What this is
Twice a day, after ECMWF's 00 and 12 UTC forecasts reach
ECMWF Open Data,
Claude (an AI model) scans the world for interesting weather and picks about fifteen highlights. It writes a short
explanation for each and sets up one or more animated scenes from the forecast. People using the companion iPhone
app can also request an event; those appear under Requested for two days.
This is model guidance, chosen and written automatically, not an official forecast or warning. For those, see
your National Meteorological Service.
Choosing what to watch
- Highlights (left, or across the top on a phone): pick an event. Each says where it is and how many scenes it has.
- Scenes (the numbered tabs above the map): each scene shows a different side of the event, such as pressure and
upper-air pattern, then gusts, then the ensemble's view. Work through them in order.
- The panel below or beside the map explains what's happening, why it's interesting, and where the information came from.
Playing the forecast
- ▶ / ❚❚ plays or pauses; drag the slider to move through time. Under the time is the forecast's lead time and
the model run it comes from.
- 2× changes the speed: ½×, 1×, 2× or 4×. 1× plays one frame a second, and frames are usually 3 hours
apart, so the starting speed of 2× shows 6 forecast hours a second. Your choice is remembered.
- Captions on the map point out what to look for as the forecast unfolds.
Moving around the map
- Drag to pan; scroll, pinch or use + and − to zoom.
- Target button: back to the whole scene.
- Full screen button: the map and timeline fill the screen (Esc or the same button to return).
- Layers button: dark, light or satellite background (satellite imagery: NASA Blue Marble).
- Tap or click anywhere on the map for the value at that point.
Reading the map
- Colours: the field named in the key at the top left, such as wind gusts, rain or temperature.
- Lines: isobars (mean sea level pressure, every 4 hPa) or 500 hPa height, with values along them.
- H and L: centres of high and low pressure, with their central pressure.
- Moving streaks: wind direction and speed.
- "Chance of …" layers come from the ECMWF ensemble (IFS ENS): the percentage of its 51 forecasts showing the event.
Units and times
Units follow your device's region: for example °F, mph and inches in the US; °C, mph and mm in the UK; °C, km/h and mm
in most other places. Change any of them with the units button at the top. Figures in the text change to match.
Times are shown in UTC unless you change Time zone in the same menu to your own zone, shown by its usual name
such as NZDT, CET or EDT. Times in the text that include a date change too. Model
runs keep their UTC names (for example "00 UTC run"), as do times written without a date. Your choices are remembered
in this browser.
Sharing and saving
- Share creates a link to exactly what you're looking at: the highlight, the scene, the moment, the map style
and your view. Whoever opens it sees their own units and time zone. Links keep working for a week after a highlight is replaced.
- Video makes an MP4 of the current scene from start to end at your chosen speed, square, portrait or
landscape, with the title, time, key, caption and ECMWF credit drawn in. Use it for social media. It's made in
your browser and takes a few seconds to a minute. It needs a recent browser; where it isn't supported the button doesn't appear.
- Save downloads one web page file, either this highlight or all current ones, that plays with no
connection. Open it in a browser on a computer. Satellite backgrounds still need the internet.
Data
Forecasts: ECMWF IFS (HRES and ENS) from ECMWF Open Data, © ECMWF, CC BY 4.0, regridded and converted. Map outlines:
Natural Earth. Satellite imagery: NASA Blue Marble via GIBS. New highlights appear at about 04 and 16 UTC.