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Météo-France AROME 0.01° forecasts are now on GribStream

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GribStream now supports Météo-France AROME 0.01°: convection-permitting forecasts for France and nearby countries, refreshed every three hours with hourly surface fields through 51 hours.

GribStream now supports Météo-France AROME 0.01° as aromefrance: convection-permitting deterministic guidance for metropolitan France and nearby countries, refreshed every three hours with hourly lead times through 51 hours.

AROME is Météo-France's short-range limited-area forecasting system. Its approximately 1.3 km model mesh is built to represent fine-scale terrain, precipitation, wind, clouds, and deep convection that broader European and global models necessarily smooth.

The first GribStream release focuses on 17 surface and near-surface fields from all eight daily cycles. It pairs familiar weather variables with high-value convective diagnostics, including maximum simulated radar reflectivity factor, surface-based CAPE, accumulated precipitation by hydrometeor type, and synthetic 10.8 µm brightness temperature.

Météo-France AROME 2 meter temperature forecast over France and nearby countries on the 0.01 degree output grid
Météo-France AROME 2 m temperature valid at 07:00 UTC on July 24, 2026, from the 06 UTC cycle. The plot uses all 4,160,519 populated cells in the source field; the dark corners reveal the model's trapezoidal valid footprint inside its rectangular grid envelope.

A Convection-Permitting Forecast For France

Météo-France describes AROME as its 1.3 km model for mainland France and Corsica, providing forecasters with a much more detailed view of small-scale weather from the next few hours to the next few days.

That resolution places AROME in the convection-permitting class. It represents major cumulonimbus clouds and fine terrain effects more directly than models whose grid cells span many kilometers. This matters for localized thunderstorms, Alpine and Pyrenean flow, Mediterranean precipitation, coastal winds, fog, and narrow rain or snow bands.

The public dataset and the atmospheric model use related but distinct grids:

Property AROME-France system aromefrance public product
Horizontal spacing Approximately 1.3 km model mesh Regular 0.01° latitude-longitude output
Vertical structure 90 model levels 17 surface and near-surface fields
Domain Metropolitan France and neighboring countries EURW1S100 envelope: 37.5N-55.4N, 12W-16E
Forecast range Short range Hourly from +0 through +51 hours

The 0.01° label therefore describes the published output grid, not a claim that the atmospheric model itself runs on a uniform 0.01° mesh.

Current AROME Science: 3DEnVar, ALADIN, And Méso-NH

AROME has been operational at Météo-France since 2008. The Météo-France forecast-system overview describes a model assembled through French and international collaboration: its dynamics adapt the ALADIN core to fine scales, while much of its physical parameterization comes from the Méso-NH research model.

The initialization system changed substantially in October 2024. AROME-France now uses operational 3DEnVar data assimilation, replacing the 3D-Var scheme used since 2008. The ACCORD description of the change explains that 3DEnVar uses flow-dependent, ensemble-based background-error covariances. In practical terms, the way an observation influences surrounding model points can adapt to the current weather situation instead of relying on static and horizontally uniform covariances.

A more responsive analysis can improve the starting point, but it does not make an individual deterministic forecast certain. High resolution can sharpen a thunderstorm or precipitation band while still placing it too early, too late, or a few kilometers away.

Eight Forecasts Per Day Through 51 Hours

AROME-France runs every three hours. Unlike systems that reserve their longest horizon for a subset of cycles, the current 0.01° package guide specifies the same hourly 0-51 schedule throughout the day.

Source cycles Lead times Update interval Main role
00, 03, 06, 09, 12, 15, 18, 21 UTC +0 through +51 hours Hourly Fresh short-range regional guidance

This cadence is especially useful when forecast freshness matters. A product can move to a new AROME cycle every three hours without losing the two-day forecast window, while the five-day GribStream archive keeps recent cycles available for comparison, verification, and short backtests.

Surface Weather And Convective Diagnostics

The initial aromefrance inventory contains 17 Météo-France parameter names:

Group Source fields What they describe
Near-surface state T, HU, U, V, P 2 m temperature and humidity, 10 m wind components, and surface pressure
Wind extremes U_RAF, V_RAF Maximum 10 m gust components over the preceding forecast hour
Clouds NEBBAS, NEBMOY, NEBHAU Low, middle, and high cloud cover
Precipitation type EAU, NEIGE, GRAUPEL Rain, snow, and graupel water equivalent accumulated since analysis time
Convection CAPE_INS, RFLCTVT_MAX Surface-based CAPE and maximum simulated radar reflectivity factor
Observation-like diagnostics BT Synthetic brightness temperature for the 10.8 µm infrared channel
Surface geometry ALTITUDE Model terrain altitude, available at lead zero

Forecast-hour precipitation selectors use info = "acc" because each field accumulates from the analysis time. EAU at +6 hours is therefore the total modeled liquid precipitation from hour 0 through hour 6, not an independent fifth-to-sixth-hour amount. Gust components use info = "max" and describe the preceding forecast hour.

RFLCTVT_MAX and BT deserve another distinction. They are diagnostics calculated from the model state so it can be compared with radar-like and satellite-like views. They are not radar measurements or satellite observations. Météo-France publishes RFLCTVT_MAX as a linear reflectivity factor in mm^6/m^3; it is not the separate dBZ reflectivity product.

Where AROME Adds Value

AROME's strongest role is the detailed short range over France:

  • precipitation timing and type for catchments, roads, railways, and mountain operations
  • convective context for outdoor events, aviation, logistics, and weather monitoring
  • localized wind and gust guidance for renewable generation, cranes, ports, and exposed infrastructure
  • temperature, humidity, pressure, and cloud inputs for energy demand, agriculture, and environmental models
  • model-to-observation comparison using simulated reflectivity and infrared brightness temperature

It should sit inside a model hierarchy rather than replace every other source:

  • use aromefrance for high-resolution deterministic guidance over France through 51 hours
  • use DWD ICON-EU for broader European coverage through five days
  • use ICON-2I for 2.2 km regional guidance centered on Italy
  • use DMI HARMONIE DINI for 2 km surface guidance over Northwestern Europe
  • use ECMWF IFS for global context and a longer deterministic range

For decisions sensitive to thunderstorm location, peak gusts, or intense rainfall, add ensemble guidance and current observations. AROME provides one physically consistent high-resolution scenario, not a probability distribution.

Access AROME In GribStream

Use the dataset code aromefrance. The AROME France model page lists every available name, level, and info combination, including each selector's lead-time coverage. Refer to the API documentation for the current request syntax and endpoints.

Open Data With Attribution

Météo-France publishes the AROME 0.01° package under France's Open Licence 2.0. The licence permits free commercial and non-commercial reuse, adaptation, and redistribution, subject to source attribution and the licence's integrity requirements.

GribStream identifies Météo-France as the creator and links back to the official dataset. Applications that republish or redistribute derived AROME information should preserve that attribution.

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