Lesson 2-4 Weather Forecasting

1. Lesson 2-4Weather Forecasting

2. Lesson Overview • The history of weather forecasting • The types of instruments used in weather forecasting • The various types of communication methods used to provide weather information Chapter 2, Lesson 4

3. The First Aviation Weather Forecast -- 1918 • Weather forecasts done by US Weather Bureau • Now called NOAA’s National Weather Service • Early meteorologists used primitive methods • Attached instruments to kites and tethered balloons • Only data on temperature and wind direction • First reports were used by pilots carrying mail between New York and Chicago • Mostly only provided local conditions -- not forecasts

4. Weather Reports Address Safety Issues • By 1920, half of airmail service pilots died on the job • Congress passed Air Commerce Act on 20 May 1926 • Directed US Weather Bureau to0 make air travel safer • Focus on safety also boosted commercial passenger business • Today U.S. has one of world’s most advanced aviation weather forecasting systems • Produces 4 million aviation weather forecasts each year Courtesy of USAF

5. Air Force Weather Agency • Army set up its first military weather service in 1917 • AFWA partners with NOAA’s National Weather Service to improve weather science • AFWA provides worldwide coverage today • Since WWII, AFWA has provided hurricane reconnaissance

6. The Types of Instruments Used in Weather Forecasting—Surface • 4 types of observations: • Surface • Upper Air • Radar • Satellite • Surface observations are generally in an area within a 5-mile radius from an airport • Data collected on wind, visibility, pressure, temperature, dew point, sky conditions (cloud cover

7. Instruments Used to Study Surface Weather • Thermometers -- Temperature • Barometers -- Pressure • Aneroids -- flexible metal bellows that respond to changes in atmospheric pressure • Psychrometer -- Relative Humidity • Anemometer -- Wind Speed

8. Surface Weather -- ASOS • Automated Surface Observing System • Joint program of NWS, FAA, and DoD • Our main surface weather observing network • Provides surface observations non-stop, every minute, 24 hours a day, 365 days a year • Computer-generated voice broadcasts • Can also provide broadcasts in print and over-the-phone • Limitations – can’t report weather: • Over the horizon • Above 12,000 feet • Tornadoes • Freezing Drizzle • Snow Depth Chapter 2, Lesson 4

9. Upper Air • More challenging than surface observations • Data collected in two ways: • 1. Radiosondes • Small instruments suspended from weather balloons • Collect data such as air temperature, pressure, wind speed, and wind direction • 2. Pilots • Only real-time source of information regarding turbulence, icing, and cloud heights • Some aircraft also equipped with instruments that can report weather data to dispatchers on the ground

10. VIDEOWeather Balloon Radiosonde

11. Radar • An instrument that sends out and receives radio waves (invisible electromagnetic waves) • Reflectivity is the strength of a returned signal—to gauge a storm’s intensity • On moving and fixed objects, radar can identify: • Distance • Strength • Direction • Speed

12. Four Types of Radar • 1. Doppler—common name : WSR-88D NEXRAD • Two modes of operation: Clear Air and Precipitation • More than 160 Doppler radars are scattered throughout the United States and overseas • Max Range of each radar is 250 miles • Data is converted into brightly colored maps giving info on distance, strength and velocity of weather fronts • Can provide info on tornados to 13 minutes in advance • Run by the US Department of Commerce, DoD, and DOT • The heart of the Doppler operation is the Radar Operations Center in Norman, Oklahoma

13. Doppler Radar

14. Four Types of Radar • 2. FAA terminal Doppler -- found at major airports • Provides severe weather alerts and warnings to air traffic controllers • Warns pilots of wind shear, gust fronts. Amd heavy precipitation near airports (for takeoff and landing) • 3. FAA airport surveillance • Main purpose is to detect aircraft • Air Traffic Controllers also use it to know location and strength of precipitation so they can divert aircraft around severe weather

15. Four Types of Radar • 4. Aircraft airborne radar -- flown on aircraft • Radar can spot a big thunderstorm as well as detect light rainfall • Can also tell how big a storm is

16. VIDEOUsing Airborne Radar

17. Satellites • The Geostationary Operational Environmental Satellite (GOES) • Launched in 1975 by NASA for NOAA • Currently 4 satellites operate in geostationary orbits • Satellites remain over the same part of the earth all the time • Used to track: • Thunderstorms • Tornados • Fog • Mud Slides • Dust Storms, volcanoes, wild fires

18. GOESSatellites

19. VIDEOGOES-R Satellite

20. Satellite Weather Products • SIGMETs (Significant Meteorological Information • Can cover areas of at least 3000 square miles • Provides data on weather that reduces visibility to less than 3 miles • Severe and extreme turbulence • Severe icing • Widespread dust or sandstorms Chapter 2, Lesson 4

21. Satellite Weather Products • AIRMETs (Airman’s Meterological Information) • Weather advisories issued to modify earlier forecasts and reports • Especially vital to pilots of smaller aircraft or pilots with limited experience • Does not cover severe weather events like SIGMETS • Reports include: • Moderate icing and turbulence • Winds of 30 knots or more • Ceilings of less than 1,000 feet • Visibility less than 3 miles

22. VIDEONASA’s A-TRAIN

23. Weather Outlets • Purpose: Get the latest weather data to pilots • Who: FAA, NOAA, NWS, Private Groups • Outlets: • AFSS: Automated Flight Service Station • Main source for preflight weather reports • Briefing available 24 hours by phone • Tailors info for pilot’s route, type of aircraft, type of flight (VFR or IFR), altitude, etc • Can also provide in-flight weather data

24. Weather Outlets • Outlets (continued): • TIBS: Transcribed Information Briefing Service • Briefings are prerecorded, quick rundown of weather • Includes special announcement • Does not replace fuller pre-flight briefings • EFAS: En Route Flight Advisory Service • Also called “Flight Watch” • Used once the pilot is airborne • One of best sources for current weather along a route • Limitation: Not available 24 hours a day

25. Weather Outlets • Outlets (continued): • HIWAS: Hazardous Inflight Weather Advisory Service • Broadcasts bad weather alerts 24 hours a day • Broadcasts are just summaries • Pilots would use other services if they want more detailed info

26. Types of Briefings • Standard • Most complete report used before departure • Provides an overall weather picture • Adverse conditions; airport closings • Recommendation regarding VFR or IFR • Fronts and other major weather systems in area • Ceilings, winds, temperatures • Enroute weather forecasts • Destination weather at time of landing • NOTAMS: Notices to Airmen => airport closings and restricted flight space (e.g., around DC area)

27. VIDEOStandard Pilot Weather Brief

28. Types of Briefings • Abbreviated • Shortened version of the standard • Used to update a standard brief you already have • Add one or two weather items you don’t yet have • Outlook • At least 6 hours in advance of your planned departure time • Can influence route, altitude, departure time, etc

29. Current Weather Reports • METARs: Aviation Routine Weather Reports • Hourly reports of current surface weather • Wind direction and speed, visibility, strength and location of precipitation and funnel clouds • PIREPs: Pilot Weather Reports • Current upper air conditions such as icing • RAREPs: Radar Weather Reports • Also known as SDs (Storm Detections) • Current readings of precip and thunderstorms

30. Forecast Weather Reports • TAFs: Terminal Aerodrome Forecasts • —cover a five-mile radius around airports • FAS: Area Forecasts • Give picture of clouds, general weather, and visual conditions over large area (several states) • SIGMETs and AIRMETs • See earlier slides • FDs: Winds and Temperature Aloft Forecasts • Predict winds and temperatures for specific spots based on upper air readings from radiosondes

31. WeatherCharts • Surface analysis chart: • Assesses current surface weather • Shows areas of high and low pressure, fronts, temps, dew points, wind directions/speed, visual obstructions

32. WeatherCharts • Radar summary chart: • Marks precipitation cells only; published every hour • Marks areas of severe weather (tornadoes, thunderstorms) with heavy dashed lines

33. WeatherCharts • Significant weather prognostic charts: • Forecast weather—does not provide current weather • Predicts turbulence, freezing levels, and IFR weather

34. Standard UniformAltimeterSetting • How does an altimeter work? • It’s a simple barometer set to convert to pressure reading to the atmospheric altitude • Average sea-level pressure is 29.92 • Above 18,000 feet, all planes set altimeter to have sea-level pressure at 29.92 • This ensures aircraft will know what altitude they are in relation to other aircraft • What would happen if an aircraft used something different than 29.92, say 28.86 when they took off?

35. AtmosphericPressure and TemperatureTable • Atmospheric Pressure Table

36. Next…. • Done – weather forecasting • Next – the effects of weather on aircraft Chapter 2, Lesson 4 Courtesy of AP Photo.