CLD TOP AGE: 18min MAP NRST WPT AUX BAKERSFIELD VISALIA FRESNO 30NM 5 338 1 1652 200 46 13.7 2300 23.0 NAV1 116.00 114.80 NAV2  113.90 114.60 123.850 125.100  COM1 118.600 120.600 COM2 GS  123kts  DIS  53.2NM ETE  25:58  ESA  16800 ENGINE ECHO TOP CLD TOP LTNG CELL MOV SIG / AIR METAR NEXRAD LEGEND MORE WX MAP - NAVIGATION MAP NORTH UP LIGHTNING MODE CELL STRIKE RATE 0 H H H H H H H H H H H H H H H H H H 25 n  m 50 n  m Figure 5-16. Lightning strikes shown on an MFD. Figure 5-17. Cloud cover and cloud tops shown on an MFD. Clouds Lightning Other Weather Products Using Advanced Weather Data Systems 5-12 “clear skies.” Skillful users of weather radar are able to  recover clues of other weather phenomena, such as hail and  turbulence, from radar data. electrical discharges provided by an onboard lightning system  are usually quite accurate. Estimates of the range (or distance)  of electrical discharges tend to be less accurate. Broadcast (or data link) weather services are also capable of  transmitting lightning data to the cockpit. The symbology  used to present lightning data derived from these sources is  similar to that used by onboard lightning detection systems.  The lightning data provided by ground weather surveillance  systems is also a delayed weather product. Since the lightning  data provided by a broadcast service is derived from multiple  sensors, estimates of the range of electrical discharges are  more accurate than those provided by onboard systems. A second limitation of weather radar is that the earliest  (cumulus) stage of a thunderstorm is usually free of  precipitation and may not be detected by radar. Convective  wind shear, severe turbulence, and icing are characteristic  of thunderstorms during the cumulus stage. The pilot must beware of areas that offer no radar coverage.  In many cases, these areas appear blank on a weather display.  The absence of weather hazards as shown on a screen does  not imply the actual absence of weather hazards. Most MFDs are also capable of depicting electrical activity  that is indicative of lightning. Like radar data, lightning data  can come from two sources: onboard and broadcast weather  systems. Both systems have strengths and limitations and  work together to present a more complete weather picture.  Lightning data is an excellent complement to radar data for  detecting the presence of thunderstorms. Weather products that describe cloud coverage are generally  available only from broadcast weather services. One popular  broadcast weather service offers graphical displays of visible  cloud cover along with the cloud top altitude as determined  from satellite imagery.  Figure 5-17 shows an MFD that  depicts cloud cover and cloud tops. An onboard lightning detection system consists of a  simple antenna and processing unit that senses electrical  discharges in the atmosphere and attempts to determine  which electromagnetic signals have the “signature” of  lightning strikes. Lightning detectors or spherics receivers,  such as Stormscope$^{®}$ and Strikefinder $^{®}$, have been known  to indicate areas of static consistent with turbulence even  where there was no rain associated with the turbulence. The  MFD in  Figure 5-16  depicts lightning strikes detected by  a lightning detection system. Onboard lightning detection  systems provide real‑time information about electrical  discharges. Estimates of the direction (or azimuth) of  Broadcast weather services offer many of the other weather  products that can be obtained during a pre-flight briefing  on the ground. Broadcast weather services can also provide  graphical wind data, SIGMETs and AIRMETs, freezing  levels, temporary flight restrictions, surface analyses, and  hurricane tracks. The MFD in  Figure 5-18  shows METAR  and TAF data. The increased availability of weather information is changing  the way pilots think about weather briefing and the weather  decision‑making process. You are no longer limited to  obtaining weather forecast products prior to a flight, only  to discover different actual flight conditions in the air. Now 