead, the Saffir–Simpson hurricane scale (Category 1, Category 2, etc.) is used.

Enhanced Fujita tornado intensity scale Main article: Enhanced Fujita scale

The Enhanced Fujita scale, an updated version of the original Fujita scale that was developed by Ted Fujita with Allen Pearson, assigns a numerical rating from EF0 to EF5 to rate the damage intensity of tornadoes. EF0 and EF1 tornadoes are considered "weak" tornadoes, EF2 and EF3 are classified as "strong" tornadoes, with winds of at least major hurricane force, where EF4 and EF5 are categorized as "violent" tornadoes, with winds corresponding to category 5 hurricane winds and rising to match or exceed the strongest tropical cyclones on record. The EF scale is based on tornado damage (primarily to buildings), which makes it difficult to rate tornadoes that strike in sparsely populated areas, where few man-made structures are found. The Enhanced Fujita scale went into effect on February 1, 2007.

EF number Wind speed Comparable hurricane winds Damage Examples 0 65–85 mph (105–137 km/h) Severe tropical storm – Category 1 Light damage. Peels surface off some roofs; some damage to gutters or siding; branches broken off trees; shallow-rooted trees pushed over. Philadelphia (1999); Jacksonville (2004); St. Louis (2007); Windsor, Ontario (2009); Minneapolis (2009) 1 86–110 (138–178 km/h) Category 1–2 Moderate damage. Roofs severely stripped; mobile homes overturned or badly damaged; loss of exterior doors; windows and other glass broken. Houston, (1992), Miami (1997), Bronx, New York (2010); Brooklyn and Queens, New York (2010); Minneapolis (2011) 2 111–135 (179–218 km/h) Category 3 Considerable damage. Roofs torn off well-constructed houses; foundations of frame homes shifted; mobile homes completely destroyed; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground. Salt Lake City (1999); Brooklyn (2007); Atlanta (2008); Vaughan, Ontario (2009); Mobile (2012) 3 136–165 (219–266 km/h) Category 4–5 Severe damage. Entire stories of well-constructed houses destroyed; severe damage to large buildings such as shopping malls; trains overturned; trees debarked; heavy cars lifted off the ground and thrown; structures with weak foundations blown away some distance. St. Louis (1871); Miami (1925); Pine Lake, Alberta (2000); Springfield, Massachusetts (2011); El Reno, Oklahoma (2013) 4 166–200 (267–322 km/h) Strong category 5 Devastating damage. Well-constructed houses and whole frame houses completely leveled; cars thrown and small missiles generated. St. Louis (1896); Regina, Saskatchewan (1912); Worcester (1953); Jackson (2003); Tuscaloosa and Birmingham, Alabama (2011) 5 >200 (>322 km/h) Hurricane Patricia Explosive damage. Strong frame houses leveled off foundations and swept away; automobile-sized missiles fly through the air in excess of 100 m (300 ft); steel reinforced concrete structures badly damaged; high-rise buildings have significant structural deformation; incredible phenomena will occur. Waco (1953); Birmingham (1977); Moore, Oklahoma (1999); Joplin (2011); Moore, Oklahoma (2013) Saffir–Simpson hurricane category scale Main article: Saffir–Simpson scale

The Saffir–Simpson hurricane wind scale, assigns a numerical classification of hurricanes into five categories distinguished by the intensities of their sustained winds. The scale spans from Category 1 (winds of at least 74 miles per hour (119 km/h)) to Category 5 (exceeding 156 miles per hour (251 km/h)). Unlike the Enhanced Fujita Scale, which assigns ratings for tornadoes after damage has been incurred and thoroughly assessed, categories on the Saffir-Simpson scale are assigned to most active cyclones that reach the minimum hurricane threshold, even before landfall.

Category Sustained winds Storm surge Central pressure Potential damage Example(s) 33–42 m/s

74–95 mph
64–82 knot
119–153 km/h

4–5 ft

1.2–1.5 m

28.94 inHg

980 mbar

No real damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Also, some coastal flooding and minor pier damage.[43] Jerry (1989)

Ismael (1995)
Danny (1997)
Gaston (2004)
Kate (2015)

43–49 m/s

96–110 mph
83–95 kt
154–177 km/h

6–8 ft

1.8–2.4 m

28.50–28.91 inHg

965–979 mbar

Some roofing material, door, and window damage. Considerable damage to vegetation, mobile homes, etc. Flooding damages piers and small craft in unprotected anchorages may break their moorings.[43] Carol (1954)

Diana (1990)
Erin (1995)
Marty (2003)
Juan (2003)

50–58 m/s

111–129 mph
96–113 kt
178–209 km/h

9–12 ft

2.7–3.7 m

27.91–28.47 inHg

945–964 mbar

Some structural damage to small residences and utility buildings, with a minor amount of curtainwall failures. Mobile homes are destroyed. Flooding near the coast destroys smaller structures with larger structures damaged by floating debris. Terrain may be flooded well inland.[43] Alma (1966)

Alicia (1983)
Roxanne (1995)
Fran (1996)
Isidore (2002)

Sandy (2012)

59–69 m/s

130–156 mph
114–135 kt
210–249 km/h

13–18 ft

4.0–5.5 m

27.17–27.88 inHg

920–944 mbar

More extensive curtainwall failures with some complete roof structure failure on small residences. Major erosion of beach areas. Terrain may be flooded well inland.[43] "Galveston" (1900)

Hazel (1954)
Iniki (1992)
Iris (2001)
Charley (2004)
Harvey (2017)

≥70 m/s

≥157 mph
≥136 kt
≥250 km/h

≥19 ft

≥5.5 m

<27.17 inHg

<920 mbar

Complete roof failure on many residences and industrial buildings. Some complete building failures with small utility buildings blown over or away. Flooding causes major damage to lower floors of all structures near the shoreline. Massive evacuation of residential areas may be required.[43] "Labor Day" (1935)

"Mexico" (1959)
Camille (1969)
Gilbert (1988)
Andrew (1992)
Irma (2017)

See also References
  1. ^ "National Weather Service glossary: Tornado Watch". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  2. ^ a b "National Weather Service glossary: PDS". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  3. ^ "National Weather Service glossary: Tornado warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  4. ^ a b "Impact Based Warnings". National Weather Service. National Oceanic and Atmospheric Administration. 2014. Retrieved March 12, 2014. 
  5. ^ "National Weather Service glossary: Severe thunderstorm watch". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  6. ^ "National Weather Service glossary: Severe thunderstorm warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  7. ^ "National Weather Service glossary: Flash Flood Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  8. ^ "National Weather Service glossary: Blizzard warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  9. ^ "National Weather Service glossary: Winter storm warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  10. ^ "National Weather Service glossary: Lake Effect Snow Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  11. ^ "National Weather Service glossary: Ice Storm Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  12. ^ "National Weather Service glossary: Winter storm watch". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  13. ^ "National Weather Service glossary: Winter Weather Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  14. ^ "National Weather Service glossary: Heavy Snow Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  15. ^ "National Weather Service glossary: Sleet Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  16. ^ "National Weather Service glossary: Snow Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  17. ^ "National Weather Service glossary: Blowing Snow Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  18. ^ "National Weather Service glossary: Flood Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  19. ^ "National Weather Service glossary: Urban and Small Stream Flood Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  20. ^ a b Storm surge watch & warning to become operational in 2017 (PDF). National Hurricane Center (Report). National Oceanic and Atmospheric Administration. January 23, 2017. Retrieved August 24, 2017. 
  21. ^ "National Hurricane Center's views on the use of scales to communicate the storm surge hazard" (PDF). National Hurricane Center. National Oceanic and Atmospheric Administration. September 2012. Retrieved December 9, 2012. 
  22. ^ "National Weather Service glossary: Freezing Spray Advisory". National Weather Service. National Oceanic and Atmospheric Administration. October 14, 2010. Retrieved December 2, 2010. 
  23. ^ "National Weather Service glossary: Special Marine Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  24. ^ a b c d e f g h i j k l m n o p "WFO NON-PRECIPITATION WEATHER PRODUCTS SPECIFICATION" (PDF). NWS Directives System. National Oceanic and Atmospheric Administration. November 18, 2011. pp. 6–7. Retrieved April 29, 2014. 
  25. ^ "National Weather Service glossary: Excessive Heat Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  26. ^ "National Weather Service glossary: Freeze Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  27. ^ "National Weather Service glossary: Frost Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  28. ^ "National Weather Service glossary: Heat Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  29. ^ "National Weather Service glossary: Wind Chill Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  30. ^ "National Weather Service glossary: Wind Chill Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  31. ^ a b c d "ADDS SIGMET Help". Aviation Weather Center. National Oceanic and Atmospheric Administration. Retrieved April 29, 2014. 
  32. ^ "Washington, DC VAAC - Introduction". NOAA Satellite Information Service. National Oceanic and Atmospheric Administration. Retrieved April 29, 2014. 
  33. ^ "National Weather Service glossary: Dense Fog Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  34. ^ "National Weather Service glossary". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  35. ^ "National Weather Service glossary". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  36. ^ "National Weather Service glossary". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  37. ^ "National Weather Service glossary". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  38. ^ "National Weather Service glossary: Outlook". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  39. ^ "National Weather Service glossary: Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  40. ^ a b "Emergency Alert System (EAS) Event Codes/NWR Specific Area Message Encoding (NWR-SAME) Codes". National Weather Service. National Oceanic and Atmospheric Administration. October 11, 2005. Retrieved August 13, 2012. 
  41. ^ "National Weather Service glossary: Watch". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  42. ^ "National Weather Service glossary: Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009. 
  43. ^ a b c d e National Hurricane Center (June 22, 2006). "Saffir–Simpson Hurricane Scale Information". National Oceanic and Atmospheric Administration. Retrieved 2007-02-25. 
Severe weather terminology in the United StatesSevere
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