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MRMS gridded radar products

Available since v0.15.0 as noaa:mrms. Multi-Radar Multi-Sensor merges every NEXRAD radar with other sensors onto one fixed CONUS grid every two minutes. Files are gzipped GRIB2 in the anonymous noaa-mrms-pds bucket, laid out as CONUS/<PRODUCT>/<YYYYMMDD>/MRMS_<PRODUCT>_<YYYYMMDD>-<HHMMSS>.grib2.gz. No AWS credentials or SDK are needed.

Require product and both timestamps. product is the exact directory name from the table below, matched case-sensitively; a near-miss in case is rejected with the intended name. Unknown parameters, text/geographic constraints, and variables are rejected: each file is one whole CONUS grid that the server cannot crop, and the product is the variable. Only the CONUS domain is served; the bucket's ALASKA, CARIB, GUAM, and HAWAII domains, its 5 km CONUS grids, and its ProbSevere feeds are out of scope.

The adapter lists one CONUS/<PRODUCT>/<YYYYMMDD>/ prefix per touched day, follows S3 continuation tokens, and selects files whose stamps fall in the inclusive UTC query interval. A query spans at most one day: a day of one product is 720 files and, for reflectivity, more than a gigabyte. Split longer intervals, and prefer the minutes around an event. Use --dry-run to see the count and total size before downloading. Stamps are usually on even minutes, but many products carry the merge second (-200039), so select by window rather than by an exact stamp. The archive begins on 2020-10-14; earlier windows are rejected before any request.

For example, fetch the one rotation-track file stamped 20:00:00 UTC on 2024-05-06 (about 95 kB):

uv run usdata fetch noaa:mrms -p product=RotationTrackML30min_00.50 \
  --start 2024-05-06T20:00:00Z --end 2024-05-06T20:00:00Z

Supported products

Sizes are the range observed across 2024-05-06, a day with severe weather over the Plains; quiet days are smaller. Grids are 0.01° (3,500 × 7,000 points) except the rotation tracks, which are 0.005° (7,000 × 14,000 points).

Product Meaning Units File size Day
RotationTrack30min_00.50 30-minute maximum low-level azimuthal shear 0.001 s⁻¹ 131–445 kB 179 MB
RotationTrack60min_00.50 60-minute maximum low-level azimuthal shear 0.001 s⁻¹ 206–615 kB 260 MB
RotationTrack120min_00.50 2-hour maximum low-level azimuthal shear, hourly files 0.001 s⁻¹ 328–867 kB 25 MB
RotationTrackML30min_00.50 30-minute maximum mid-level azimuthal shear 0.001 s⁻¹ 35–174 kB 52 MB
RotationTrackML60min_00.50 60-minute maximum mid-level azimuthal shear 0.001 s⁻¹ 57–265 kB 81 MB
RotationTrackML120min_00.50 2-hour maximum mid-level azimuthal shear, hourly files 0.001 s⁻¹ 102–405 kB 8 MB
MergedReflectivityQCComposite_00.50 quality-controlled composite reflectivity dBZ 1.5–2.4 MB 1.3 GB
MergedReflectivityComposite_00.50 composite reflectivity without quality control dBZ 7.2–9.8 MB 5.8 GB
ReflectivityAtLowestAltitude_00.50 reflectivity at the lowest altitude with data dBZ 1.1–1.7 MB 925 MB
MergedBaseReflectivityQC_00.50 quality-controlled base reflectivity dBZ 1.1–1.9 MB 1.0 GB
MESH_00.50 maximum estimated size of hail mm 32–60 kB 28 MB
MESH_Max_30min_00.50 30-minute maximum estimated hail size mm 36–106 kB 40 MB
MESH_Max_60min_00.50 60-minute maximum estimated hail size mm 41–146 kB 50 MB
VIL_00.50 vertically integrated liquid kg m⁻² 440–857 kB 444 MB
VIL_Density_00.50 vertically integrated liquid density g m⁻³ 209–355 kB 185 MB
EchoTop_18_00.50 18 dBZ echo top height km 773 kB–1.6 MB 719 MB
EchoTop_30_00.50 30 dBZ echo top height km 199–550 kB 191 MB
EchoTop_50_00.50 50 dBZ echo top height km 37–59 kB 30 MB
PrecipRate_00.00 radar precipitation rate mm h⁻¹ 679 kB–1.1 MB 564 MB
LightningProbabilityNext30minGrid_scale_1 probability of lightning in the next 30 minutes % 19–57 kB 21 MB

Rotation tracks accumulate the maximum azimuthal shear over the trailing window, so a 30-minute file at 20:30 covers 20:00 to 20:30; the ML variants use the 3–6 km mid-level layer that tornado research usually pairs with the low-level track. The 00.50 and 00.00 suffixes are the product's nominal height in kilometres, part of the directory name. The bucket holds about 240 CONUS product directories; extending the allowlist is a follow-up once a use case needs another product.

Reading grids

Files are opened with the grib extra, through open() or open_grib2(); see readers and their limits. ecCodes has no parameter tables for MRMS's local GRIB discipline, so the reader names the data variable from the product segment of the asset id, which is why asset ids keep the exact upstream filename. Values are stored with the source's sentinels: -999 marks no coverage and -99 marks no data within coverage in the files probed, and neither is a GRIB missing value, so mask them yourself before taking statistics. Files are gzipped; the reader decompresses in memory and the cached bytes stay as published. Without the extra, use fetched.path with any GRIB2 decoder after decompressing.

Memory for large grids

Readers load the whole decoded scene, volume, or field into memory before returning. A 0.005° MRMS grid is 98 million points and peaks near 1.2 GB; a GOES scene and a radar volume can expand to hundreds of megabytes. Select sweeps, coarser products, or shorter windows, or open item.path with a chunked backend. See readers.

Archive coverage

Listing the product directories with a / delimiter found the first day 20201014 for rotation tracks, composite reflectivity, and MESH; the catalog's start records that day. Not every product has every two-minute file: on 2024-05-06, MergedBaseReflectivityQC_00.50 and PrecipRate_00.00 each had 719 files and the 2-hour rotation tracks are written hourly. The NODD registry documents public cloud access and the MRMS product guide describes each product's algorithm, units, and grid.

See the service research notes for dated upstream probes.

Metadata sources

Every value in the catalog entry's resolution, cadence, citation, terms, variables, and limits comes from one of these pages. A field the agency does not publish is left empty rather than estimated.

  • Updates, citation, and terms: the NODD registry entry ("Data is delivered in real-time with a 2-minute update cycle") and the NOAA Open Data Dissemination statement it quotes.
  • Resolution and variables: the MRMS product guide and the product table above; the registry lists exactly the products this adapter supports, with their units.
  • Longest query window: MAX_WINDOW in usdata.providers.noaa.mrms.
  • Latency is empty beyond the real-time claim already in the update cycle.

All NOAA datasets.

Reference

noaa:mrms · Released · Included since usdata 0.15. Multi-Radar Multi-Sensor (MRMS).

At a glance

Parameters

Pass these as --param name=value to the CLI, as params: entries in a manifest, or as keyword arguments to build_query.

Parameter Meaning
product Required product directory name, for example RotationTrackML30min_00.50; see the dataset guide for the supported list.

Variables

Variable Units Meaning
RotationTrack30min_00.50 0.001 s-1 30-minute maximum low-level azimuthal shear
RotationTrack60min_00.50 0.001 s-1 60-minute maximum low-level azimuthal shear
RotationTrack120min_00.50 0.001 s-1 2-hour maximum low-level azimuthal shear, hourly files
RotationTrackML30min_00.50 0.001 s-1 30-minute maximum mid-level azimuthal shear
RotationTrackML60min_00.50 0.001 s-1 60-minute maximum mid-level azimuthal shear
RotationTrackML120min_00.50 0.001 s-1 2-hour maximum mid-level azimuthal shear, hourly files
MergedReflectivityQCComposite_00.50 dBZ Quality-controlled composite reflectivity
MergedReflectivityComposite_00.50 dBZ Composite reflectivity without quality control
ReflectivityAtLowestAltitude_00.50 dBZ Reflectivity at the lowest altitude with data
MergedBaseReflectivityQC_00.50 dBZ Quality-controlled base reflectivity
MESH_00.50 mm Maximum estimated size of hail
MESH_Max_30min_00.50 mm 30-minute maximum estimated hail size
MESH_Max_60min_00.50 mm 60-minute maximum estimated hail size
VIL_00.50 kg m-2 Vertically integrated liquid
VIL_Density_00.50 g m-3 Vertically integrated liquid density
EchoTop_18_00.50 km 18 dBZ echo top height
EchoTop_30_00.50 km 30 dBZ echo top height
EchoTop_50_00.50 km 50 dBZ echo top height
PrecipRate_00.00 mm h-1 Radar precipitation rate
LightningProbabilityNext30minGrid_scale_1 % Probability of lightning in the next 30 minutes

Catalog facts

  • Availability: since 0.15
  • Domain: Weather radar
  • Spatial resolution: 0.01 degree CONUS grid (3,500 x 7,000 points); 0.005 degree for rotation tracks
  • Temporal resolution: Two minutes; the two-hour rotation tracks are written hourly
  • Updates: Data is delivered in real-time with a 2-minute update cycle
  • Longest query window: 1 day
  • Terms of use: https://www.noaa.gov/information-technology/open-data-dissemination
  • Citation: NOAA Multi-Radar/Multi-Sensor System (MRMS) was accessed on [date] from https://registry.opendata.aws/noaa-mrms-pds
  • Geographic bounds (WGS84): west -130°, south 20°, east -60°, north 55°
  • Catalog date range: 2020-10-14 to open-ended
  • Coverage varies by station, product, and date; the range above does not guarantee observations.
  • Upstream documentation
  • License: US Government Work (public domain)
  • Transport: s3
  • Adapter: usdata.providers.noaa.mrms:Mrms