2-45,  each  storm  is  assigned  a  unique  alphanumeric identifier. The small green triangles that are not filled in indicate the probability of hail of any size within that particular  storm.  The  small  green  filled  triangles indicate the probability of hail equal to or greater than 3/4 of an inch. The numbers inside the larger green triangles indicate maximum expected hail size to the nearest whole inch. In any case, the Hail Index product quickly indicates the possibility of severe weather in the radar coverage area. Hail is a volumetric product, therefore, it is only available at the end of a volume scan. It requires input from several sources, and contamination at any level results in a loss of the product. While the hail product is nice to have, it should be routinely verified using VIL and VEL. Reflectivity Cross-Section (RCS) Product Cross sections provide a unique perspective of the atmosphere. They create an illusion that places you, the operator, into the heart of a target. This allows you to view meteorological targets, such as mesocyclones, from  the  inside.  Cross-section  products  can  be  built from  any  of  three  radar  moments  (reflectivity, velocity, and spectrum width) and are primarily used to examine vertical storm structure. All cross-section products operate on essentially the same principle. That  is,  they  allow  a  vertical  depiction  of  the atmosphere by compiling base data vertically, along a user-defined  direction.  Data  from  a  cross-section product is presented in a range (up to 124 nmi) versus height (up to 70,000 feet) format. The Reflectivity Cross-Section (RCS) product is helpful  even  during  nonconvective  events.  The  depth of moist layers can be determined by the vertical extent (thickness) of scatterers. When cross sections are cut across  frontal  boundaries,  frontal  slope  can  be determined.  For  observing  purposes,  RCS  is  a  good tool for measuring cloud bases and tops, and inversion boundaries. Clouds generally appear as well-defined layers, with a significant decrease in energy (dBZs) at the cloud‘s edge. Of course, RSC is very useful when evaluating severe weather potential. It permits three- dimensional analysis of storm dynamics and lets you determine  the  extensiveness  or  depth  of  a  given feature. RCS is also an excellent product for locating WERs, BWERs, and maximum reflectivity cores. Figure 2-46 is an example of the RCS product. The selection and placement of the cross section is extremely important. Even slight deviations often result  in  misanalysis  of  anticipated  features  (hooks, BWER, etc.). Also be aware that targets displayed by RCS are not always meteorological, but may be the result of birds, insects, etc. Velocity Cross-Section (VCS) Product When it comes to storm interrogation, no analysis is complete without a thorough look at velocity data. The Velocity Cross-Section (VCS) product provides a vertical cross section of velocity data. It is available in two  different  modes;  clear-air  and  precipitation. In clear-air mode (mode A), the Vertical Cross- Section  (VCS)  product  can  determine  the  existence and  depth  of  turbulent  layers  and  determine  the intensity of wind shear. Boundaries and frontal slopes are  evident  by  significant  changes  in  wind  speed  or direction. These features are often more visible here rather than on an RCS product. In precipitation mode (mode B), the existence, strength, and vertical depth of vortices (areas of rotation) are analyzed. These may confirm  the  presence  of  mesocyclones  or  tornadoes and make a strong case for severe weather when linked to  other  products.  VCS  is  an  excellent  tool  for determining  divergence,  convergence,  and  cyclonic and anticyclonic rotation. Figure 2-47 is an example of the  Velocity  Cross-Section  product. The limitations of this product are similar to the Reflectivity Cross-Section product. Keep in mind that the plane along which the cross section is built MUST be either parallel or perpendicular to the radar viewing direction. If the cross section is cut at any other angle, you  are  viewing  the  radial  component  of  radial velocities. This makes the data extremely hard to interpret. RADAR CODED MESSAGES The Radar Coded Message is a high-resolution product that provides summary radar information. It is primarily used in the preparation of the National Radar Summary Chart. The message is composed of three parts. Part A is a reflectivity graphic product that is automatically generated by the system. The local grid at each antenna site is designed to become part of the national radar grid. Part B contains a single profile of the horizontal wind information derived from the output  of  the  Velocity  Azimuth  Display  (VAD) algorithm. It is also produced automatically and is presented to the user as an alphanumeric message. Part C  contains  remarks  in  an  alphanumeric  format. Remarks,   such   as   tornadic   vortex   signatures, 2-51