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.

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:

Tornado Warning
Tornado impact attributeImpact 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
Thunderstorm attributeImpact 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.