Rapid Refresh Forecast System 2D Fields

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.

Aerosol emission flux represents the rate at which aerosols are emitted into the atmosphere from the surface. It reflects source strength from dust, smoke, and other particulates.

• Units: kg/(m^2 s).
• Higher values indicate stronger aerosol source activity.

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.

Aerosol optical thickness represents the column-integrated attenuation of solar radiation by aerosols. Larger values indicate hazier conditions and reduced surface sunlight.

• Units: dimensionless.
• Useful for visibility, air quality, and solar energy assessments.

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.

Accumulated snow depth is the total depth of snow on the ground over the period. It is a physical depth, not water equivalent.

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

Brightness Temperature (K).

Critical Angle (degree).

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.

Ceiling height is the altitude of the lowest cloud base that covers a significant portion of the sky. It is a key aviation and surface-visibility metric.

• Units: m.

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.

Column-integrated soil moisture is the vertically integrated amount of water stored in the soil column.

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

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

• Units: kg/m^2.

Column-integrated mass density is the total mass per unit area through the vertical column for the specified species. It summarizes column burden and is useful for transport diagnostics.

• Units: kg/m^2.

Percent frozen precipitation indicates the fraction of total precipitation that is falling in frozen form. It helps distinguish mixed-phase and winter precipitation impacts.

• Units: percent.
• Higher values indicate a larger frozen contribution to the total precipitation.

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.

Clear‑sky downward shortwave flux is broadband solar energy at the surface without cloud effects.

• Units: W m-2.

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

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

Downdraft Convective Available Potential Energy (J/kg).

Dew point depression is the difference between air temperature and dew point. Small values indicate near‑saturation.

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

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.

Effective Storm Relative Helicity (m2 s-2).

Equilibrium Level Melting Potential (K).

East longitude gives the longitude position of the grid point in degrees east. It is a static geographic coordinate field.

• Units: degrees.

Fire Radiative Power (W).

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.

Freezing rain accumulation is the water-equivalent amount of freezing rain during the period. It relates directly to ice accretion risk.

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

Freezing rain accumulation is the water-equivalent amount of freezing rain during the period. It relates directly to ice accretion risk.

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

Ground heat flux is the conductive heat exchange between the surface and the subsurface. It is a key term in the surface energy balance.

• Units: W/m^2.

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

• Units: m/s.

Hail represents hail size as a length measure. Larger values indicate more severe hail potential.

• Units: m.
• Use it with convective parameters and reflectivity fields to assess severe-storm potential.

High cloud cover is the fraction of the grid cell covered by clouds in the upper troposphere. It affects longwave radiation and aviation.

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

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.

Mass Density Height (m).

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.

Ice growth rate represents the rate of sea-ice thickness increase. It reflects freezing conditions at the surface and in the upper ocean.

• Units: kg/m^2.

Leaf Area Index (dimensionless).

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.

Layer thickness is the vertical distance between the bounds of a layer. It helps interpret thermodynamic and lifted-layer diagnostics.

• Units: m.

Low cloud cover is the fraction of the grid cell covered by low clouds. It strongly affects visibility, fog potential, and surface temperatures.

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

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.

Mass-Point Land Mask (flag).

Velocity-Point Land Mask (flag).

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

• Units: non-dim.

Lightning Strike Density (flashes km-2).

Mass density (concentration) represents mass per unit volume of the named species or medium. It is used for concentration and transport analyses.

• Units: kg/m^3.

Hourly maximum downward vertical velocity in the lowest 400 hPa highlights the strongest subsidence within the lower troposphere during the hour.

• Units: m/s.

Hourly maximum simulated reflectivity at 1 km AGL captures the strongest modeled reflectivity near the surface. It is used to identify peak convective intensity and heavy precipitation cores.

• Units: dBZ.

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.

Hourly maximum upward vertical velocity in the lowest 400 hPa highlights the strongest updrafts within the lower troposphere during the hour.

• Units: m/s.

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.

Mid-level cloud cover is the fraction of the grid cell covered by clouds in the middle troposphere. It influences both shortwave and longwave radiation.

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

Moisture convergence is the horizontal convergence of water vapor transport. Areas of convergence favor rising motion and precipitation development.

• Units: kg/(m^2 s).

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.

Hourly minimum updraft helicity is the lowest helicity value during the hour. It provides a lower bound on rotating updraft potential.

• Units: m2/s2.

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.

Maximum snow albedo is the highest reflectivity of the snow surface during the period. Higher values indicate fresher, brighter snow.

• Units: percent.
• Accumulations represent water-equivalent depth over the output interval; rates describe intensity.

Hourly maximum updraft helicity (2–5 km AGL) highlights the strongest rotating updrafts during the hour.

• Units: m2/s2.

North latitude gives the latitude position of the grid point in degrees north. It is a static geographic coordinate field.

• Units: degrees.

Potential evaporation is the amount of water that could evaporate if sufficient moisture were available. It reflects atmospheric demand.

• Units: kg/m^2.

Potential evaporation rate is the potential latent heat flux for evaporation under an assumed unlimited water supply.

• Units: W/m^2.

Pressure of the level from which the parcel was lifted indicates the parcel source level used for stability indices. It helps interpret lifted index and CAPE products.

• Units: Pa.

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.

Potential temperature is the temperature a parcel would have if brought dry‑adiabatically to a reference pressure. It is used for stability.

• Units: K.

Precipitation rate is the total intensity of precipitation over the period. It combines convective and stratiform contributions.

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

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

• 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.

Quantitative Precipitation Forecast Average Recurrence Interval (year).

Quantitative Precipitation Forecast Relative to Flash Flood Guidance (%).

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.

Relative vorticity measures local rotation of the horizontal wind field. Positive values indicate cyclonic rotation and negative values anticyclonic rotation.

• Units: 1/s.

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.

Relative humidity with respect to precipitable water is a column‑scale moisture indicator based on total water vapor content.

• 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.

Minimum stomatal resistance is a vegetation parameter controlling transpiration efficiency. Lower values allow stronger evapotranspiration under favorable conditions.

• Units: s m-1.

Snow sublimation is the loss of snow directly to water vapor. It reduces snowpack without melting and can be important in dry, windy conditions.

• Units: kg/m².
• Accumulations represent water-equivalent depth over the output interval; rates describe intensity.

Simulated Brightness Temperature ABI Channel 10 (K).

Simulated Brightness Temperature ABI Channel 11 (K).

Simulated Brightness Temperature ABI Channel 12 (K).

Simulated Brightness Temperature ABI Channel 13 (K).

Simulated Brightness Temperature ABI Channel 14 (K).

Simulated Brightness Temperature ABI Channel 15 (K).

Simulated Brightness Temperature ABI Channel 16 (K).

Simulated Brightness Temperature ABI Channel 7 (K).

Simulated Brightness Temperature ABI Channel 8 (K).

Simulated Brightness Temperature ABI Channel 9 (K).

Simulated Brightness Temperature ABI Channel 10 (K).

Simulated Brightness Temperature ABI Channel 11 (K).

Simulated Brightness Temperature ABI Channel 12 (K).

Simulated Brightness Temperature ABI Channel 13 (K).

Simulated Brightness Temperature ABI Channel 14 (K).

Simulated Brightness Temperature ABI Channel 15 (K).

Simulated Brightness Temperature ABI Channel 16 (K).

Simulated Brightness Temperature ABI Channel 8 (K).

Simulated Brightness Temperature ABI Channel 9 (K).

Snow Density (kg m-3).

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.

Surface exchange coefficient is the bulk transfer coefficient used to compute turbulent heat and moisture fluxes. It depends on stability and roughness.

• Units: dimensionless.

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 phase change heat flux is the energy used for melting or freezing snow. It links radiation and snowpack evolution.

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

Snow melt represents water released by melting snowpack during the period. It is a key driver of runoff and flooding.

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

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.

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.

Storm surface runoff represents overland flow generated by rainfall or snowmelt. It responds quickly to heavy precipitation.

• Units: kg/m^2.

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.

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.

Total snowfall probability gives the chance of measurable snowfall during the period.

• Units: percent.
• Accumulations represent water-equivalent depth over the output interval; rates describe intensity.

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 Effective Inflow Layer Wind (m/s).

U-Component of Effective Shear (m/s).

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.

Updraft helicity is the vertical integral of rotating updraft strength. It is used to identify supercell potential.

• Units: m2/s2.

U‑component of storm motion is the east‑west component of the storm translation vector.

• Units: m/s.

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.

Visible beam downward solar flux is the direct visible sunlight at the surface. It is important for illumination and solar energy.

• Units: W m-2.

Visible diffuse downward solar flux is the scattered visible light at the surface. It increases under clouds or aerosol loading.

• Units: W m-2.

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

• Units: percent.

Maximum Vegetation Fraction (%).

Minimum Vegetation Fraction (%).

V-Component of Effective Inflow Layer Wind (m/s).

V-Component of Effective Shear (m/s).

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.

Vertically‑integrated liquid water is the total column liquid water content. It is used as a proxy for precipitation intensity and hail potential.

• Units: kg/m^2.

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.

V-component storm motion represents the north-south component of storm motion. Positive values indicate motion toward the north.

• Units: m/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 wind shear measures how wind changes with height. It influences storm organization and aviation turbulence.

• Units: 1/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.

Wildfire Potential (dimensionless).

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.

Wind speed is the magnitude of the horizontal wind at the specified level. It is used for transport, mixing, and hazards.

• Units: m/s.

Water temperature is the thermal state of the ocean or lake surface. It influences air-sea fluxes and marine hazards.

• Units: K.