84 lines
3.8 KiB
Markdown
84 lines
3.8 KiB
Markdown
# RRFS (Rapid Refresh Forecast System) Data Assessment
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## Overview
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RRFS is NOAA's next-generation convection-allowing ensemble forecast system, intended to replace HRRR, RAP, NAM-NEST, and HREF. As of March 2026, RRFS is in operational evaluation — the ensemble post-processing products are publicly available on AWS S3, but the full deterministic model output with pressure-level fields is not yet publicly distributed.
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## Data Availability
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### AWS S3 Bucket: `noaa-rrfs-pds`
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Two public prefixes with identical content:
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- `rrfs_a/refs.YYYYMMDD/HH/enspost/` (primary)
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- `rrfs_public/refs.YYYYMMDD/HH/enspost/` (mirror)
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### Run Schedule
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- 4x daily: 00Z, 06Z, 12Z, 18Z
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- Data available ~2 hours after init time
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- Recent data goes back about 10 days before being pruned
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### Available Products (CONUS)
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| Product | File Pattern | Contents | Usefulness for Propagation |
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|---------|-------------|----------|---------------------------|
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| `avrg` | `refs.tHHz.avrg.fNN.conus.grib2` | Ensemble mean | Only APCP (precipitation accumulation). **Not useful** — missing temp, dewpoint, wind, pressure, refractivity profile |
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| `eas` | `refs.tHHz.eas.fNN.conus.grib2` | Exceedance probability | APCP/ASNOW exceedance probabilities. **Not useful** for propagation scoring |
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| `ffri` | `refs.tHHz.ffri.fNN.conus.grib2` | Flash flood risk index | PPFFG exceedance. **Not useful** |
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| `lpmm` | `refs.tHHz.lpmm.fNN.conus.grib2` | Ensemble mean (alternate) | APCP only. Same limitation as `avrg` |
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### Forecast Hours
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- f01 through f07 (1-7 hour forecasts)
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- ~1.5MB per file for ensemble mean CONUS
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### Grid
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- 3km CONUS domain (same as HRRR)
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- Lambert Conformal projection
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- GRIB2 format with standard .idx files
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## Key Finding: RRFS Public Data is NOT Sufficient for Propagation Scoring
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The publicly available RRFS data on S3 contains **only ensemble post-processing products** — primarily precipitation statistics. It does NOT include:
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- Surface temperature (TMP:2m)
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- Dewpoint temperature (DPT:2m)
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- Surface pressure (PRES:surface)
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- Boundary layer height (HPBL)
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- Precipitable water (PWAT)
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- Wind speed/direction (UGRD/VGRD:10m)
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- Cloud cover (TCDC)
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- Pressure-level profiles (TMP/DPT/HGT at 1000-700mb) for refractivity gradient computation
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These fields are essential for propagation scoring (all 9 factors). HRRR provides all of them.
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## RRFS vs HRRR Comparison
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| Feature | HRRR | RRFS (Public) |
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|---------|------|---------------|
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| Resolution | 3km | 3km |
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| Update frequency | Hourly | 4x daily (00/06/12/18Z) |
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| Forecast range | 18h (48h from 00/06/12/18Z) | 7h (from public data) |
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| Surface fields | Full (TMP, DPT, PRES, wind, cloud, precip) | APCP only |
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| Pressure levels | 8 standard levels (1000-700mb) | Not available publicly |
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| Refractivity profile | Derivable from pressure-level T/Td/P | Not possible |
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| S3 bucket | `noaa-hrrr-bdp-pds` | `noaa-rrfs-pds` |
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| Byte-range requests | Yes (.idx files) | Yes (.idx files) |
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| Historical depth | ~2 days on S3 | ~10 days on S3 |
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## Recommendation
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**Continue using HRRR as the primary data source.** RRFS public data is not yet suitable for propagation scoring due to missing atmospheric profile and surface fields.
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Monitor for:
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1. NOAA making full RRFS deterministic output public (likely when RRFS becomes the operational replacement for HRRR)
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2. Additional fields being added to the ensemble post-processing products
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3. NOMADS distribution of full RRFS output (currently returns 403)
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When RRFS full output becomes available, key advantages would be:
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- Ensemble spread information (confidence intervals on propagation scores)
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- Potentially improved boundary layer and moisture forecasts from the FV3 dynamic core
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- Longer forecast horizon for propagation prediction
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## References
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- AWS S3: `s3://noaa-rrfs-pds/`
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- NOAA RRFS: https://gsl.noaa.gov/focus-areas/unified_forecast_system/rrfs
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- NOAA EMC RRFS: https://github.com/NOAA-EMC/rrfs-workflow
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