Glyder Fawr to the Bannau
Forecast 12 hours ahead
Glyder Fawr was on the edge of a Likely area the night before, and Very likely by morning. The webcam was stuck in cloud, but Morgan and Neil were up above it.
Read the forecast checkForecast vs reality
What we forecast, and what people saw.
We save our forecasts ahead of time, then line them up with photos and reports from people who were actually out there. We’ll tell you what we got right, and what we didn’t.
The short answer
What counts as a match?
A match means our forecast covered the right place at the right time. If the map showed an inversion area around the spot when the photo was taken, it counts. Conditions can still vary between nearby summits and valleys.
We picked these checks because they’re useful examples. They show what matched and sometimes what didn’t, but they aren’t a measure of our overall accuracy.
Forecast checks
4 forecast checks, newest events first
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Saved forecast map -
Yr Wyddfa
Forecast 31 hours ahead
Saved forecast map By the night before, Yr Wyddfa was Very likely. The summit webcam and a first-hand report both show it above a cloud sea across Eryri.
Read the forecast check -
Torridon to Tap o’ Noth
Forecast 46 hours ahead
Saved forecast map The Very likely area over the Highlands held right up to the final update. Walkers at Tap o’ Noth, Torridon and Loch Quoich found cloud below them at dawn.
Read the forecast check -
Cadair Idris
Forecast 21 hours ahead
Saved forecast map Cadair Idris stayed inside the area in 11 of our 12 updates. Photos from Tyrrau Mawr, other reports and satellite images all point to a cloud inversion across Eryri.
Read the forecast check
How we check a forecast
For each check, we compare the forecast saved before the event with dated photographs or accounts from people who were there. We check the place and time, show how the forecast changed, and link to the original evidence.
Each check explains whether the match covers the wider area or a particular viewpoint, including anything the evidence can’t confirm. If we revisit saved forecasts using today’s method, we label it as a replay.
Our weather data comes from the Met Office via Open-Meteo. Forecast cloud heights are estimates; photographs can show a sea of cloud, but can’t measure its exact height.
How our cloud inversion forecast worksRead the record fairly
What this archive does not prove
Good evidence includes the boundary of the claim. These limits apply across the archive.
- Possible, Likely and Very likely are model bands, not calibrated percentage probabilities.
- Forecast areas are regional planning guidance, not promises for every summit or valley.
- Photographs confirm visible conditions but are not instrumented cloud-height measurements.
- A modelled inversion boundary is not automatically the observed cloud top.
- Selected positive cases alone cannot establish an overall success rate.
- A mature record should also include false alarms, misses and uncertain outcomes as evidence grows.
Evidence into action
Use the record, then check the newest forecast
Forecast checks show how earlier signals behaved. Your decision should still use the latest inversion window, cloud-layer heights, wind and mountain conditions.