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Maps

4 subjects and 24 maps, each drawn from model runs we download and store ourselves.

About these maps

One map to a page — they share a coastline, and drawing it once per page is most of why they are no longer one long scroll. Each card opens the map its picture shows; the names in a card are that subject's other maps. On every map, the run it was drawn from and how to read it are behind the map's own ⓘ.

Where the models disagree

Unique maps which illustrate the spread: each one draws multiple models at once.

Where the models disagree

These five draw several models on one map, from the same runs. Three shade how far apart the models are: on temperature, on rain totals, and on the 500 mb pattern. Coverage counts how many of them put rain down, and Tracks draws each model's own lows on one frame. A model viewer usually shows one model at a time, which is what most of the maps under All maps by type do.

The pictures are samples of one past run; open a map for today's.

How the forecast changed

One model against its own earlier runs: what the newest run changed.

How the forecast changed

These four set one model against its own earlier runs, so what moves is the forecast rather than the weather. Evolution steps through every stored run's picture of one moment; 24h Change shades where the newest run is warmer or cooler, or has deepened or filled the pressure, against the run a day before.

The pictures are samples of one past run; open a map for today's.

All maps by type

The pictures above are samples, not today's maps — open one for the live version. Every map here is drawn from model output we store ourselves, based on data and products of NOAA, the European Centre for Medium-Range Weather Forecasts (ECMWF), Environment and Climate Change Canada and the Copernicus Climate Change Service, and each map's page names the ones it draws. The per-city read of the same day, and the written discussion of it, is on the national page.

Sources and licences
  • NOAA: GFS and AIGFS, from NOAA's NOMADS server. US government data, not subject to copyright (NOAA/NWS terms of use).
  • ECMWF: IFS and AIFS Single, from ECMWF's open data. This service is based on data and products of the European Centre for Medium-Range Weather Forecasts (ECMWF). Source: www.ecmwf.int. This ECMWF data is published under a Creative Commons Attribution 4.0 International (CC BY 4.0). ECMWF does not accept any liability whatsoever for any error or omission in the data, their availability, or for any loss or damage arising from their use.
  • Environment and Climate Change Canada: GEM, from the MSC Datamart. Data Source: Environment and Climate Change Canada, under its Data Services End-use Licence.
  • Copernicus: ERA5 reanalysis, from NSF NCAR's copy. The PWAT normals are built from it. Contains modified Copernicus Climate Change Service information. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains. Published under CC BY 4.0.

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.