NOAA Global Ensemble Forecast System - Atmospheric Members (GEFS Atmos)

GribStream Code: gefsatmos

Description

The Global Ensemble Forecast System (GEFS) is NOAA's flagship medium-range ensemble, produced by running the GFS 31 times each cycle: 1 control member plus 30 stochastically-perturbed members. Each member carries slightly different initial conditions and model physics, allowing the spread of outcomes to quantify forecast uncertainty.

GEFS Atmos on GribStream exposes every individual member on a 0.25° global grid out to 240 hours (10 days), with four cycles per day (00/06/12/18 UTC). Ensemble mean and spread GRIBs are included for quick aggregate analysis.

This probabilistic data stream is ideal for scenario planning, renewable-energy supply forecasting, aviation routing, hydrological flood risk, severe-weather thresholds, and research into model skill and reliability. By sampling the full member set you can compute exceedance probabilities, percentile envelopes, and ensemble sensitivity metrics in real time.

Detail

Product page: https://www.ncei.noaa.gov/products/weather-climate-models/global-ensemble-forecast
Key Features:
- 31 atmospheric members (30 perturbations + 1 control) plus pre-computed mean & spread files.
- 0.25° (~28 km) global regular latitude/longitude grid.
- Cycles: 00, 06, 12 & 18 UTC.
- Lead times: 0-240 h every 3 h.
- Surface & pressure-level parameters: winds, temperature, humidity, precipitation, MSLP, geopotential, CAPE, etc.
Primary Use Cases: Probabilistic risk assessment, ensemble mean guidance, renewable-energy forecast spread, flight planning, hydrology & flood outlooks, climate-model initialization, and research.

Parameters:

Name	Level	Description	Introduced	Max Horizon
CAPE	surface	Convective Available Potential Energy (J/kg)	2020-10-01T00:00:00Z	240
CAPE	180-0 mb above ground	Convective Available Potential Energy (J/kg)	2020-10-01T00:00:00Z	240
CIN	surface	Convective Inhibition (J/kg)	2020-10-01T00:00:00Z	240
CIN	180-0 mb above ground	Convective Inhibition (J/kg)	2020-10-01T00:00:00Z	240
DPT	2 m above ground	Dew Point Temperature (K)	2020-10-01T00:00:00Z	240
GUST	surface	Wind Speed (Gust) (m/s)	2020-10-01T00:00:00Z	240
HGT	surface	Geopotential Height (gpm)	2020-10-01T00:00:00Z	0
HGT	cloud ceiling	Geopotential Height (gpm)	2025-06-18T12:00:00Z	240
HLCY	3000-0 m above ground	Storm Relative Helicity (m^2/s^2)	2020-10-01T00:00:00Z	240
ICETK	surface	Ice Thickness (m)	2020-10-01T00:00:00Z	240
PRES	surface	Pressure (Pa)	2020-10-01T00:00:00Z	240
PRMSL	mean sea level	Pressure Reduced to MSL (Pa)	2020-10-01T00:00:00Z	240
PWAT	entire atmosphere (considered as a single layer)	Precipitable Water (kg/m^2)	2020-10-01T00:00:00Z	240
RH	2 m above ground	Relative Humidity (%)	2020-10-01T00:00:00Z	240
SNOD	surface	Snow Depth (m)	2020-10-01T00:00:00Z	240
SOILW	0-0.1 m below ground	Volumetric Soil Moisture Content (Fraction)	2020-10-01T00:00:00Z	240
TMAX	2 m above ground	Maximum Temperature (K)	2020-10-01T00:00:00Z	240
TMIN	2 m above ground	Minimum Temperature (K)	2020-10-01T00:00:00Z	240
TMP	2 m above ground	Temperature (K)	2020-10-01T00:00:00Z	240
TSOIL	0-0.1 m below ground	Soil Temperature (K)	2020-10-01T00:00:00Z	240
UGRD	10 m above ground	U-Component of Wind (m/s)	2020-10-01T00:00:00Z	240
VGRD	10 m above ground	V-Component of Wind (m/s)	2020-10-01T00:00:00Z	240
WEASD	surface	Water Equivalent of Accumulated Snow Depth (kg/m^2)	2020-10-01T00:00:00Z	240