NOAA Graphical Turbulence Guidance Nowcast

GribStream Code: gtgn

Current source note: GribStream serves the NOAA/NCEP NOMADS para GTGN source while NOAA prepares the operational transition. The public GribStream dataset code is gtgn; when NOAA opens the production NOMADS path, customers can keep the same model page and API code.

NOAA schedule: NWS SCN 26-62 schedules GTGN implementation on or about July 28, 2026 at 1200 UTC, with evaluation data available through NOMADS parallel before implementation.

Official references: NWS SCN 26-62 and NOAA NOMADS GTGN parallel data.

Description

GTGN is NOAA/NCEP's Graphical Turbulence Guidance Nowcast. It blends a short-term GTG forecast background with recent turbulence observations to produce a near-real-time analysis for the aviation community.

The dataset is intentionally narrower than HRRR or RAP. It exposes the turbulence field itself, not a full atmospheric model state. For applications that need winds, temperature, humidity, or cloud context, combine gtgn with HRRR, RAP, or DAFS GTG.

On GribStream, gtgn is useful when the operational question is current turbulence analysis rather than a multi-hour deterministic forecast. The selector catalog keeps NOAA's parameter names and altitude levels visible so clients can choose the EDR surfaces that match their route or flight-level workflow.

Detail

• Archive window: Last 5 days
• Official notice: https://www.weather.gov/media/notification/pdf_2026/scn26-62_GTGN_v1.0.pdf
• Key features:
  • 15-minute near-real-time turbulence nowcast analysis for aviation workflows.
  • CONUS 3 km Lambert grid tied to the HRRR/GTG domain.
  • Eddy Dissipation Parameter (EDPARM) selectors across altitude surfaces from near-surface to 50,000 ft.
  • Coordinate and time-based API access for the nowcast, using the same request pattern as other GribStream datasets.
• Resolution: 3 km CONUS Lambert grid, with altitude surfaces every 1,000 ft from near-surface through 50,000 ft in the NOAA product.
• Temporal coverage: Nowcast snapshots every 15 minutes in the GTGN source; GribStream exposes them as horizon 0 analyses.
• Primary uses: Aviation turbulence monitoring, operations dashboards, route review, turbulence report validation, pilot briefing support, and joining nowcast EDR with HRRR, RAP, or DAFS aviation guidance.

Related datasets

• DAFS GTG for HRRR-derived turbulence forecasts
• HRRR for storm-scale atmospheric context
• RAP for hourly aviation and mesoscale context

Parameters