Region Lower 48
United States
Europe
The readings under the map are for the whole map, not only the part shown.
Surface pressure (hPa) and 6-hour averaged precip rate (in/h)
GEM · Run 12Z 4 Oct · +6 h · Valid Sun 18Z 4 Oct
Surface pressure (hPa) and 6-hour averaged precip rate (in/h)
Heaviest 6-hour mean 0.55 in/h, near 30.45N 85.95W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.794 in/h, near 29.55N 81.6W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.6 in/h, near 22.2N 105.15W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.634 in/h, near 29.55N 85.8W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.633 in/h, near 28.5N 92.55W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.574 in/h, near 21.45N 98.4W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.581 in/h, near 21.3N 90.0W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.447 in/h, near 20.85N 105.0W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.691 in/h, near 20.4N 96.6W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.847 in/h, near 21.45N 96.75W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.983 in/h, near 20.1N 121.2W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.903 in/h, near 20.1N 121.05W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.662 in/h, near 20.4N 121.65W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.392 in/h, near 22.95N 83.1W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.835 in/h, near 26.55N 80.4W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.688 in/h, near 21.0N 105.15W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.473 in/h, near 21.9N 124.2W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.34 in/h, near 21.3N 89.7W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.507 in/h, near 21.6N 89.85W · unshaded ground is where the model has under 0.01 in/h falling
Heaviest 6-hour mean 0.473 in/h, near 28.8N 91.95W · unshaded ground is where the model has under 0.01 in/h falling
One GEM run — issued 12Z 4 Oct — played forward 6 hours at a time, from 6 hours out to 120 hours out.
Methodology
Step forward and the pressure pattern moves, and the precipitation under it moves with it: that motion is the weather this run forecasts, not the forecast changing — Forecast Evolution is the film for that. Same chart grammar as the surface analysis: the same reduction, the same 4 hPa interval, the same frame; only the forecast hour varies. Six-hourly to 120 hours. GEM forecasts out to 240 hours; this film stops at 120. The frames past the one shown load on demand. GEM publishes no precipitation rate, so the shading here is the 6-hour mean rate — the run's total precipitation at each frame less the total 6 hours before, over 6 — on the same scale as the instant the other models shade with. A mean over 6 hours is smoother and weaker than an instant, so its heavy bands light less often on the same weather; and because no 6-hour bucket ends at the analysis, this film opens at +6 h rather than showing one frame with no rain under it.
This map is drawn from model output we store ourselves, not from anyone's picture of it, and is based on data and products of Environment and Climate Change Canada. The per-city read of the same day — which cities the models are fighting about, and what the discussion makes of it — is on the national page. Every model's full forecast for any of these cities, or anywhere else, is in the beta: request an invite; it's free during the beta.
Sources and licences
- Environment and Climate Change Canada: GEM, from the MSC Datamart. Data Source: Environment and Climate Change Canada, under its Data Services End-use Licence.
What we change: each field is cropped to the frame these maps share when we download it, and each map then smooths, contours, differences or ranks those numbers as its Methodology says. These are our maps of the providers' numbers, not their products, and none of them has reviewed or endorsed this site.
Coastlines, borders, lakes and place names: Natural Earth, public domain.