Parcel Selections


All parcels are lifted dry adiabatically to their respective lifing condensation level (LCL), and then parcel ascent continues moist adiabatically to the level of free convection (LFC). The "MU" parcel trace is plotted on the skewT diagram as a dashed line sloping up to the left for the dry adiabatic ascent, and a dashed curve sloping up to the left for the moist adiabatic ascent. The effects of water loading and ice processes are not included.

Surface Parcel - begin with the surface station pressure, temperature, and mixing ratio.

Mixed Layer - begin with the surface station pressure and the average temperature and mixing ratio in the lowest 100 mb of the sounding.

FCST Surface - an estimate of the afternoon maximum temperature is combined with the mean mixing ratio in the lowest 100 mb of the sounding. The afternoon temperature is derived from taking the parcel at 850 mb dry adiabatically to the ground, and then adding a 2 C superadiabatic "contact" layer.

MU - This parcel is identified by calculating equivalent potential temperature for each level in the lowest 300 mb of the sounding. The parcel with the largest equivalent potential temperature is designated as the "most unstable". The maximum equivalent potential temperature value can also be viewed in the "Theta E vs Height" inset graphic (below the hodograph plot).