Hazard thresholds
Each day column is a UTC day. Times show in your own time zone (the Time button changes it).
Hourly hazards must last at least 3 hours in a UTC day (2 for freezing rain), so a brief shower or gust does not colour the whole day.
How to read the table
- Reference points: each zone is forecast at a named airfield or port (its ICAO code is shown), not at the zone’s geographic centre, which can sit on a mountain range or in empty desert. Most zones also have an alternate airfield or port, forecast as a row of its own. The codes also let the forecasts be checked against the station’s METAR reports later; that scoring is not built yet.
- Likelihood and colour: a percentage is the share of ensemble members that reach a threshold, given with its ICD 203 term. Most hazards use all 82 members; visibility uses GEFS’s 31 and low cloud ECMWF’s 51, because each model publishes only one of them. Colours follow the UK Met Office likelihood-by-impact matrix.
- Tonight’s light: civil dusk and dawn, the moon’s lit fraction at local midnight, and low-light dark: the time with the sun more than 12° below the horizon and the moon down or under a quarter lit.
About Vis
What it is. A program of The Intelligence Company. For each of Watchfloor’s conflict zones, Vis estimates how likely the coming week’s weather is to degrade air, ISR, maritime or ground operations, names the hazard behind it, and gives tonight’s light.
Method. Twice a day, after the 00Z and 12Z ensemble runs reach Open-Meteo, Vis reads every member’s hourly forecast at each point and counts the members that reach each hazard’s amber and red thresholds. Sun and moon are computed with Meeus’s formulas; checked against the US Naval Observatory at four points on 31 Oct 2026, sun times agreed within 1 minute and moon times within 2.
Limits.
- Not an official forecast, and not for flight planning or go/no-go decisions. Use your weather unit or the national meteorological service.
- Thresholds are indicative. Joint doctrine (JP 3-59) names the parameters that matter but publishes no numeric limits, and real limits depend on the platform.
- Each point is read from a model grid of about 25 km, so local effects such as valley fog, sea breezes and single thunderstorms are not resolved. There is no thunderstorm hazard yet.
- Visibility comes from GEFS alone, where it is a diagnosed field that often runs too low in fog and rain.
- Forecasts are not yet scored against observations, so their calibration is unmeasured.
Terms. Provided as is, without warranty. Code under the GNU AGPL-3.0; data under its sources’ licences, below.
Sources
- Ensemble forecasts: Open-Meteo Ensemble API, CC BY 4.0, free for non-commercial use.
- NOAA NCEP GEFS 0.25°, 31 members: US public domain.
- ECMWF IFS ensemble 0.25°, 51 members: ECMWF open data, CC BY 4.0.
- Sun and moon: computed by Vis from Jean Meeus, Astronomical Algorithms.
- Zones: Watchfloor’s conflict zones. Reference points: chosen by Vis (list).
- Fonts: IBM Plex, SIL Open Font License.