Severe weather terminology (United States)

Extreme wind warning Tornado Hurricane force wind warning
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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. Specific Area Message Encoding (SAME) product codes assigned to each term for NOAA Weather Radio (NWR) broadcasts are included in parentheses following the title of the described alert type if used; products that do not have a specified code are identified where applicable as Non-Precipitation Warnings/Watches/Advisories (NPW), Coastal Flood Warnings/Watches/Advisories (CFW), Marine Weather Statement (MWS), Surf Discussion (SRD) or Winter Weather Warnings/Watches/Advisories (WSW) as defined by NOAA.

Definitions of severe weather alerts

The NWS divides severe weather alerts into several types of hazardous/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, and/or snow), or combined effects of winter precipitation and strong winds.
  3. Fire weather – Weather conditions that contribute to an increased risk and help cause the spread 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. Tropical cyclone hazards – Hazardous tropical cyclone events that may affect property in inland areas or marine activities in coastal waters, resulting in wind damage, storm surge, tornadoes and flooding rain.
  8. Non-precipitation 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 (WSW) – Heavy snowfall amounts are imminent; the criteria for amounts (based on 12-hour and 24-hour minimum accumulations) vary significantly over different county warning areas.[18]
  • Sleet warning (WSW; alt.: heavy sleet warning) – Heavy sleet accumulations of 1 to 2 inches (2.5 to 5.1 cm) or more, which may cause significant disruptions to travel or utilities, are imminent or expected to occur within in 12 hours. Usually issued as a winter storm warning for heavy sleet.[19]
  • Sleet advisory (WSW) – Moderate sleet accumulations of 14 to 1 inch (0.64 to 2.54 cm) are imminent or expected to occur within 12 hours. Because sleet usually occurs with other precipitation types, a Winter Weather Advisory will almost always be used in such cases.
  • Snow advisory (WSW) – Moderate snowfall amounts are imminent; the criteria for amounts vary significantly over different county warning areas. Under the former definition, a snow advisory could be warranted if lesser snowfall accumulations were forecast to produce travel difficulties, especially early in the winter season. Usually issued as a winter weather advisory for snow.[20]
  • Blowing snow advisory (WSW) – 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 visibilities to 14 mile (0.40 km) or less, will occur for at least three hours. Usually issued as a Winter Weather Advisory for Blowing Snow.[21]
  • Snow and blowing snow advisory (WSW) – Sustained winds of 25 to 35 miles per hour (40 to 56 km/h) are expected to be accompanied by falling and blowing snow, occasionally reducing visibilities to 14 mile (0.40 km) or less for at least three hours. Usually issued as a winter weather advisory for snow and blowing snow.
  • Extreme cold watch (WSW) – Dangerously low temperatures are possible for a prolonged period of time. Frostbite and hypothermia are likely if exposed to these temperatures.
  • Extreme cold warning (WSW) – 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 (WSW) – Significant amounts of lake-effect snow (generally 6 inches (150 mm) within 12 hours or 8 inches (200 mm) within 24 hours) are possible in the next 12 to 48 hours.
  • Lake effect snow advisory (WSW) – Moderate amounts of lake-effect snow (generally 3 to 6 inches [76 to 152 mm]) are expected or occurring.
  • Freezing rain advisory (WSW; alt.: freezing drizzle advisory) – Freezing rain or freezing drizzle producing ice accretion of up to 14 inch (6.4 mm) that may cause significant travel impairments is expected or occurring.
  • Blizzard watch (WSW) – Sustained winds or frequent gusts of 35 miles per hour (30 kn; 56 km/h) or greater, accompanying considerable falling and/or blowing snow, frequently reducing visibilities to 14 mile (0.40 km) or less for a period of three hours or more are possible generally within 12 to 48 hours. The NWS deprecated issuance of blizzard watches in October 2017; a winter storm watch is now issued in its place.

Fire weather

Flooding

Coastal/lakeshore hazards

Marine hazards

Temperature

See also Windchill section below.

Windchill

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.

Tropical weather

Other hazards

Non-meteorological hazards and administrative messages

The National Weather Service also relays messages for non-weather related hazardous events in text products and NOAA Weather Radio broadcasts:[45][46]

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[47] Wind Advisory Wind Advisory or Small craft advisory Small craft warning (USA).jpg Smallcraftlights.gif 6–7
39 to 54 mph (34 to 47 knots) Gale warning[48] High wind warning Tropical storm warning* Gale warning (USA).jpg Galelights.gif 8–9
55 to 73 mph (48 to 63 knots) Storm warning[49] High wind warning Tropical storm warning† Storm warning (USA).jpg Stormlights.gif 10–11
74–110 mph (64 to 99 knots) Hurricane Force Wind Warning[50] High wind warning Hurricane warning Hurricane warning (USA).jpg Hurricanelights.gif 12–13
Over 110 mph (100+ knots) Hurricane Force Wind Warning Extreme wind warning Hurricane warning and Extreme wind warning Hurricane warning (USA).jpg Hurricanelights.gif 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 phenomena to convey different levels of risk. In order of increasing risk, these statements are:

Convective outlook categories

The Storm Prediction Center (SPC) issues Day 1, Day 2, and Day 3 Convective Outlooks depicting forecast areas of general (non-severe) and severe thunderstorm threats across the contiguous United States, along with a text narrative discussion consisting of a plain-language summary of the threat type(s) and timing focused on areas of highest risk, and a technical discussion written in scientific language that usually includes a synoptic overview of convective patterns as well as, if necessary, a geographically specific narrative of meteorological reasoning and justification for the type of coverage and intensity applicable to the severe thunderstorm threat.

The categorical forecast in the Day 1-3 Convective Outlooks—which estimates a severe weather event occurring within 25 miles (40 km) of a point and derives the attendant risk areas from probability forecasts of tornadoes, damaging winds, and large hail on Day 1, and a combined severe weather risk on Days 2 and 3—specifies the level of overall severe thunderstorm risk via numbers, descriptive labeling, and colors as follows: (The Day 4-8 Convective Outlook assesses the percentile probability of severe thunderstorm activity during that period at the 15% and 30% likelihood.)[57]

Convective thunderstorm risk categories
Risk category Map code Description
General or non-severe thunderstorms TSTM Delineates, to the right of a line, where a 10% or greater probability of thunderstorms is forecast during the valid period.
Marginal 1-MRGL An area of severe storms of either limited organization and longevity, or very low coverage and marginal intensity.
Slight 2-SLGT An area of organized severe storms, which is not widespread in coverage with varying levels of intensity.
Enhanced 3-ENH An area of greater (relative to Slight risk) severe storm coverage with varying levels of intensity.
Moderate 4-MDT An area where widespread severe weather with several tornadoes and/or numerous severe thunderstorms is likely, some of which should be intense. This risk is usually reserved for days with several supercells producing intense tornadoes and/or very large hail, or an intense squall line with widespread damaging winds.
High 5-HIGH An area where a severe weather outbreak is expected from either numerous intense and long-tracked tornadoes or a long-lived derecho-producing thunderstorm complex that produces hurricane-force wind gusts and widespread damage. This risk is reserved for when high confidence exists in widespread coverage of severe weather with embedded instances of extreme severe (i.e., violent tornadoes or very damaging convective wind events).

Warning impact statements

Many of the National Weather Service's Weather Forecast Offices—primarily those located within the Central and Southern Region Headquarters—use a multi-tier impact-based warning (IBW) system of impact statements to notify the public and emergency management officials of the severity of specific severe weather phenomena. The impact statement system—initially used only for tornado and severe thunderstorm warnings—was first employed by the WFOs in Wichita and Topeka, Kansas, and Springfield, St. Louis and Kansas City/Pleasant Hill, Missouri beginning with the 2012 Spring severe weather season, eventually expanded to include 33 additional National Weather Service Weather Forecast Offices within the Central Region Headquarters in 2013, and then to eight additional offices within the Eastern, Southern and Western Regions in the spring of 2014.[5]

Under this system, the warning product will include text denoting the specific hazard (i.e., 60 mph wind gusts and quarter size hail) and applicable sourcing (either via indication from Doppler weather radar, or visual confirmation from storm spotters or other emergency management officials) and the level of impact to life and/or property. In order of increasing risk by warning type, these statements—which may be modified at the discretion of the regional forecast office—are:[58]

Tornado Warning[58]
Tornado impact attribute Impact statement(s)
(in sentence order, where applicable)
Landspout / weak tornado
  • Expect damage to mobile homes, roofs, and vehicles.
  • Alternate wording: Expect damage to mobile homes, roofs, screen enclosures, carports, vehicles and trees along the path of the tornado.

(For landspouts and weak tornadoes, alternative impact statements may be utilized at the discretion of the Weather Forecast Office; all other statements are standard nationwide.)

"Base" (default)
  • Flying debris will be dangerous to those caught without shelter.
  • Mobile homes will be damaged or destroyed.
  • Damage to roofs, windows and vehicles will occur.
  • Tree damage is likely.
Considerable
(may accompany wording for a
PDS Tornado Warning or a Tornado Emergency)
  • You are in a life-threatening situation.
  • Flying debris may be deadly to those caught without shelter.
  • Mobile homes will be destroyed.
  • Considerable damage to homes, businesses, and vehicles is likely and complete destruction is possible.
Catastrophic
(accompanies wording for a
PDS Tornado Warning or a Tornado Emergency)
  • You are in a life-threatening situation.
  • Flying debris may be deadly to those caught without shelter.
  • Mobile homes will be destroyed.
  • Considerable damage to homes, businesses, and vehicles is likely and complete destruction is possible.
Severe Thunderstorm Warning[58]
Thunderstorm attribute Impact statement(s)
(in sentence order, where applicable)
Wind (60 mph)
  • 1) Expect damage to roofs, siding, and trees.


Alternate wording:

  • 1) Tree and power line damage is likely.
  • 2) Expect damage to some roofs, siding, carports, and fences.

(This alternate damage impact statement should include both aforementioned statements.)

Wind (70 mph)
  • 1) Expect considerable tree damage.
  • 2) Damage is likely to mobile homes, roofs, and outbuildings.


Alternate wording:

  • 1) Expect considerable tree and power line damage.
  • 2) Damage is likely to mobile homes, roofs, screen enclosures, carports, and outbuildings.
Wind (80 mph)
  • 1) Flying debris will be dangerous to those caught without shelter.
  • 2) Mobile homes will be heavily damaged.
  • 3) Expect considerable damage to roofs, windows, and vehicles.
  • 4) Extensive tree damage and power outages are likely.


Alternate wording:

  • 1) Flying debris will be dangerous to those caught without shelter.
  • 2) Mobile homes will likely be heavily damaged.
  • 3) Considerable damage to roofs, windows, and vehicles is likely.
  • 4) Expect considerable tree and power line damage.
Wind (90 mph)
  • 1) You are in a life-threatening situation.
  • 2) Flying debris may be deadly to those caught without shelter.
  • 3) Mobile homes will be heavily damaged or destroyed.
  • 4) Homes and businesses will have substantial roof and window damage.
  • 5) Expect extensive tree damage and power outages.


Alternate wording:

  • 1) You are in a life-threatening situation.
  • 2) Flying debris may be deadly to those caught without shelter.
  • 3) Mobile homes will be heavily damaged or destroyed.
  • 4) Homes and businesses will likely have substantial roof and window damage.
  • 5) Expect extensive tree damage and power line damage with widespread power outages.
Wind (100 mph+)
  • 1) You are in a life-threatening situation.
  • 2) Flying debris may be deadly to those caught without shelter.
  • 3) Mobile homes will be destroyed.
  • 4) Expect considerable damage to homes and businesses.
  • 5) Expect extensive tree damage and power outages.


Alternate wording:

  • 1) You are in a life-threatening situation.
  • 2) Flying debris may be deadly to those caught without shelter.
  • 3) Mobile homes will be heavily damaged or destroyed.
  • 4) Homes and businesses will likely have substantial roof and window damage.
  • 5) Expect extensive tree damage and power line damage with widespread power outages.
Hail (up to 1.25")
  • Damage to vehicles is expected.


Alternate wording: Damage to vehicles is likely.

Hail (1.50" to 2.50")
  • 1) People and animals outdoors will be injured.
  • 2) Expect damage to roofs, siding, windows, and vehicles.
  • 1) People and animals outdoors will likely be injured.
  • 2) Expect damage to roofs, siding, screen enclosures, windows, and vehicles.
Hail (2.75"+)
  • 1) People and animals outdoors will be severely injured.
  • 2) Expect shattered windows, extensive damage to roofs, siding, and vehicles.


Alternate wording:

  • 1) Severe injuries are likely with hail this size.
  • 2) Expect shattered windows, extensive damage to roofs, siding, screen enclosures, and vehicles.

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 14 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

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

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

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

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)
Saffir-Simpson Category 1.svg 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.[59] Jerry (1989)

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

Saffir-Simpson Category 2.svg 43–49 m/s

96–110 mph
83–95 kn
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.[59] Carol (1954)

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

Saffir-Simpson Category 3.svg 50–58 m/s

111–129 mph
96–113 kn
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.[59] Alma (1966)

Alicia (1983)
Roxanne (1995)
Fran (1996)
Isidore (2002)
Sandy (2012)

Saffir-Simpson Category 4.svg 59–69 m/s

130–156 mph
114–135 kn
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.[59] "Galveston" (1900)

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

Saffir-Simpson Category 5.svg 70 m/s
157 mph
136 kn
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.[59] "Labor Day" (1935)

Camille (1969)
Gilbert (1988)
Andrew (1992)
Wilma (2005)
Irma (2017)
Michael (2018) Dorian (2019)

See also

References

  1. ^ a b c d e f g h "NATIONAL WEATHER SERVICE INSTRUCTION 10-511: WFO SEVERE WEATHER PRODUCTS SPECIFICATION" (PDF). National Weather Service Analyze, Forecast, and Support Office. National Oceanic and Atmospheric Administration. August 20, 2018. Retrieved January 7, 2020.
  2. ^ "National Weather Service glossary: Tornado Watch". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  3. ^ a b "National Weather Service glossary: PDS". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  4. ^ "National Weather Service glossary: Tornado warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  5. ^ a b c "Impact Based Warnings". National Weather Service. National Oceanic and Atmospheric Administration. 2014. Retrieved March 12, 2014.
  6. ^ "National Weather Service glossary: Severe thunderstorm watch". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  7. ^ "National Weather Service glossary: Severe thunderstorm warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  8. ^ a b c d e f g "NATIONAL WEATHER SERVICE INSTRUCTION 10-922: WEATHER FORECAST OFFICE WATER RESOURCES PRODUCTS SPECIFICATION" (PDF). National Weather Service Analyze, Forecast, and Support Office. National Oceanic and Atmospheric Administration. December 6, 2019. Retrieved January 7, 2020.
  9. ^ "National Weather Service glossary: Flash Flood Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  10. ^ a b c d e f g "NATIONAL WEATHER SERVICE INSTRUCTION 10-513: WFO WINTER WEATHER PRODUCTS SPECIFICATION" (PDF). National Weather Service Analyze, Forecast, and Support Office. National Oceanic and Atmospheric Administration. April 13, 2019. Retrieved January 7, 2020.
  11. ^ "National Weather Service glossary: Blizzard warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  12. ^ "National Weather Service glossary: Winter storm warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  13. ^ "National Weather Service glossary: Ice Storm Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  14. ^ "National Weather Service glossary: Winter storm watch". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  15. ^ "National Weather Service glossary: Winter Weather Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  16. ^ "National Weather Service glossary: Lake Effect Snow Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  17. ^ "National Weather Service glossary: Snow Squall". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved December 18, 2019.
  18. ^ "National Weather Service glossary: Heavy Snow Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  19. ^ "National Weather Service glossary: Sleet Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  20. ^ "National Weather Service glossary: Snow Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  21. ^ "National Weather Service glossary: Blowing Snow Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  22. ^ "National Weather Service glossary: Flood Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  23. ^ "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.
  24. ^ a b c d e "NATIONAL WEATHER SERVICE INSTRUCTION 10-604: TROPICAL CYCLONE NAMES AND DEFINITIONS" (PDF). NWS Directives System. National Oceanic and Atmospheric Administration. May 10, 2018. Retrieved January 7, 2020.
  25. ^ 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.
  26. ^ "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.
  27. ^ a b c d e f g h i j k l m n o p q r s t u v "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.
  28. ^ "National Weather Service glossary: Freezing Spray Advisory". National Weather Service. National Oceanic and Atmospheric Administration. October 14, 2010. Retrieved December 2, 2010.
  29. ^ "National Weather Service glossary: Special Marine Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  30. ^ "National Weather Service glossary: Excessive Heat Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  31. ^ a b "Weather Watch, Warning and Advisory Criteria". National Weather Service Baltimore-Washington. Retrieved January 7, 2020.
  32. ^ "NWS Tests Extreme Cold Warning". The Weather Channel. The Weather Company LLC. January 4, 2011. Archived from the original on June 9, 2013.
  33. ^ "National Weather Service ditching 'extreme cold' warnings". Bismarck Tribune. April 15, 2011.
  34. ^ a b "National Weather Service Public Information Statement PNS18-11" (PDF). Retrieved February 1, 2019.
  35. ^ a b "Update on Winter Weather Initiatives Partner Webinar" (PDF). Retrieved February 1, 2019.
  36. ^ "National Weather Service glossary: Freeze Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  37. ^ "National Weather Service glossary: Frost Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  38. ^ "National Weather Service glossary: Heat Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  39. ^ "National Weather Service glossary: Wind Chill Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  40. ^ "National Weather Service glossary: Wind Chill Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  41. ^ a b c d "ADDS SIGMET Help". Aviation Weather Center. National Oceanic and Atmospheric Administration. Retrieved April 29, 2014.
  42. ^ "Washington, DC VAAC – Introduction". NOAA Satellite Information Service. National Oceanic and Atmospheric Administration. Retrieved April 29, 2014.
  43. ^ a b c "NATIONAL WEATHER SERVICE INSTRUCTION 10-601: WEATHER FORECAST OFFICE TROPICAL CYCLONE PRODUCTS" (PDF). NWS Directives System. National Oceanic and Atmospheric Administration. June 1, 2019. Retrieved January 7, 2020.
  44. ^ "National Weather Service glossary: Dense Fog Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  45. ^ "NATIONAL WEATHER SERVICE INSTRUCTION 10-518: NON-WEATHER EMERGENCY PRODUCTS SPECIFICATION" (PDF). National Weather Service Analyze, Forecast, and Support Office. National Oceanic and Atmospheric Administration. August 5, 2019. Retrieved January 7, 2020.
  46. ^ "Non-weather Related Emergency Messages". National Weather Service Memphis, Tennessee. Retrieved January 7, 2020.
  47. ^ "National Weather Service glossary: Small Craft Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  48. ^ "National Weather Service glossary: Gale Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  49. ^ "National Weather Service glossary: Storm Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  50. ^ "National Weather Service glossary: Hurricane Force Wind Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  51. ^ "National Weather Service glossary: Outlook". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  52. ^ "Weather Watch, Warning and Advisory Criteria". National Weather Service Weather Forecast Office Baltimore/Washington. Retrieved January 7, 2020.
  53. ^ "National Weather Service glossary: Advisory". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  54. ^ 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.
  55. ^ "National Weather Service glossary: Watch". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  56. ^ "National Weather Service glossary: Warning". National Weather Service. National Oceanic and Atmospheric Administration. June 25, 2009. Retrieved October 25, 2009.
  57. ^ "SPC Products". Storm Prediction Center. National Oceanic and Atmospheric Administration. Retrieved January 7, 2020.
  58. ^ a b c "National Weather Service Instruction 10-511: WFO Severe Weather Products Specification" (PDF). National Weather Service Operations and Services. August 20, 2018. Retrieved January 5, 2020.
  59. ^ 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.