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Severe Thunderstorm Threat From the Central Plains to the Northeast; Extreme HeatRisk for the East Coast

Strong to severe thunderstorms are possible from the central Plains to the Northeast through this evening. Widespread damaging winds are the primary threat but hail and a tornado or two is also possible. Extremely dangerous heat continues across the Eastern U.S. Warm overnight low temperatures will provide little to no relief. Read More >



The National Weather Service (NWS) in Salt Lake City maintains a volunteer spotter network with over 400 people assisting our office. Members of this spotter network are trained to objectively observe and quantify potentially hazardous weather phenomenon and report their findings to the Salt Lake City Weather Forecast Office. Significant weather events in Utah and southwest Wyoming range from high winds, snow and blizzards, to hail and even tornadoes. The services our spotters provide in reporting these events are invaluable to our office. The Utah and Southwest Wyoming Storm Spotter Page is dedicated to giving our spotters online access to resources such as training guides and presentations, information about upcoming training sessions, our spotter newsletter, and more. Additionally, those who have a vested interest in weather can use this page to contact us, and begin the process of becoming an official storm spotter.



A weather spotter is a person who observes significant weather and relays the information to the NWS or appropriate local authority, based on the severity and immediate threat of the event observed.

Spotters provide an invaluable service to their communities and to the NWS. The information they provide helps their community by assisting local public safety officials in making critical decisions aimed at protecting lives and property. During life-threatening weather events such as tornadoes and flash flooding, these real-time reports from weather spotters are used to help warn others in their community, as well as those neighboring communities which may be in harm's way.

Spotter reports also help NWSforecasters in the critical decision making process of determining what storms pose a risk to lives and property. The NWS uses these critical reports from storm spotters in combination with radar, satellite, and automated surface observations when issuing Severe Thunderstorm, Tornado, Flash Flood, Winter Storm, and other types of warnings. Your report becomes part of the warning decision making process, and is combined with radar data and other information and used by NWS forecasters to decide whether or not to:

  • Issue a new warning
  • Cancel an existing warning
  • Continue a warning
  • Issue a warning for the next county
  • Change the warning type (from severe thunderstorm to tornado, for example)

In addition to being used in the warning decision making process by NWS forecasters, spotter reports also provide valuable information to people in the path of a potentially deadly storm. Ground truth reports from spotters help to give credibility to the warnings issued by the NWS to those people who are in the path of a potentially damaging or life-threatening storm. This ground-truth information helps motivate people in harms way to take action to protect themselves and their property.

At times, the NWS may call a spotter after a storm has passed, in order to inquire what conditions were like as the storm moved through. This information helps NWS forecasters train for the next big event. Of course, spotters are always encouraged to take the initiative and call the NWS office with their information.



In order to become an official storm spotter, one must be trained in recognizing different types of weather phenomena when they occur, doing so in a safe manner without putting themselves in danger. Some examples of this include:

  • The ability to determine the strength and type of a storm based on observations of cloud characteristics
  • The ability to differentiate a funnel cloud or tornado from clouds which may appear threatening, but in reality are non-threatening look-alikes to these dangerous weather phenomena.
  • The ability to recognize what types of threats a storm may pose (i.e. lightning, tornadoes, large hail, damaging winds, etc...), and determine what a storm may do in the next 15-30 minutes based on observations of cloud formations within the storm.
  • A detailed knowledge of his or her local area, and the ability to determine when excessive rainfall is likely to result in flooding within this area.
  • The ability to accurately measure snow depth and intensity.
  • A prospective storm spotter can gain this training by attending a 60-90 minute Weather Spotter Training Session presented by a meteorologist from the National Weather Service office in Salt Lake City. These training sessions are offered free of charge to the general public across the area during the late winter and spring months. These sessions are also educational for schoolage children who have an interest in weather. You can view an online version of this presentation here.





Weather Spotter Training 2019



Weather Spotter's Field Guide



Significant Weather Event Reporting Criteria
For links to additional brochures, visit


Below is a current list of severe weather and spotter training scheduled to take place in the next 90 days. Please check this page often to see if new talks have been scheduled or changes have been made to ones already scheduled. If your city or county is not listed, no talk was scheduled in your immediate local area. You are always welcome to attend a talk in a nearby community! All talks are open to the public, last about 90 minutes and are free of charge.



Please report the following IMMEDIATELY to NWS Salt Lake City via:

Download these criteria
  • Twitter using handle @NWSSaltLakeCity
  • Reports/pictures following the event can be sent via email to

Flooding/Flash Flooding/Heavy Rainfall

  • Rapid rise of water along a stream, wash, or low lying area after a heavy rainfalla
  • Water unusually high or flowing faster than normal
  • Water approaching bankfull or nearing roads/structures
  • Inch or more of rainfall observed in a short duration
  • Any observed flooding
  • Debris flows

Winter Weather

  • Snowfall accumulations (how much in what time period)
  • Snow depth
  • Freezing rain accumulation
  • Precipitation type changes

Fire Weather

  • New wildfire threatening life/property
  • Smoke reducing visibilities to less than 2 miles
  • Weather pattern change that could give insight to NWS forecasters

Convective Weather

  • Tornado - Violently rotating column of air that touches the ground
  • Funnel Cloud -Violently rotating column of air that does not reach the ground (watch for rotation)
  • Wall Cloud - An isolated lowering from a cumulonimbus cloudbase that resembles a pedestal (watch for rotation and persistence)
  • Hail of any size
  • Wind Damage - structural, trees uprooted, and/or large healthy limbs down
  • WInd Speed - approximately 50 mph or stronger

Reports should provide as much detail as possible to describe the where, when, how, etc of the event.



Please report hail sizes using the diameter of the largest hailstone, or by referencing an appropriate coin or ball which represents the size of the largest hailstone. Avoid using terms like "marble size hail," as marbles come in different sizes. The table below offers some commonly referenced hail sizes.


Pea .25 inch Golf Ball 1.75 inch
Half-inch .50 inch Hen Egg 2.00 inch
Dime .75 inch Tennis Ball 2.50 inch
Nickel .88 inch Baseball 2.75 inch
Quarter 1.00 inch Tea Cup 3.00 inch
Half Dollar 1.25 inch Grapefruit 4.00 inch
Ping Pong Ball 1.50 inch Softball 4.50 inch



Wind is best measured using an anemometer (an instrument which measures wind speed). If an anemometer is not available, wind speed can be estimated based on the movement of trees, flags, etc... The table below can be used to help estimate wind speed.


30-44 mph (26-39 kt) Whole trees in motion. Inconvenient walking into the wind. Light-weight loose objects (e.g., lawn furniture) tossed or toppled.
45-57 mph (39-49 kt) Large trees bend; twigs, small limbs break and a few larger dead or weak branches may break. Old/weak structures (e.g., sheds, barns) may sustain minor damage (roof, doors). Buildings partially under construction may be damaged. A few loose shingles removed from houses.
58-74 mph (50-64 kt) Large limbs break; shallow rooted trees pushed over. Semi-trucks overturned. More significant damage to old/weak structures. Shingles, awnings removed from houses; damage to chimneys and antennas.
75-89 mph (65-77 kt) Widespread damage to trees with large limbs down or trees broken/uprooted. Mobile homes may be pushed off foundation or overturned. Roof may be partially peeled off industrial/commercial/ warehouse buildings. Some minor roof damage to homes. Weak structures (e.g., farm buildings, airplane hangars) may be severely damaged.
90+ mph (78+ kt) Many large trees broken and uprooted. Mobile homes damaged. Roofs partially peeled off homes and buildings. Moving automobiles pushed off the road. Barns, sheds demolished.



Your severe weather report should be detailed but concise, and should address the following questions:

  • WHAT did you see?
  • WHERE did you see it?   Report the location/approximate location of the event. Be sure to distinguish clearly between where you are and where the event is thought to be happening (“I’m 5 miles north of Mayberry. The tornado looks to be about 5 miles to my northwest”).
  • WHEN did you see it?   Be sure that reports that are relayed through multiple sources carry the time of the event, NOT the report time.
  • Any other details that are important - How long did it last? Direction of travel? Was there damage? etc.


The NWS SKYWARN system is a volunteer network of storm spotters, which number over 230,000 nationally. These volunteers help keep their local communities safe by providing timely and accurate reports of severe weather to the National Weather Service. NWS encourages anyone with an interest in public service and access to communication, such HAM radio, to join the SKYWARN program. Volunteers include police and fire personnel, dispatchers, EMS workers, public utility workers, and other concerned private citizens. Individuals affiliated with hospitals, schools, churches, nursing homes or who have a responsibility for protecting others are also encouraged to become a spotter.



More information on the SKYWARN program can be obtained from the National SKYWARN Page