Effective September 1, 2015, the four-panel Low Level  SFC-240 chart was replaced with a two-panel chart. The new  two-panel chart will be the same as the top two panels in the  former four-panel chart, depicting the freezing level and areas  of IFR, MVFR, and moderate or greater turbulence. The bottom  two panels of the chart have been removed. In lieu of these  bottom two panels, an enhanced surface chart that includes  fronts, pressure, precipitation type, precipitation intensity, and  weather type, is displayed. The green precipitation polygons  will be replaced by shaded precipitation areas using the  National Digital Forecast Database (NDFD) weather grid.  of a precipitation area, but the specific character of that area  (snow, rain, hail, VIRGA, etc.) cannot be determined. For  this reason, ATC refers to all weather areas displayed on ATC  radar scopes as “precipitation.”  ARTCC facilities normally use a Weather and Radar  Processor (WARP) to display a mosaic of data obtained  from multiple NEXRAD sites. There is a time delay between  actual conditions and those displayed to the controller.  The precipitation data on the ARTCC controller’s display  could be up to 6 minutes old. The WARP processor is only  used in ARTCC facilities. All ATC facilities using radar  weather processors with the ability to determine precipitation  intensity, describe the intensity to pilots as:  Figure 13-13  depicts the new two-panel significant weather  prognostic chart, as well as the symbols typically used to  depict precipitation. The two panels depict freezing levels,  turbulence, and low cloud ceilings and/or restrictions to  visibility (shown as contoured areas of MVFR and IFR  conditions). These charts enable the pilot to pictorially  evaluate existing and potential weather hazards they may  encounter. Pilots can balance weather phenomena with  their aircraft capability and skill set resulting in aeronautical  decision-making appropriate to the flight. Prognostic charts  are an excellent source of information for preflight planning;  however, this chart should be viewed in light of current  conditions and specific local area forecasts.  The 36- and 48-hour significant weather prognostic chart is  an extension of the 12- and 24-hour forecast. This chart is  issued twice a day. It typically contains forecast positions and  characteristics of pressure patterns, fronts, and precipitation.  An example of a 36- and 48-hour surface prognostic chart is  shown in  Figure 13-14 .  When the WARP is not available, a second system, the  narrowband Air Route Surveillance Radar (ARSR) can  display two distinct levels of precipitation intensity that  is described to pilots as “MODERATE and “HEAVY TO  EXTREME.”  ATC facilities that cannot display the intensity levels of  precipitation due to equipment limitations describe the  location of the precipitation area by geographic position or  position relative to the aircraft. Since the intensity level is not  available, the controller states “INTENSITY UNKNOWN.”  Although ATC systems cannot always detect the presence  or absence of clouds, they can often determine the intensity  ATC radar is not able to detect turbulence. Generally,  turbulence can be expected to occur as the rate of rainfall or  intensity of precipitation increases. Turbulence associated  with greater rates of precipitation is normally more severe than  13-16  Figure 13-13.  Significant weather prognostic chart.  ATC Radar Weather Displays  •  Light  •  Moderate  •  Heavy  •  Extreme 