WxAlerts Spotter Library
Section outline
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Where your report enters the warning decision, and where it does not. Seven lessons on what radar cannot see, who else is standing under the storm, how a warning is built and read, and what happens to a report after you make it.
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Radar has known blind spots. This lesson gives you the numbers for them, so you can tell when your eyes are the only instrument with the answer. (30 min)
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Three kinds of people stand under the same storm with three different sets of obligations. Which one you are changes what a forecast office does with your call. (20 min)
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Most of the rules in this course were written after something went wrong. The timeline is the short version of why the warning system has its current shape, and why spotters are still in it. (25 min)
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Six acronyms issue nearly everything you will act on, and they do not do the same job. Knowing which office owns which product tells you who your report is for and when it is worth making. (25 min)
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A warning is a structured document, not a paragraph. Read the structure and you can see which parts came from radar, which came from a person, and which line your own report would land on. (30 min)
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A warning that nobody receives is a file on a server. This lesson follows the product out of the office and finds the places it stops. (20 min)
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Your report does not stop at the forecast office. It scores the warning, enters the national record, and becomes part of the climatology the next generation of forecasts is built on. (30 min)
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What makes a storm, what makes it organized, and what kind you are standing under. Eight lessons from the three ingredients to the bow echo, with equal weight on the storm modes that dominate the Southeast and the ones that photograph well on the Plains.
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Three ingredients make a thunderstorm and a fourth decides what kind you get. Each of them has a number attached, and the numbers are on the same forecast pages you already look at. (35 min)
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An ordinary thunderstorm builds the thing that kills it. Watch the sequence once with that in mind and the timings stop being trivia. (30 min)
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Same moisture, same instability, same lift, different wind profile, completely different day. Shear is the parameter that turns a forecast of storms into a forecast of a storm mode. (35 min)
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The storm that will not look severe, has no rotation to report, lasts half an hour, and puts a tree through somebody's roof. Most of our summer severe weather comes from this. (25 min)
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A cluster can move northeast while every cell in it moves east, or sit still for three hours while its cells race away downstream. Once you can separate the two motions, radar loops stop being confusing. (25 min)
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A supercell is not a big thunderstorm. It is a thunderstorm that has solved the problem in lesson 2, and rotation is how it solves it. (35 min)
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The supercell you were shown in class is a photograph from Kansas. This lesson is about the ones that actually arrive here, most of which you cannot see. (30 min)
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A line of storms is not a big multicell cluster. It has its own dynamics, its own tornado problem, and a definition dispute running through the middle of it that is worth understanding rather than memorising. (40 min)
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Naming what you are looking at, and telling it apart from the thing it resembles. Eleven lessons that work down the storm from the anvil to the ground, ending at the two hardest calls a spotter makes: is that lowering outflow or inflow, and is that a tornado or not.
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Before you can tell two features apart you have to be able to name them. This is the vocabulary the other ten lessons are written in. (20 min)
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Overshooting top, backsheared anvil, striations, flanking line, mammatus. Four of those tell you about the updraft. One of them tells you nothing, and is the most misreported cloud in the sky. (25 min)
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Two regions under a storm, doing opposite things. Getting the boundary between them right is what makes every later lesson possible. (25 min)
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Air being pulled into a storm makes clouds of its own, and two of them are long, low and sinister-looking from the wrong angle. (20 min)
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The cold air a storm makes has to go somewhere, and on its way out it builds the most dramatic and most misreported clouds in severe weather. (25 min)
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Two lowerings. One is the storm breathing out and one is the storm breathing in. Everything about how you report them is different, and this is the call spotters get wrong more than any other. (30 min)
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There is a bright line between a funnel cloud and a tornado, it is written down, and it is not about how the thing looks. (25 min)
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Not every spinning thing under a storm is a tornado, not every tornado comes from a mesocyclone, and the boundary between those two statements is genuinely disputed. (25 min)
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The same storm type in three costumes. One of them shows you everything, one shows you enough, and one shows you nothing while doing everything. (30 min)
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A line of storms gives you a shelf cloud, a lot of wind, and almost none of the visual vocabulary the rest of this module just taught you. (25 min)
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Everything you have learned to identify can be made unrecognizable by the angle you are standing at, the light behind it, or the ten miles between you and it. (20 min)
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Telling storm-scale rotation from everything that resembles it, and knowing which of the two is worth a report. Nine lessons that build from where rotation lives in a supercell to a documented real outbreak, and that spend as much time on the rotation you cannot see as on the rotation you can.
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Where rotation actually lives in a storm, what the word for it means, and why most of it never produces a tornado. (25 min)
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Striations, inflow bands and the beaver tail: what an updraft looks like when it is turning, and how precipitation placement decides how much of it you get to see. (25 min)
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The feature spotters are most often looking for, its definition in full, and the three signals that decide whether it is worth a radio call. (30 min)
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The dry downdraft that wraps around the circulation, the bright slot that gives it away, and why its arrival is the opposite of good news. (30 min)
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Ragged cloud fragments, rain shafts and outflow features generate most bad rotation reports. Here is what they are, and the checklist that stops you filing one. (30 min)
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The one definition every spotter is expected to know cold, and the three near-misses around it. (30 min)
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The technique that separates rotation from drift, the minimum time it takes, and why a photograph can never be a rotation report. (20 min)
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Rotation you cannot see, in a line, inside the rain, or in the dark, and how to be useful anyway. (30 min)
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Everything in this module, applied to one documented event where almost nothing was visible and the warnings went out anyway. (30 min)
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The two numbers a spotter is asked for most often, the thresholds that decide whether they matter, and the well-documented ways both of them come out wrong. Eight lessons that end with why this platform checks a report for plausibility and never throws one away.
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Wet growth, dry growth, and the updraft that has to hold a stone up long enough to build it. Plus the two pieces of hail folklore worth unlearning first. (30 min)
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What counts as severe, what to measure, and which reference objects the NWS asks you not to use. (25 min)
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Reports under-measure, the archive has a seam in it, and the radar product everyone checks against was built to over-forecast on purpose. (30 min)
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Where damaging straight-line wind comes from, the size that separates a microburst from a macroburst, and which of the two your own air mass hands you. Which is the wet kind. (30 min)
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The severe threshold, the NWS estimation chart in full, and the well-documented reason a number you guessed is worth less than a sentence describing what moved. (30 min)
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What fell, which way it fell, and why the same fallen tree means two different wind speeds depending on the ground it stood in. (25 min)
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The shortest lesson in the module, and the one where being wrong costs the most. (20 min)
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Two numbers, the freezing level and the boundary-layer moisture, decide which of these two hazards your region actually hands you. They are not the same everywhere, and the training photographs are from somewhere else. (25 min)
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The hazard that kills more people in an average year than tornadoes, and the one a spotter is least trained to describe. Seven lessons on what the words mean, what makes the rain sit still, why the same rainfall floods five regions five different ways, and what you can actually measure from a roadside.
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Flash flood, flood, coastal flood, debris flow. Four separate events with four separate definitions, quoted rather than summarized. (25 min)
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Rate times duration. The ingredients that set the rate, the configurations that stretch the duration, and why the storm that floods you is often the quiet one. (30 min)
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The same rainfall floods five places five different ways. Which one you live in decides what to watch, what to expect, and which rules of thumb will mislead you. (25 min)
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The numbers, where they come from, why they disagree with each other, and the three sentences of NWS wording worth memorising exactly. (25 min)
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Depth against a curb and a tire, flowing against ponded, a rain gauge read to hundredths, and the difference between a flooded street and a flash flood. (30 min)
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QPE, flash flood guidance, recurrence intervals and FLASH. What they measure, what they do not, and why the heaviest rainfall is the kind the radar estimates worst. Which is biased low by design. (30 min)
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Two documented events with public data, then the reason a flood report gets a wider window and a longer memory than every other report here. (20 min)
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Everything before this taught you to see something. This teaches you to say it in a form a forecaster can act on inside two minutes. Six lessons on the national criteria, copied from the source rather than paraphrased, how to find the part your own forecast office decides for itself, and the wording that separates a usable report from a discarded one.
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Five stages, one of which is preliminary and one of which is permanent, and the documented reasons the archive is not a fair sample of what happened. (25 min)
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The current definition of a tornado, the rule that you do not wait for a funnel to reach the ground, and the moment a waterspout becomes a tornado. (30 min)
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One inch and 58 miles an hour, quoted from the notice that set them, and why no course can tell you your own office's reporting threshold. (30 min)
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The water, tropical, coastal and winter categories, what a tropical cyclone asks of a spotter over two days, and the one rule about lightning that surprises people. (30 min)
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Occurrence time against reporting time, why a warning already being out is a reason to report rather than not to, and the tag ladder your report can push a storm up. (25 min)
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Seven elements, the location mistake almost everybody makes, three coordinate traps, and which channels exist in 2026. (30 min)
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The module built on one uncomfortable fact: the things most likely to kill a spotter are the car and the lightning, and the tornado is a distant third. Eight lessons on driving, lightning, where to stand, what to do when caught, and the decision framework that keeps you from talking yourself into a bad night.
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The risk record, the one tornado that ever killed storm chasers, and why experience did not save the most experienced people in the field. (25 min)
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The behaviors that produce spotter crashes, the two-person rule that prevents most of them, and why fatigue is a weather hazard. (30 min)
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No safe place outside, why your car protects you and what does not, and the half of lightning deaths that happen after the rain stops. (25 min)
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The safe viewing quadrant of a classic supercell, why core-punching is prohibited, and what is inside the notch that looks so inviting. (30 min)
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Five environments, the assumptions lesson 4 makes that each of them breaks, and the one skill that works in all of them: knowing your roads before you need them. (30 min)
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A tornado while driving, an overpass, hail, straight-line wind and water over a road. What the NWS actually says, including where it declines to give you one answer. (30 min)
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Why fixed-location spotting is the real thing rather than the consolation prize, why night changes the answer, and what to have in the car. (20 min)
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The cognitive traps, three checklists borrowed from trades that solved this before us, and the debrief that turns one outing into better judgment for the next. (25 min)
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What the radar is actually measuring, how late it is, and the three things it cannot tell you no matter how good the app is. Ten lessons that end where they should: with what a trained spotter must never report from a screen.
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A network of about 160 radars run by three agencies, each one listening far more than it talks, and each measuring two things that are not what you think they are. (25 min)
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Why the radar sees higher and coarser the further out it looks, what sits directly overhead that it cannot see at all, and how to spot an echo that is not weather. (30 min)
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What a volume scan is, what the low-level supplementary cuts buy you, and the arithmetic that converts data age into distance on the ground. (25 min)
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A logarithmic scale, a conversion that is an assumption rather than a measurement, and the difference between the two reflectivity products your app offers. (25 min)
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Hook echo, inflow notch, weak echo region, three-body scatter spike, bow echo and debris ball. Six shapes, and six limits on what they mean. (30 min)
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Radar measures motion along the beam and nothing else. Everything confusing about the velocity display follows from that one sentence. (30 min)
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Three new fields, one of which answers a question the old radar could not: is what I am looking at even made of water? (30 min)
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One grid built from the whole network, updating every couple of minutes, and four derived products that are estimates rather than observations. (25 min)
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Radar is for knowing where to be and what is coming. It is not a source of observations, and a report sourced from it is not a spotter report. (25 min)
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Six well-documented events from six parts of the country, each illustrating one limitation this module has spent nine lessons describing. (30 min)
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Module 7 taught you what to say. This is about the pipe it travels down: every channel into a forecast office, what your words become at the other end, how a directed net works, where the emergency manager sits, and what to do on the day the cell network is not there.
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A report is only useful if it arrives in time and attributable. Nine ways in, each trading speed against richness against reliability. (30 min)
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The source field is a credibility ranking, it has thirty-one values, and two of the things people assume are on the list are not. (28 min)
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Three license classes, four rules that actually matter, the unlicensed alternatives, and the fact this whole lesson is optional. (30 min)
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Directed nets, how to check in, how to break in when it matters, and why every relay makes a report slightly worse. (28 min)
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What an emergency operations center is, how your report reaches it, and the answer to why the sirens did not sound. (30 min)
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Cellular fails in severe weather, and there is data. A four-layer plan, a kit, and the sentence about when not to use this app. (30 min)
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What you are not authorized to do, what the law does and does not protect you from, and the character of somebody whose reports can be trusted. Seven lessons on federal law that applies everywhere, the principles behind state law that does not, and the ethics that outlive both.
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A trained volunteer with no authority, and a federal immunity that excludes the single most dangerous thing you will do all season. (25 min)
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Government immunity, a forty-year-old case about lobstermen, and the reason a report on this platform will never be labeled a warning. (25 min)
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Five areas of traffic law that catch spotters, taught as principles because the details are different in every state and change most years. (30 min)
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Private land, damage zones, police lines and curfews, and why the most useful thing you can do at a disaster scene is usually to not be in it. (22 min)
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What may not be transmitted, why you identify every ten minutes, and the alert tone you must never put in a video. (28 min)
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Two regulatory lanes for drones, a right to record with real limits, who owns your footage, and the name you may never use. (30 min)
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False reports, fabricated images, when you must help and when you merely may, and the standards nobody enforces. (30 min)
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