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A big batch of new forecast products to alert on

LMKwhen Team
Product updates

This release roughly doubles the forecast data you can build alert rules on — new heat, humidity, precipitation, winter, tropical, and fire-weather products, all usable from the rule wizard today.

Heat & humidity​

  • Heat Stress (WBGT) — Wet Bulb Globe Temperature, the metric used for work/rest scheduling. Alert at or above the NIOSH reference points (82°F alert, 88°F exposure).
  • Max Humidity and Min Humidity — daily relative-humidity extremes. Min Humidity at or below 15% is a common Red Flag / fire-danger criterion.

Precipitation​

  • Precip Probability (12-hour) — chance of measurable precipitation in a 12-hour window.
  • Total Precipitation — running 3-day accumulation through each forecast day.
  • Excessive Rainfall Outlook (WPC) — categorical flash-flood risk (Marginal → High) for Days 1–5. The single best advance signal for flash flooding, often days ahead of any Flash Flood Watch.

Winter​

  • Winter Precip Probability (WPC) — the chance that snow or ice reaches a threshold:
    • Days 1–3: snow ≥ 4 in, ≥ 8 in, ≥ 12 in, and ice ≥ 0.25 in (Slight / Moderate / High probability bands)
    • Days 4–7: extended-range probability of ≥ 0.25 in of snow or sleet (10–90%)

Tropical​

Populated whenever the National Hurricane Center has an active system affecting your locations:

  • Threat levels — hurricane Wind, Storm Surge, Flooding Rain, and Tornado threat (None → Extreme).
  • Wind probabilities — chance of tropical-storm-force (34 kt), 50 kt, and hurricane-force (64 kt) winds.

Fire weather​

  • Dry Thunderstorm Outlook (SPC) — Isolated / Scattered dry-lightning risk, a leading cause of wildfire ignition, issued alongside the fire-weather outlooks.

To use any of these, open the Rules page, start a new rule, and choose the product under the forecast (NDFD) or outlook (SPC / WPC) rule types. Set your threshold and you're done — see the Forecast Products and WPC Outlooks guides for the full details.