NAM CONUS Upper Air

Best (4-layer) lifted index uses parcels from the lowest four model layers to assess stability at 500 hPa. More negative values indicate greater instability.

• Units: K.
• Often used alongside CAPE and CIN in convective forecasting.

Absolute vorticity combines relative vorticity and planetary vorticity from Earth's rotation. It highlights rotation and dynamical forcing in the flow.

• Units: 1/s.

Convective precipitation accumulation represents precipitation produced by the convection scheme during the output period. It isolates convective rainfall from larger-scale precipitation.

• Units: kg/m².
• Useful for identifying convectively driven rainfall contributions.

Surface albedo is the fraction of incoming shortwave radiation reflected by the surface. Higher albedo means less solar energy absorbed and a cooler surface.

• Units: percent.
• Important for snow and ice feedbacks and surface energy balance.

Accumulated precipitation represents the total water-equivalent amount of rain and snow during the output period. It is a primary field for hydrologic impacts and event totals.

• Units: kg/m^2.
• Use with the model time interval to interpret totals and compare to gauges.

Blackadar's mixing length scale is the turbulence length scale used by boundary-layer physics to limit the size of turbulent eddies. It directly affects the exchange coefficients that control momentum, heat, and moisture mixing near the surface and through the planetary boundary layer.

• Units: m.
• This is mainly a model-physics diagnostic rather than a directly observed atmospheric variable.

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.

Drag coefficient represents the aerodynamic resistance between the surface and the atmosphere. It controls surface stress and is used in momentum and heat flux calculations.

• Units: dimensionless.

Categorical indicator of freezing rain occurrence at the surface during the output period.

• Units: flag.
• Useful as a mask for icing or glaze hazards.

Categorical indicator of ice pellet (sleet) occurrence at the surface during the output period.

• Units: flag.
• Use with precipitation fields to gauge intensity.

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.

Plant canopy surface water is liquid water intercepted by vegetation. It represents interception storage and evaporation potential.

• Units: kg/m^2.

Categorical indicator of rain occurrence at the surface during the output period. Useful as a yes/no mask for rain.

• Units: flag.
• Use with accumulation or rate fields for intensity.

Categorical indicator of snow occurrence at the surface during the output period.

• Units: flag.
• Use alongside snowfall/snow-water-equivalent fields.

Downward longwave (thermal) flux represents incoming energy at the surface. It is a key driver of surface heating and cooling.

• Units: W/m^2.
• Shortwave affects surface heating; longwave affects radiative cooling.

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.

Downward radiative flux represents incoming energy at the surface. It is a key driver of surface heating and cooling.

• Units: W/m^2.
• Shortwave affects surface heating; longwave affects radiative cooling.

Geometric vertical velocity (dz/dt) is the vertical speed of air in height coordinates. Positive values indicate rising motion and negative values sinking motion.

• Units: m/s.

Friction velocity (u*) is a measure of near‑surface shear stress. It is commonly used in turbulence, dust, and air‑sea exchange calculations.

• Units: m/s.

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.

Haines Index combines atmospheric stability and dryness to estimate the potential for large fire growth. Higher values indicate a more favorable environment for extreme fire behavior.

• Units: Numeric.
• Typically used in wildfire forecasting and risk monitoring.

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.

Boundary layer height marks the depth of the turbulent surface-influenced layer. It affects mixing, dispersion, and surface fluxes.

• Units: m.

Ice cover is the proportion of the grid cell covered by ice. It is used as a surface-state mask for sea ice and related cryosphere diagnostics.

• Units: Proportion.

Land cover is a land/sea mask where 0 indicates sea and 1 indicates land. It is used to separate land and ocean surface processes.

• Units: Proportion.

Lifted Index compares a lifted parcel's temperature to the environment at 500 hPa. More negative values indicate greater instability and thunderstorm potential.

• Units: K.
• Values near zero indicate neutral stability.

Latent heat net flux represents energy exchange due to evaporation/condensation at the surface. It links moisture and energy budgets.

• Units: W/m^2.

Lightning is a dimensionless model diagnostic in these NOAA mesoscale inventories. Higher values indicate greater modeled lightning or convective electrical activity.

• Units: non-dim.

Maximum relative humidity is the highest RH reached during the period. It can indicate peak cloud or fog potential.

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

Maximum u‑component of wind is the strongest east‑west flow during the period. It helps identify peak wind directions.

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

Maximum v‑component of wind is the strongest north‑south flow during the period.

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

Minimum relative humidity is the lowest RH reached during the period. It is used in fire‑weather and drying assessments.

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

Mean sea level pressure (ETA reduction) is MSLP computed using the ETA model reduction method. It is used for synoptic analysis.

• Units: Pa.

Moisture availability represents how much moisture is available at the surface for evaporation. It is used in land-surface and fire-weather diagnostics.

• Units: percent.

Parcel lifted index compares a lifted parcel temperature to the environment at 500 hPa. More negative values indicate greater instability and thunderstorm potential.

• Units: K.
• More negative values indicate greater instability.

Soil porosity is the fraction of soil volume that is pore space. It governs storage and drainage capacity.

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

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.

Composite reflectivity is the maximum reflectivity in the column. It is a standard radar‑style field for identifying convective cores and precipitation intensity.

• Units: dBZ.

Reflectivity is a radar‑style measure of hydrometeor concentration at a given level. Higher values generally correspond to heavier precipitation.

• Units: dBZ.

Echo top height is the altitude of the highest reflectivity in the column. It is a proxy for storm depth and convective vigor.

• Units: m.

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.

Number of soil layers is a static model metadata field describing the soil discretization.

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

Surface roughness length is the effective height of surface obstacles that control drag. It strongly influences near-surface wind, turbulence, and exchange fluxes.

• Units: m.

Sensible heat net flux is turbulent heat exchange driven by temperature differences. It affects near‑surface temperature and stability.

• Units: W/m^2.

Direct evaporation cease (soil moisture) is the threshold below which bare-soil evaporation is shut off in the land-surface model.

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

Transpiration stress-onset (soil moisture) is the threshold at which plants begin to experience moisture stress in the land-surface model.

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

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

• Units: m.

Snow cover is the fraction of the grid cell covered by snow. It helps interpret albedo, runoff timing, and surface energy balance.

• Units: percent.

Liquid volumetric soil moisture (non-frozen) is the liquid portion of soil water expressed as a proportion of soil volume, excluding soil ice.

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

Soil moisture content is the amount of water stored in the soil layer or column represented by the product.

• Units: kg/m^2.
• Soil state affects evapotranspiration and boundary-layer moisture.

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.

Soil type class used by the land-surface model. It controls infiltration, drainage, and heat/moisture storage, and strongly affects runoff and evapotranspiration.

• Units: code.

Specific humidity is the mass of water vapor per mass of air at the specified level. It is central to moisture transport.

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

Total cloud cover is the fraction of the grid cell covered by clouds at any level. It influences radiation, temperature, and visibility.

• Units: percent.
• Cloud fraction influences surface radiation and temperature.

Turbulent kinetic energy represents the intensity of turbulent motions. Higher values indicate stronger mixing and potential turbulence.

• Units: m^2/s^2.

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.

Upward longwave (thermal) flux represents outgoing energy at the surface. It is a key driver of surface heating and cooling.

• Units: W/m^2.
• Shortwave affects surface heating; longwave affects radiative cooling.

Upward radiative flux represents outgoing energy at the surface. It is a key driver of surface heating and cooling.

• Units: W/m^2.
• Shortwave affects surface heating; longwave affects radiative cooling.

Vegetation fraction is the portion of the grid cell covered by vegetation. It affects albedo, roughness, and evapotranspiration.

• Units: percent.

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.

Categorical land-use/vegetation class. It is used to set roughness, albedo, canopy properties, and other surface-exchange parameters.

• Units: code.

Horizontal visibility at the surface. Lower values indicate reduced visibility due to fog, precipitation, or aerosols.

• Units: m.

Ventilation rate combines mixing depth and transport wind to estimate the atmosphere's ability to disperse smoke and pollutants.

• Units: m^2/s.

Vertical u-component shear describes how the east-west wind component changes with height.

• Units: 1/s.

Vertical v-component shear describes how the north-south wind component changes with height.

• Units: 1/s.

Vertical velocity in pressure coordinates (omega). Negative values indicate upward motion (rising air); positive values indicate subsidence.

• Units: Pa/s.

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.

Wilting point is the soil moisture threshold below which plants can no longer extract water. It is used in drought and vegetation stress diagnostics.

• Units: Proportion.