Objectives
The goal of this module is to teach the novice forecaster to effectively use the skew-T/log-P diagram. After completing the module, they should be able to read and interpret a sounding plotted on a skew-T/log P diagram and apply that information to a weather forecast.
Specific objectives include the following:
Given a skew-T/log-P diagram, identify and describe the various lines.
Given a sounding plotted on a skew-T/log-P diagram, read the following properties for a given level:
- Temperature
- Dewpoint
- Mixing ratio
- Saturation mixing ratio
- Wind speed
- Wind direction
- Dewpoint depression
- Potential temperature (theta)
- Equivalent temperature (Te)
- Equivalent potential temperature (theta-e)
- Wet-bulb temperature (Tw)
- Wet-bulb potential temperature (theta-w)
- Saturation vapor pressure (es)
- Vapor pressure (e)
- Convective temperature (Tc)
Given a sounding plotted on a skew-T/log-P diagram, calculate the following properties at a given level:
- Relative humidity (RH)
- Virtual temperature (Tv)
Given a sounding plotted on a skew-T/log-P diagram, determine the following levels:
- Lifting condensation level (LCL)
- Convective condensation level (CCL)
- Level of free convection (LFC)
- Freezing level
- Wet-bulb zero level
- Mixing condensation level (MCL)
- Tropopause
- Equilibrium level (EL)
- Maximum parcel level (MPL)
Given a sounding plotted on a skew-T/log-P diagram, determine the following stability indices and use them to assess the potential for severe weather:
- Lifted index (LI)
- Showalter stability index (SSI)
- K index (KI)
- Total Totals index (TT)
- Severe Weather Threat (SWEAT) index
Describe how CAPE and CIN are determined.
Comparing 2 soundings, determine which has the larger values of CAPE and CIN.
List and describe the different types of stability and identify them in a sounding plotted on a skew-T diagram.
List and describe the different types of lapse rates.
Given a sounding plotted on a skew-T/log-P diagram, characterize the lapse rate of each segment of the sounding.
List and describe processes that alter stability and give examples of common cases where this occurs.
Given a suitable synoptic environment and a sounding plotted on a skew-T/log-P diagram, interpret the sounding with regard to the following forecast problems:
- Airmass Thunderstorms
- Severe thunderstorms
- Convective wind gusts and microbursts
- Hail
- Heavy Precipitation
- Precipitation type
- Maximum temperature
- Thermal Turbulence
- Icing