Hail Size ForcastingOnce the forecaster has determined that theprobability of hail exists, as previously outlined, the nextlogical question will relate to the size of the hail that maybe anticipated. The following text discusses the methodthat uses the Skew T Log P diagram.The first step in forecasting hail is to determine theconvective condensation level (CCL). This parameteris evaluated on the adiabatic chart by finding the meanand following this saturation, mixing ratio line to itsintersection with the sounding dry-bulb temperaturecurve. Next, the moist adiabat through the CCL is tracedup to the pressure level where the dry-bulb temperatureis -5°C. This pressure level, the dry-bulb temperaturecurve, and the moist adiabat through the CCL form atriangle, outlining a positive area. Figure 5-9 illustratesthis procedure. The horizontal coordinate in figure 5-9is the length of the horizontal side of the triangle indegrees Celsius.The length is measured from themixing ratio in the moist layer of the lowest 150 hPa.pressure at the base of the triangle.25NP0050Figure 5-9.-Example of hail size forecast sounding.5-13