FREEZING RAIN OR SLEETTHE TAU TECHNIQUE - Cys et al., 1996
1. IDENTIFY DEPTH OF WARM LAYER (ABOVE 0OC)
2. IDENTIFY THE MEAN TEMPERATURE OF THE WARM LAYER
3. THEN , FIND COORDINATE ON THE CHART ABOVE, THE YELLOW AREA USUALLY GIVES FREEZING RAIN WHILE THE WHITE AREA GIVES SLEET