WxAlerts is not affiliated with the National Weather Service. This training is informational and does not confer NWS Trained Spotter status. Official SKYWARN certification is issued by your local NWS forecast office.

Module 05

Hail & wind estimation

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.

Start lesson 01

Lessons8

Reading timeabout 3.5 hrs

Objectives30

The lessons

Take them in order, or don't

01How hail is madeWet 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.Measurement detailStarts before the hail chart, with why the stone is the size it is, because that is what tells you which storms to expect it from.30 min 02Measuring and reporting hailWhat counts as severe, what to measure, and which reference objects the NWS asks you not to use.Measurement detailThe chart, unedited, plus the measurement procedure the chart assumes you already know and does not tell you.25 min 03Why the hail record is wrongReports under-measure, the archive has a seam in it, and the radar product everyone checks against was built to over-forecast on purpose.Measurement detailThe lesson that explains why this platform will never delete your report for disagreeing with radar.30 min 04Downbursts, gust fronts and derechosWhere 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.Measurement detailNames the wind that does most of the damage in this region, which is easy to treat as a footnote to tornadoes.30 min 05Estimating and measuring windThe 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.Measurement detailShows you the evidence that your own wind estimates are biased, and what to do instead.30 min 06Reading wind from damageWhat fell, which way it fell, and why the same fallen tree means two different wind speeds depending on the ground it stood in.Measurement detailThe survey method, at the depth a spotter can actually use it, including the caveat that matters most anywhere the ground is already saturated.25 min 07Staying safe in hail and windThe shortest lesson in the module, and the one where being wrong costs the most.20 min 08Where you are changes the hazardTwo 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.Measurement detailMost hail and wind training is written from the Plains, where the photographs come from. This is the lesson that tells you which parts of it apply to your own sky.25 min

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