Climate Forecast System (CFS Pressure)

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.

5-wave geopotential height anomaly isolates planetary-scale wave patterns in the midlatitude flow. It highlights departures from the climatological wave-5 structure, useful for large-scale regime analysis.

• Units: m.

5-wave geopotential height represents the planetary-scale wave-5 component of the flow. It is used in long-range diagnostics to describe large-scale ridge and trough patterns.

• Units: m.

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.

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.

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.

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.

Cloud water mixing ratio is the mass of liquid cloud droplets per mass of air. It describes in‑cloud liquid water content.

• Units: kg/kg.
• Cloud fraction influences surface radiation and temperature.

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.

Cloud water is the total liquid water content (often column‑integrated). It is used to assess cloud water burden.

• Units: kg/m².
• Cloud fraction influences surface radiation and temperature.

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.

Geopotential anomaly is the departure of geopotential from a reference field. It highlights large-scale mass anomalies and flow regime shifts.

• Units: m²/s².

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.

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.

Convective precipitation is water-equivalent accumulation produced by convective processes during the output period. It highlights thunderstorm-driven rainfall.

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

Ozone mixing ratio is the mass of ozone per mass of air. It is used in radiation, chemistry, and upper‑air diagnostics.

• Units: kg/kg.

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.

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

• Units: K.

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.

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.

Stream function is a flow potential whose contours follow non-divergent flow. It is used to visualize rotational components of the wind field.

• Units: m2 s-1.

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

• Units: K.

Total column ozone is the integrated ozone amount through the atmosphere. It affects UV radiation reaching the surface and atmospheric chemistry.

• Units: Dobson.

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.

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

• Units: 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.

Velocity potential represents the divergent component of the wind. It is used with stream function to separate divergent and rotational flow.

• Units: m²/s.

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

• Units: m/s.

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

• Units: Pa/s.

Vertical wind shear measures how wind changes with height. It influences storm organization and aviation turbulence.

• Units: 1/s.