Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >
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| About Skywarn | Training Schedule | Amateur Radio | Spotter Guide | |
Even with all the technology used by the National Weather Service to prepare severe weather warnings, storm spotters still give us the most complete picture of what's really happening in and around severe storms. Radar simply cannot tell us everything we need to know. Storm spotters are the eyes and ears in the field.
For more than 60 years, storm spotters have been the Nation’s first line of defense against deadly storms. Working with their local communities and with the local National Weather Service office, spotters provide invaluable assistance and critical information to decision makers when hazardous weather threatens. Countless lives have been saved because of this unique partnership between volunteer storm spotters, emergency management and the National Weather Service.
For more information on the history of storm spotters, please read Storm Spotting and Public Awareness Since the First Tornado Forecasts of 1948 by Dr. Charles Doswell III, Alan Moller, and Dr. Harold Brooks.
This guide is intended to introduce you to the world of storm spotting. It is NOT intended to replace the official training that is offered by National Weather Service meteorologists each year. Viewing a website cannot substitute for attendance and participation in a 2-3 hour training session, so if you are interested in learning more and becoming a storm spotter, you should contact your local emergency management agency or the National Weather Service.
This guide is divided into four sections:
Please use the menu tabs above to see information for each section.
While everyone should keep a close eye on weather conditions whenever storms threaten, storm spotters have a definite need to know what’s going on before, during and even after a severe weather event. The Norman National Weather Service forecast office, working with the Storm Prediction Center, provides an entire suite of forecast products to keep you informed about severe weather from days to minutes before the storms.
During the height of storm season in the Plains, this is a question that spotters should ask daily. The NWS provides information and forecasts to help answer this question:
Issued by the Storm Prediction Center, these convective outlooks cover the current day, tomorrow and the next day (day three). They are issued for the 48 contiguous states of the U.S. and offer guidance to NWS offices and others on where severe weather may occur.
Based in part on the Storm Prediction Center (SPC) convective outlooks, these outlooks provide a heads-up description of any hazardous weather that’s expected in the next week. The main focus is on today and tomorrow, with more general information provided further into the future.
The HWO is written specifically for storm spotters, emergency managers and others who need specific severe weather forecast information for planning purposes. However, the HWO is available to everyone via the Internet and Weather Radio.
The HWO provides details on what is expected (including what types of storms and hazards), when it is likely to happen and the meteorological reasoning behind it. It is written by NWS forecasters who are the experts in your local area and is updated as often as needed.
This technical discussion comes from your local NWS office and provides the reasoning and explanation behind what the forecasters are thinking. This can be used to supplement the information contained in the Hazardous Weather Outlook.
The local NWS office issues short term forecasts to describe what’s expected in the next few hours over small groups of counties. These forecasts may include information on where storms are anticipated, or details on what existing severe storms are expected to do in the next few hours.
Tornado and severe thunderstorm watches are issued by the National Weather Service’s Storm Prediction Center. Watches typically cover a large geographic area and are in effect for several hours. Watches may prompt the beginning of formal spotter activities in a community.
A watch means conditions are favorable for severe thunderstorms and perhaps tornadoes to develop in and close to the watch area. Remember that people in and close to a watch area should be alert to severe storm development. Also remember that watches are not issued for every single severe storm.
A tornado warning is an urgent message from your local National Weather Service office. The warning means a tornado is imminent or occurring and indicates that immediate action is needed to avoid injury.
A tornado warning is usually based on a combination of radar information and storm spotter observations. Tornado warnings are issued for parts of counties and are in effect for about half an hour.
A tornado warning may prompt local officials to sound outdoor warning sirens.
A severe thunderstorm warning is an urgent message that means a severe thunderstorm (containing hail at least quarter size (1 inch in diameter) and/or winds in excess of 58 mph) is imminent or occurring.
DO NOT IGNORE severe thunderstorm warnings! These warnings give specific details as to what is expected and may cover a wide range of storms from quarter size hail and 60 mph winds to destructive deadly storms producing softball size hail and 100 mph winds. And, severe thunderstorm warnings often precede tornado warnings, giving you even more advance notice that a dangerous storm is nearby.
The NWS issues severe weather statements to update warnings. Statements provide critical new information on a warning, including spotter reports, updated radar analysis, the latest storm motion and expected hazards.
All of the services mentioned above are available on the NWS Norman website - https://www.weather.gov/oun and on NWS Weather Radio.
These reports include the latest severe weather reports received by the National Weather Service, and include the time, location and a description of what happened. Spotter reports are the primary source for local storm report information.
Remember that this website cannot provide you with everything you need to know to be a storm spotter. This is only an introduction to storm spotting and is very general in nature.
If you want to learn more about the meteorology behind storm observations, you should attend a NWS storm spotter training session. These are typically offered during the late winter and early spring and include much more detailed information on storm types, visual clues for severe weather, spotter safety and procedures and severe weather meteorology.
Thunderstorms are common in this part of the world, and most of us are quite familiar with them and the dangerous weather they can bring. Most individual thunderstorms only last several minutes, however some individual thunderstorms become very well-organized and can last several hours. These long-lived thunderstorms are called supercell thunderstorms. Supercell thunderstorms are responsible for the majority of significant severe weather, including very large hail and tornadoes. However, storms that form in organized lines (called squall lines) can also produce widespread strong and damaging winds.
A severe thunderstorm is defined by the National Weather Service as one that produces one or more of the following:
The National Weather Service issues severe thunderstorm warnings and tornado warnings, based in part on observations from storm spotters in the field. Your reports are important to warning forecasters who are making critical warning decisions.
Storm spotters play a vital role in the warning and information process by observing storms and making reports back to the National Weather Service and local public safety officials. Trained spotters learn about the physical structure of severe storms and how to identify the most likely areas for severe weather development. They also learn about visual clues that may precede tornado development, and learn to distinguish between real tornadoes and look-alikes. These types of details, when coupled with NWS forecasters’ expert radar interpretation, lead to better warnings and statements.
The list below outlines some of the key elements spotters look for when observing severe storms:
A violently rotating column of air in contact with the ground and extending from the base of a thunderstorm. A visible funnel does not need to reach to the ground for a tornado to be present; a debris cloud beneath a thunderstorm is all that is needed to confirm the presence of a tornado. Tornadoes can assume a wide variety of shapes, sizes and colors depending on your viewing angle and many other factors.
A funnel extending from the base of a cloud, associated with a rotating column of air that is not in contact with the ground (and hence different from a tornado). A funnel cloud in itself is not dangerous, but provides a clue that a tornado could form very quickly.
A localized, persistent, often abrupt lowering from the base of a thunderstorm. Spotters should know that not all wall clouds produce tornadoes!! Wall clouds can range from a fraction of a mile up to nearly five miles in diameter, and normally are found on the south or southwest side of a supercell thunderstorm. When seen from within several miles, dangerous wall clouds show rapid upward motion and cyclonic rotation. However, not all wall clouds rotate. Rotating wall clouds usually precede significant tornadoes, by anywhere from a few minutes up to nearly an hour. Wall clouds should be watched closely for signs of persistent, sustained rotation and/or rapid vertical motion.
A dark, horizontal cloud base with no visible precipitation beneath it. The rain-free base typically marks the location of the thunderstorm updraft. Tornadoes may develop from wall clouds attached to the rain-free base, or from the rain-free base itself - especially when the rain-free base is on the south or southwest side of the main precipitation area. Note that the rain-free base may not actually be rain free; hail or large rain drops may be falling. For this reason, updraft base is more accurate.
A significant severe thunderstorm with a persistent rotating updraft. Supercells are relatively rare, but are responsible for a remarkably high percentage of severe weather events, including tornadoes, extremely large hail and damaging straight-line winds. On radar, a supercell may have a hook echo and may show strong rotation.
A strong downdraft resulting in an outward burst of damaging winds at or near the ground. Downburst winds can produce damage equal to that of a strong tornado. Downbursts are usually associated with thunderstorms, but can also occur with showers too weak to produce thunder.
To see a more extensive glossary of spotter terms, please read NOAA Technical Memorandum NWS SR-145, A Comprehensive Glossary of Weather Terms for Storm Spotters.
For more specific and detailed information on the meteorological aspects of storm spotting, check out these links:
Accurate and timely spotter reports are critical to your local community and to the National Weather Service. However, your first priority as a storm spotter is to STAY SAFE! Severe storms present a number of hazards, any of which could lead to injury or death if you’re not extremely careful.
Depending on whether you are spotting from your vehicle or from a fixed location (like a home or business), there are hazards you need to be aware of and plan for when you’re observing storms.
Mobile spotters are those who observe storms from their vehicle or from a position other than their home or business. In many communities, spotters have assigned observation locations – when spotters are activated, they go to their designated spot, and observe and report weather conditions. Some mobile spotters stay mobile during the storm and attempt to move along with the storm to maintain a view of the “action area” and report any changes as the storm progresses.
NOTE: The National Weather Service does not condone, endorse or recommend storm chasing. It is a dangerous practice and should not be attempted.
As a mobile spotter, there are important safety considerations you should think about. The following is a partial list of the hazards you may face as a mobile spotter:
Even on a sunny day with no storms, driving a vehicle on a public roadway can be dangerous. When you add storms – with heavy rain, gusty winds, hail, blowing dust, etc – the danger increases dramatically. To stay safe as a mobile spotter, keep these things in mind:
Always spot with a partner – This allows the driver to focus on the road while the passenger watches the sky. This also provides an extra set of eyes to keep an eye on rapidly changing situations.
Watch for water on the road – Hydroplaning is a serious threat for drivers, and it doesn’t take much rain to cause roads to become slick and hazardous.
Obey traffic laws – Speeding, parking too close to the edge of the road and making sudden turns and stops on unfamiliar roads all spell trouble.
Watch out for the “other guy” – Severe storms in the Plains often draw a crowd of onlookers, from casual observers to organized groups of storm chasers. Be extra careful when stopping to view a storm, making sure to pull completely off roadways and keeping an eye out for traffic, even in places where you would never expect to see traffic.
Make sure your vehicle is ready for action – A well-maintained vehicle with a full tank of gas is crucial for a mobile spotter’s safety and success.
All thunderstorms produce lightning, and people are killed and injured each year by lightning. Storm spotters may put themselves at risk from lightning by being in the open, being on a hill or high spot (for better visibility), parking or standing next to metal fences or underneath power lines, standing close to camera tripods or using radio equipment attached to antennae.
Remember that lightning typically provides no warning – the first strike that you see may be the last. Follow these basic lightning safety guidelines:
Avoid being the tallest object, and stay away from other tall objects (like trees, power pole/lines)
Don’t stand close to fences or power poles/lines. Even though you may not be in an area of frequent lightning, lightning can travel a considerable distance along these pathways.
As mentioned before, you should not wait for some type of warning (hair standing on end, sounds on AM or other radio equipment, etc) before taking shelter from lightning – the first strike from a storm could be the one that gets you. Treat lightning with respect and stay in a protected area when lightning is in the area.
CPR training is an excellent idea for all mobile storm spotters. Remember that a person struck by lightning carries no residual charge and CPR could save a life.
If a mobile storm spotter is well trained, experienced and knowledgeable about severe storm structure and behavior, they can usually avoid becoming a victim of the storm itself. However, the environment in and near a severe storm can change dramatically in a short period of time, and these changes can catch you by surprise. These basic tips can help you stay safe:
Avoid the most intense areas of storms – This seems obvious, but each year spotters, for one reason or another, make decisions that place them in the core of a dangerous storm. Storm chasers call this “core-punching” and it’s a very dangerous practice for a number of reasons. First, you may drive into very large hail, which can damage your vehicle and injure you. Second, you could drive right into the path of a tornado with very little time to react. And finally, the core of the storm is a dangerous place with low visibilities, heavy rain, and violent winds.
Keep your head on a swivel – When observing a storm, it is easy to lose focus and become fixated on some feature you’re watching. You should maintain awareness of what’s going on all around you and always be mindful of a surprise event. This points out the importance of spotting with a partner, who can be an extra set of eyes and ears to help you stay safe.
ALWAYS have an escape route in mind – Mobile spotters should always plan an emergency escape route that will take them out of harm’s way should the storm change direction or otherwise threaten them. Determining that escape route requires a great deal of knowledge about the storm’s movement and behavior. A detailed set of current maps of your spotting area is a critical part of a mobile spotter’s toolbox, but be mindful of the fact that roads sometimes change before maps do, and they may not reflect reality in every case.
Never drive into areas where water covers the road – This is especially true when you cannot be certain how deep the water is. Many people die each year by driving into flooded areas and drowning in their vehicles. Find another safer route.
Keep your engine running – Especially when operating close to a severe storm. You do not want to find out about a vehicle problem as a violent storm bears down on you.
Be extra cautious at night – Obviously, it is more dangerous to deal with something you cannot clearly see. Storms at night present special problems for spotters and you should be extremely cautious when observing storms after dark.
When it comes to being safe, storm spotters who observe storms from a fixed location have some advantages, but also some disadvantages as compared to mobile spotters. Fixed spotters may have access to shelter and will not be exposed to the elements and all the hazards that mobile spotters face. However, there are instances when mobile spotters might be able to get out of the path of a dangerous storm, while fixed spotters cannot.
Fixed spotters should be mindful of all the hazards a severe storm can bring, including lightning, large damaging hail, violent straight-line winds, torrential rains and tornadoes. And just like everyone, fixed spotters should have a severe weather safety plan for wherever they may be. Remember these basic safety guidelines:
Tornado safety – Get underground or into a safe room or basement if possible. If none of these are available, get on the lowest floor of a sturdy building, putting as many walls between you and the outside as possible. Avoid windows, doors and outside walls. Cover your head and body to protect yourself from deadly flying debris. Mobile homes and vehicles should be abandoned for more substantial shelter.
Lightning safety – Stay away from doors and windows. Avoid using electrical appliances and stay away from plumbing fixtures, as these can be pathways for lightning to enter a building. Stay off the telephone, especially corded phones, as much as possible.
Hail and wind safety – Severe thunderstorms can produce destructive hail and damaging winds, even without a tornado. Follow the tornado safety rules, especially when a storm contains very large hail and/or violent winds.
Spotters provide an invaluable service to their communities and to the National Weather Service.
Spotter reports help your community by assisting local public safety officials in making critical decisions to protect lives – when to sound sirens, activate safety plans, etc
Spotter reports also help the NWS in the warning process. 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:
For your reports to be the most useful, they should be as detailed, accurate and timely as possible. Use the guidelines below to help you make your report:
Spotter networks usually work best when a central location (an EOC or warning point, for example) collects reports from the local spotter network, then relays a consolidated report to the National Weather Service. This reduces duplicate reports and makes the system flow smoothly.
In this type of network, communication between the spotter and the control point must be clear to avoid misinterpretation. As a report is relayed through multiple sources, the chances for error being introduced into the chain grow.
Look at this example:
ORIGINAL SPOTTER REPORT at 7:30 PM:
“I am 3 miles north of Mayberry on Highway 78. I see a tornado about 5 miles to my northwest. It looks to be moving east along Highway 412”
Spotter report is relayed to another station, who relays it to the county warning point, who relays it to the NWS.
REPORT AS RECEIVED BY NWS at 7:40 PM:
“There is a tornado in Mayberry”
Obviously, the report the NWS received is not accurate – the location and the time are incorrect.
Although reporting criteria may vary slightly depending on the spotter network and local needs, these are the events the National Weather Service would like to know about as soon as possible:
| TORNADO | ||
|---|---|---|
| FUNNEL CLOUD | Organized, persistent, sustained rotation | |
| WALL CLOUD | Organized, persistent, sustained rotation | |
| HAIL | Quarter size or larger | Report the largest size hailstone |
| WIND GUSTS | 58 mph or higher | Specify estimate or measurement |
| FLOODING | Flooding that impacts roads, homes or businesses. | |
| STORM DAMAGE |
Damage to structures (roof, siding, windows, etc) |
Again, reports should provide as much detail as possible to describe the where, when, how, etc. of the event.
| 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 |
| 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.
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