Global Ensemble Forecast System Atmosphere (GEFS Atmos)

Convective Available Potential Energy (CAPE) quantifies buoyant energy available to rising air parcels. Larger values generally imply stronger potential updrafts and greater convective intensity.

• Units: J/kg.
• Often used with CIN and lifting mechanisms to assess thunderstorm potential.

Convective Inhibition (CIN) measures the energy barrier that must be overcome to initiate convection. More negative values indicate a stronger cap that can suppress storms.

• Units: J/kg.
• When CIN is weak and CAPE is high, convection is more likely.

Dew point temperature is the temperature at which the air becomes saturated. It is a direct measure of moisture content.

• Units: K.
• When dew point is close to air temperature, fog or low cloud potential increases.

Wind gust is the peak short-duration wind speed. It captures brief, hazardous bursts that can exceed sustained winds.

• Units: m/s.

Geopotential height is the altitude of a pressure surface in the atmosphere. It is the primary field for identifying ridges, troughs, and large‑scale flow patterns.

• Units: gpm.

Storm-relative helicity measures the potential for streamwise vorticity to be ingested by a storm updraft. Higher values suggest a greater likelihood of rotating updrafts.

• Units: m^2/s^2.
• Commonly evaluated in the lowest 1 to 3 km layer.

Ice thickness is the physical thickness of sea or lake ice. It is important for marine navigation and heat exchange.

• Units: m.

Pressure is the atmospheric pressure at the specified level. It is a fundamental mass-field variable for dynamics and thermodynamics.

• Units: Pa.

Pressure reduced to mean sea level is MSLP computed from surface pressure and temperature. It is used to locate highs and lows.

• Units: Pa.

Precipitable water is the total column water vapor from the surface to the top of the atmosphere. It is a key moisture indicator.

• Units: kg/m^2.

Relative humidity describes how close the air is to saturation at the specified level. High values favor cloud formation.

• Units: percent.
• Higher values indicate more atmospheric moisture and greater cloud or precip potential.

Snow depth is the physical thickness of the snowpack. It is distinct from snow water equivalent, which measures water content.

• Units: m.

Volumetric soil moisture is the fraction of soil volume occupied by water. It is commonly used in hydrology and drought monitoring.

• Units: Fraction.
• Soil state affects evapotranspiration and boundary-layer moisture.

Maximum temperature is the highest temperature reached during the output period. It is commonly used for heat stress and daily extremes.

• Units: K.

Minimum temperature is the lowest temperature reached during the output period. It is commonly used for frost and cold-stress assessment.

• Units: K.

Air temperature is the thermal state of the atmosphere at the specified level. It influences density, stability, and energy exchange.

• Units: K.

Soil temperature describes the thermal state of the soil layer. It affects ground heat flux and freeze/thaw processes.

• Units: K.
• Soil state affects evapotranspiration and boundary-layer moisture.

U‑component of wind is the east‑west component of the horizontal wind. Combine with v for speed and direction.

• Units: m/s.
• Combine u and v components to compute speed and direction.

V‑component of wind is the north‑south component of the horizontal wind. Combine with u for speed and direction.

• Units: m/s.
• Combine u and v components to compute speed and direction.

Snow water equivalent (SWE) is the total liquid water stored in the snowpack. It integrates depth and density of existing snow.

• Units: kg/m^2.
• Accumulations represent water-equivalent depth over the output interval; rates describe intensity.