vi
5.3 Graphical Airman’s Meteorological Advisory (G-AIRMET)5-23
5.3.1 G-AIRMET Issuance5-24
5.3.2 G-AIRMET Content5-24
5.3.3 Use5-30
5.4 Center Weather Advisory (CWA)5-30
5.4.1 CWA Issuance5-30
5.4.2 CWA Criteria5-31
5.4.3 CWA Format and Example5-32
5.5 Meteorological Impact Statement (MIS)5-33
5.5.1 Valid Period5-34
5.5.2 Content5-34
5.5.3 Format5-34
5.6 Additional Products for Convection5-35
5.6.1 Convective Outlooks (AC)5-35
5.6.2 Watch Notification Messages5-38
5.6.3 Traffic Flow Management (TFM) Convective Forecast (TCF)5-46
5.6.4 Extended Convective Forecast Product (ECFP)5-50
5.6.5 National Convective Weather Forecast (NCWF)5-51
5.7 Products for Tropical Cyclones5-56
5.7.1 Tropical Cyclone Advisory (TCA)5-56
5.8 Volcanic Ash Forecasts5-58
5.8.1 Volcanic Ash Advisory Center (VAAC)5-58
5.8.2 Volcanic Ash Advisory (VAA)5-59
5.9 Graphical Forecast for Aviation (GFA)5-61
5.9.1 Time Selection and Slider5-62
5.9.2 GFA Static Images5-64
5.9.3 Strengths and Limitations (GFA)5-66
5.9.4 Recommended Action for Users5-67
5.10 Localized Aviation Model Output Statistics (MOS) Program (LAMP)5-67
5.10.1 Strengths and Limitations (LAMP)5-67
5.10.2 Recommended Action for Users5-67
5.11 Area Forecasts (FA)5-68
5.11.1 FA—Gulf of Mexico, Caribbean, Hawaii, and Alaska5-68
vii
5.12 Alaskan Graphical Area Forecasts (FA)5-78
5.12.1 Issuance5-79
5.12.2 Content5-80
5.12.3 Use5-84
5.13 Terminal Aerodrome Forecast (TAF)5-84
5.13.1 Responsibility5-84
5.13.2 Generic Format of the Forecast Text of an NWS-Prepared TAF5-85
5.13.3 Issuance5-105
5.14 Route Forecasts (ROFOR)5-107
5.14.1 Issuance5-107
5.14.2 ROFOR Amendments5-107
5.14.3 ROFOR Corrections5-107
5.14.4 ROFOR Content5-108
5.14.5 Example5-108
5.15 Wind and Temperature Aloft5-109
5.15.1 Wind and Temperature Aloft Forecast (FB)5-109
5.16 Freezing-Level Graphics5-113
5.16.1 Issuance5-114
5.16.2 Format5-114
5.16.3 Use5-114
5.17 Upper-Air Forecasts5-115
5.17.1 Constant Pressure Levels Forecasts5-116
5.18 Short-Range Surface Prognostic (Prog) Charts5-118
5.18.1 Content5-119
5.18.2 Issuance5-121
5.18.3 Use5-121
5.19 Significant Weather (SIGWX) Forecast5-121
5.19.1 Low-Level Significant Weather (SIGWX) Charts5-121
5.19.2 Mid-Level Significant Weather (SIGWX) Chart5-127
5.19.3 High-Level Significant Weather (SIGWX) Charts5-129
5.19.4 Alaska Significant Weather (SIGWX) Charts5-135
5.20 World Area Forecast System (WAFS)5-137
5.20.1 WAFS Forecasts5-137
viii
5.21 Additional Products for Icing and Turbulence5-146
5.21.1 Current and Forecast Icing Products (CIP/FIP)5-146
5.21.2 Graphical Turbulence Guidance (GTG)5-155
5.22 Additional Products for Clouds, Visibility, Weather, and Surface Wind
Forecasts5-160
5.22.1 NWS Aviation Forecast Discussion5-160
5.22.2 NWS National Digital Forecast Database Graphic Products5-162
5.22.3 Cloud Top Heights Product5-173
5.22.4 Cloud Layer Product5-175
5.23 Airport Weather Warning (AWW)5-175
5.23.1 Issuance5-175
5.23.2 Airport Weather Warning (AWW) Format and Example5-176
5.23.3 Use5-176
5.24 Space Weather5-176
5.24.1 NOAA Space Weather Scales5-176
5.24.2 Space Weather Products5-177
5.24.3 Use5-182
5.25 Soaring Forecast5-183
5.25.1 Issuance5-183
5.25.2 Content and Format5-183
5.25.3 Example5-183
Chapter 6. Aviation Weather Tools6-1
6.1 Helicopter Emergency Medical Services (HEMS) Tool6-1
6.1.1 Availability6-1
6.1.2 Content6-1
6.1.3 Strengths and Limitations6-13
6.1.4 Use6-14
6.2 Flight Path Tool6-14
6.2.1 Description6-14
Appendix A. Definition of Common Terms Used in En Route Forecasts and AdvisoriesA-1
Appendix B. Standard Conversion ChartB-1
Appendix C. Density Altitude CalculationC-1
ix
Appendix D. Internet LinksD-1
Appendix E. WSR-88D Weather Radar NetworkE-1
L ist of Figures
Figure 3-1. METAR/SPECI Coding Format3-4
Figure 3-2. ICAO Continental Codes3-5
Figure 3-3. Obscuration Effects on Slant Range Visibility .................................................................................... 3- 14 Figure 3-4. METAR/SPECI Sky Condition Coding ............................................................................................... 3- 16 Figure 3-5. Pilot Weather Report (PIREP) Coding Format .................................................................................... 3- 27 Figure 3-6. Location of WSR-88D Weather Radar in the CONUS and Their Respective Coverage at 4,000 Feet AGL, 6,000 Feet AGL, and 10,000 Feet AGL ................................................................... 3- 38 Figure 3-7. Location of WSR-88D Weather Radar Outside of the CONUS .......................................................... 3- 39 Figure 3-8. WSR-88D (NEXRAD) Weather Radar Echo Intensity Legend........................................................... 3- 40
Figure 3-9. NWS National Radar Mosaic Example, Which Utilizes NEXRAD Base Reflectivity3-42
Figure 3-10. NWS Regional Radar Mosaic Sector Example, Which Utilizes NEXRAD Base Reflectivity3-43
Figure 3-11. Alaska Radar Mosaic Example .......................................................................................................... 3- 43
Figure 3-12. WSR-88D Weather Radar Composite Reflectivity, Single-Site Product Example3-44
Figure 3-13. Creation of a Composite Reflectivity, Single-Site Product ................................................................ 3- 45
Figure 3-14. Weather Radar 0.5º Base Reflectivity (left) versus Composite Reflectivity (right) Comparison3-45
Figure 3-15. WSR-88D Weather Radar Short-Range (124 NM) Base Reflectivity, Single-Site Product Example ............................................................................................................................................. 3- 46 Figure 3-16. WSR-88D Weather Radar Long-Range (248 NM) Base Reflectivity, Single-Site Product Example ............................................................................................................................................. 3- 47 Figure 3-17. Radar Coded Message (RCM) Display .............................................................................................. 3- 48 Figure 3-18. WSR-88D Weather Radar Convective Precipitation on the 0.5º Base Reflectivity Product Example ............................................................................................................................................. 3- 49 Figure 3-19. WSR-88D Weather Radar Stratiform Precipitation on the 0.5º Base Reflectivity Product Example ............................................................................................................................................. 3- 50 Figure 3-20. Cone of Silence .................................................................................................................................. 3- 51
Figure 3-21. WSR-88D Weather Radar Beam Blockage on Base Reflectivity Product Example3-52
Figure 3-22. WSR-88D Weather Radar Ground Clutter Example .......................................................................... 3- 52 Figure 3-23. WSR-88D Weather Radar Ghost Example ........................................................................................ 3- 53 Figure 3-24. WSR-88D Weather Radar Angel Example ........................................................................................ 3- 54
Figure 3-25. WSR-88D Weather Radar Anomalous Propagation (AP) Example3-55
Figure 3-26. Wind Farms Have Been Known to Make Benign Echoes Appear as Small Storms3-56
Figure 3-27. WSR-88D vs. TDWR ......................................................................................................................... 3- 63 Figure 3-28. TDWR Site Locations ........................................................................................................................ 3- 64 Figure 3-29. Thunderstorm Producing a Microburst .............................................................................................. 3- 64 Figure 3-30. Visible Satellite Image—U.S. Example ............................................................................................. 3- 66 Figure 3-31. Visible Satellite Data Legend ............................................................................................................. 3- 66 Figure 3-32. Infrared (Color) Satellite Image—U.S. Example ............................................................................... 3- 67
Figure 3-33. Unenhanced Infrared (Black and White) Satellite Image—U.S. Example3-68
Figure 3-34. Infrared (Color) Satellite Image Data Legend .................................................................................... 3- 68
Figure 3-35. Unenhanced Infrared (Black and White) Satellite Image Data Legend3-68
Figure 3-36. W ater Vapor Satellite Image—U.S. Example .................................................................................... 3- 69 Figure 3-37. Water Vapor Satellite Image Data Legend ......................................................................................... 3- 70 Figure 3-38. U.S. Radiosonde Network .................................................................................................................. 3- 71 Figure 3-39. AAWU Surface Observations Example ............................................................................................. 3- 72 Figure 3-40. AAWU Surface Observation Plot Legend ......................................................................................... 3- 73
Figure 3-41. Surface Observations—Aviationweather.gov METAR Interactive Display Example3-77
Figure 3-42. Interactive Display Station Plot Example .......................................................................................... 3- 78 Figure 3-43. Station Plot Sky Symbols ................................................................................................................... 3- 80
Figure 3-44. Surface Observations—Aviationweather.gov METAR Static Display Example3-81
Figure 3-45. Static Display Station Plot Example .................................................................................................. 3- 81
x Figure 3-46. Map of FAA’s Aviation Weather Camera Network in Alaska........................................................... 3- 83
Figure 3-47. Sectional Chart Depicting Shungnak (SHG), Alaska Camera Orientations3-83
Figure 3-48. “Clear Day” Image from Aviation Weather Camera Image at Shungnak (SHG), Alaska3-84
Figure 3-49. Aviation Weather Camera Image at Shungnak (SHG), Alaska .......................................................... 3- 84
Figure 4-1. NWS Surface Analysis Chart Example4-1
Figure 4-2. NWS Surface Analysis and Radar Composite Example4-2
Figure 4-3. NWS Surface Analysis Chart Symbols4-3
Figure 4-4. NWS Surface Analysis Chart Station Plot Model4-4
Figure 4-5. NWS Surface Analysis Chart Ship/Buoy Plot Model4-4
Figure 4-6. NWS Surface Analysis Chart for Aviation Interests Station Plot Model4-5
Figure 4-7. NWS Surface Analysis Chart Common Weather Symbols4-6
Figure 4-8. NWS Surface Analysis Chart Wind Plotting Model4-7
Figure 4-9. NWS Surface Analysis Chart Pressure Trends4-8
Figure 4-10. NWS Surface Analysis Chart Sky Cover Symbols4-9
Figure 4-11. Unified Surface Analysis Chart Example .......................................................................................... 4- 11 Figure 4-12. Unified Surface Analysis Chart Example .......................................................................................... 4- 12
Figure 4-13. Unified Surface Analysis Chart Example With Fixed Area Coverage Over Alaska4-13
Figure 4-14. CONUS Display of CVA Ceiling Analysis........................................................................................ 4- 15 Figure 4-15. Regional Display of CVA Ceiling Analysis ....................................................................................... 4- 16 Figure 4-16. Regional Display of CVA Visibility Analysis ................................................................................... 4- 17 Figure 4-17. Regional Display of CVA Flight Category Analysis ......................................................................... 4- 18 Figure 4-18. Weather Depiction Chart—Example.................................................................................................. 4- 20
Figure 4-19. NWS NCEP Central Operations Model Analyses and Guidance Website4-21
Figure 4-20. 500 MB Analysis Chart—Example .................................................................................................... 4- 22 Figure 4-21. 500 MB Height, Temperature, and Wind, 00-hour Forecast (i.e., Model’s Analyses from the NWS’s North American Model (NAM) Example) ............................................................................ 4- 22 Figure 4-22. Skew-T Diagram—Example .............................................................................................................. 4- 24 Figure 4-23. Skew-T Diagram—Multiple Freezing Level Example ...................................................................... 4- 25 Figure 4-24. Skew-T Diagram—Cloud Top Example ............................................................................................ 4- 25
Figure 5-1. AWC SIGMET Areas of Responsibility—Continental U.S5-2
Figure 5-2. AWC SIGMET Areas of Responsibility—Atlantic Basin5-2
Figure 5-3. SIGMET Areas of Responsibility—Pacific Basin5-3
Figure 5-4. SIGMET for the Continental U.S.—Example5-5
Figure 5-5. AWC Convective SIGMET Areas of Responsibility5-8
Figure 5-6. Convective SIGMET Decoding—Example5-9
Figure 5-7. SIGMET Outside the Continental U.S. Decoding Example ................................................................ 5- 13 Figure 5-8. AWC AIRMET Areas of Responsibility—Continental U.S. ............................................................... 5- 17
Figure 5-9. AAWU Flight Advisory and Area Forecast (FA) Zones—Alaska5-17
Figure 5-10. WFO Honolulu AIRMET Areas of Responsibility—Hawaii5-18
Figure 5-11. AIRMET Bulletin Decoding—Example ............................................................................................ 5- 21
Figure 5-12. G- AIRMET—Ceiling and Visibility (IFR) Snapshot Example5-25
Figure 5-13. G- AIRMET—Mountain Obscuration Snapshot Example .................................................................. 5- 25 Figure 5-14. G- AIRMET—Icing Snapshot Example ............................................................................................. 5- 26 Figure 5-15. G- AIRMET—Freezing Level Snapshot Example .............................................................................. 5- 27 Figure 5-16. G- AIRMET—Turbulence-High Snapshot Example .......................................................................... 5- 28 Figure 5-17. G- AIRMET—Turbulence-Low Snapshot Example ........................................................................... 5- 28
Figure 5-18. G- AIRMET—Low-Level Wind Shear (LLWS) Snapshot Example5-29
Figure 5-19. G- AIRMET—Strong Surface Winds Snapshot Example .................................................................. 5- 30
Figure 5-20. Center Weather Service Unit (CWSU) Areas of Responsibility5-31
Figure 5-21. Center Weather Advisory (CWA) Decoding Example ...................................................................... 5- 32 Figure 5-22. Day 1 Categorical Convective Outlook Graphic Example ................................................................. 5- 36
Figure 5-23. Categorical Outlook Legend for Days 1-3 Convective Outlook Graphic Example5-36
Figure 5-24. Aviation Watch (polygon) Compared to Public Watch (shaded) Example5-39
Figure 5-25. TFM Convective Forecast (TCF)—Example ..................................................................................... 5- 47 Figure 5-26. TFM Convective Forecast (TCF)—Example ..................................................................................... 5- 48 Figure 5-27. TCF Product Legend .......................................................................................................................... 5- 48
xi Figure 5-28. ECFP Example ................................................................................................................................... 5- 50 Figure 5-29. NCWF Example ................................................................................................................................. 5- 52 Figure 5-30. NCWF Hazard Scale .......................................................................................................................... 5- 53 Figure 5-31. NCWF One-Hour Extrapolated Forecast Polygon, Forecast Movement Velocity and Echo Tops—Example.................................................................................................................................. 5- 54 Figure 5-32. NCWF Past Performance Polygons—Example ................................................................................. 5- 55 Figure 5-33. Volcanic Ash Advisory Centers (VAACs)......................................................................................... 5- 59 Figure 5-34. Volcanic Ash Advisory in Graphical Format ..................................................................................... 5- 61 Figure 5-35. Aviation Forecast for Clouds—Example ........................................................................................... 5- 62 Figure 5-36. Time Selection and Slider .................................................................................................................. 5- 62 Figure 5-37. Forecast Weather Products Tabs ........................................................................................................ 5- 63 Figure 5-38. Observations/Warnings Tab ............................................................................................................... 5- 64 Figure 5-39. GFA Static Cloud Forecast ................................................................................................................ 5- 65 Figure 5-40. GFA Surface Forecast ....................................................................................................................... 5- 66
Figure 5-41. AWC Area Forecast (FA) Region and WMO Header—Gulf of Mexico5-69
Figure 5-42. AWC Area Forecast (FA) Region and WMO Header—Caribbean5-70
Figure 5-43. WFO Honolulu Area Forecast (FA) Region and WMO Header—Hawaii5-70
Figure 5-44. AAWU Flight Advisory and Area Forecast Zones—Alaska ............................................................. 5- 71
Figure 5-45. Alaskan Graphical Area Forecast (FA)—Flying Weather Example5-80
Figure 5-46. Alaskan Graphical Area Forecast (FA)—Surface Chart Example5-81
Figure 5-47. Alaskan Graphical Area Forecast (FA)—Icing Forecast Example5-82
Figure 5-48. Alaskan Graphical Area Forecast (FA)—Turbulence Forecast Example5-83
Figure 5-49. Alaskan Graphical Area Forecast (FA)—Convective Outlook .......................................................... 5- 84 Figure 5-50. Microburst Effect on Landing Aircraft .............................................................................................. 5- 95 Figure 5-51. FB Wind and Temperature Aloft Interactive Display Example ....................................................... 5- 110 Figure 5-52. Aviationweather.gov Freezing Level Graphic—Example ............................................................... 5- 115
Figure 5-53. NWS NCEP Central Operations Model Analyses and Guidance Website5-116
Figure 5-54. 300 MB Constant Pressure Forecast—Example .............................................................................. 5- 117 Figure 5-55. NDFD Surface Prog Forecast—Example ......................................................................................... 5- 119 Figure 5-56. Surface Prog Forecast Symbols ........................................................................................................ 5- 120 Figure 5-57. 12-Hour Low-Level SIGWX Chart—Example ................................................................................ 5- 122 Figure 5-58. Low-Level SIGWX Chart Symbols ................................................................................................. 5- 123 Figure 5-59. Low-Level SIGWX Chart Flying Categories—Example ................................................................. 5- 123 Figure 5-60. Low-Level SIGWX Chart Turbulence Forecast—Example............................................................. 5- 124 Figure 5-61. Low-Level SIGWX Chart Freezing Level Forecast—Example ....................................................... 5- 125
Figure 5-62. Low-Level SIGWX Chart Multiple Freezing Levels—Example5-126
Figure 5-63. Mid-Level SIGWX Chart—Example ............................................................................................... 5- 127 Figure 5-64. High-Level SIGWX Chart—Example ............................................................................................. 5- 130 Figure 5-65. High-Level SIGWX Chart Turbulence—Examples ......................................................................... 5- 132 Figure 5-66. High-Level SIGWX Chart Jet Stream—Example ............................................................................ 5- 133 Figure 5-67. High-Level SIGWX Chart Tropopause Height—Examples ............................................................ 5- 133 Figure 5-68. High-Level SIGWX Chart Tropical Cyclone—Examples ............................................................... 5- 134 Figure 5-69. High-Level SIGWX Chart Volcanic Eruption Site—Example ........................................................ 5- 134
Figure 5-70. High-Level SIGWX Chart Widespread Sandstorm and Duststorm—Example5-134
Figure 5-71. Alaska Significant Weather Chart—Example .................................................................................. 5- 136
Figure 5-72. WAFS Wind and Temperature 6-Hour Forecast at FL390—Example5-139
Figure 5-73. WAFS CAT Forecast—Example ..................................................................................................... 5- 142 Figure 5-74. WAFS Turbulence Forecast—Example ........................................................................................... 5- 143 Figure 5-75. WAFS Icing Forecast—Example ..................................................................................................... 5- 144 Figure 5-76. WAFS CB Cloud Forecast—Example ............................................................................................. 5- 145 Figure 5-77. C IP/FIP Icing Probability (3,000 Feet MSL)—Example ................................................................. 5- 148 Figure 5-78. CIP/FIP Icing Probability—Max Example ...................................................................................... 5- 149 Figure 5-79. CIP/FIP Icing Severity (3,000 Feet MSL)—Example...................................................................... 5- 150 Figure 5-80. CIP/FIP Icing Severity—Max Example ........................................................................................... 5- 151
Figure 5-81. CIP/FIP Icing Severity Plus Supercooled Large Drops (SLD)—Example5-153
Figure 5-82. CIP/FIP Icing Severity Plus Supercooled Large Droplets (SLD)—Max Example5-154
xii Figure 5-83. GTG—Max Intensity Example CAT+MWT All Levels .................................................................. 5- 157 Figure 5-84. CAT+MWT Low Levels Example (GA Users) ............................................................................... 5- 158 Figure 5-85. Explicit MWT Forecasts Example ................................................................................................... 5- 159
Figure 5-86. Map of NWS Weather Forecast Office’s Area of Responsibility5-161
Figure 5-87. NDFD Sky Cover Graphic Product—Example ................................................................................ 5- 164 Figure 5-88. NDFD Sky Cover Graphic Product—Example ................................................................................ 5- 165 Figure 5-89. NDFD Weather Graphic Product—Example ................................................................................... 5- 166 Figure 5-90. NDFD Weather Graphic Product—Example ................................................................................... 5- 167 Figure 5-91. Legend for NDFD Weather Graphic ................................................................................................ 5- 168 Figure 5-92. NDFD Weather Graphic Product—Example ................................................................................... 5- 169 Figure 5-93. NDFD Weather Graphic Product—Example ................................................................................... 5- 170 Figure 5-94. NDFD Weather Graphic Product—Example ................................................................................... 5- 170 Figure 5-95. NDFD Surface Wind Speed and Direction—Example .................................................................... 5- 171 Figure 5-96. NDFD Wind Speed and Direction Graphic Product Plot Model ...................................................... 5- 172 Figure 5-97. NDFD Surface Wind Gust Graphic—Example ............................................................................... 5- 172 Figure 5-98. Cloud Top Heights Product—Example ............................................................................................ 5- 174
Figure 6-1. HEMS Ceiling with Flight Category Overlay—Example6-3
Figure 6-2. HEMS Visibility with Flight Category Overlay—Example6-3
Figure 6-3. HEMS Flight Category with Flight Category Overlay—Example6-4
Figure 6-4. HEMS Radar Display—Example6-5
Figure 6-5. HEMS Satellite Imagery—Example6-6
Figure 6-6. HEMS Icing Severity—Example6-7
Figure 6-7. HEMS Icing Probability—Example6-7
Figure 6-8. HEMS Temperature—Example6-8
Figure 6-9. HEMS Relative Humidity—Example6-9
Figure 6-10. HEMS Wind Speed with Windbarb—Example6-9
Figure 6-11. HEMS Data Overlays with Text METAR—Example ....................................................................... 6- 12 Figure 6-12. Configure Menu—Example ............................................................................................................... 6- 13
Figure 6-13. Flight Path Tool—Icing Severity Example (Image Credit: AWC)6-15
Figure 6-14. Flight Path Tool—Windbarbs Example (Image Credit: AWC) ......................................................... 6- 16
Figure 6-15. Flight Path Tool—Cross Section Example (Image Credit: AWC)6-17
List of Tables Table 1-1. FIS-B Over UAT Product Update and Transmission Intervals.............................................................. 1- 11 Table 1-2. Product Parameters for Low/Medium/High Altitude Tier Radios ......................................................... 1- 12
Table 3-1. SPECI Criteria3-2
Table 3-2. METAR/SPECI Notations for Reporting Present Weather1 .................................................................. 3- 10 Table 3-3. METAR/SPECI Contractions for Sky Cover ......................................................................................... 3- 15
Table 3-4. METAR/SPECI Increments of Reportable Values of Sky Cover Height3-15
Table 3-5. METAR/SPECI Order of Remarks ........................................................................................................ 3- 18 Table 3-6. METAR/SPECI Type and Frequency of Lightning ............................................................................... 3- 21 Table 3-7. WSR-88D Weather Radar Precipitation Intensity Terminology ............................................................ 3- 41 Table 3-8. Technical Specifications: WSR-88D vs. TDWR ................................................................................... 3- 59 Table 3-9. AAWU Surface Observations Flying Categories and Criteria ............................................................... 3- 73 Table 3-10. AAWU Surface Observation Precipitation Symbols ........................................................................... 3- 75
Table 3-11. AAWU Surface Observation Obstruction to Visibility Symbols3-76
Table 3-12. AAWU Surface Observation Precipitation Intensity Symbols ............................................................ 3- 76 Table 3-13. Rounding of Actual METAR Visibility Values for Depiction on Aviationweather.gov/AWC METAR Display .................................................................................................................................. 3- 79 Table 3-14. Station Plot Weather Categories .......................................................................................................... 3- 80
Table 5-1. Decoding a SIGMET (Non-Convective) for the Continental U.S5-6
Table 5-2. Decoding a Convective SIGMET .......................................................................................................... 5- 10 Table 5-3. Decoding a SIGMET Outside of the Continental U.S. .......................................................................... 5- 13
Table 5-4. AAWU Flight Advisory and Area Forecast (FA) Zones—Alaska5-18
Table 5-5. AIRMET Issuance Schedule .................................................................................................................. 5- 20
xiii Table 5-6. D ecoding an AIRMET Bulletin ............................................................................................................. 5- 22 Table 5-7. G- AIRMET Issuance Schedule.............................................................................................................. 5- 24 Table 5-8. Decoding a Center Weather Advisory (CWA) ...................................................................................... 5- 33 Table 5-9. Convective Outlook Issuance Schedule ................................................................................................. 5- 35 Table 5-10. Decoding an Aviation Weather Watch Notification Message ............................................................. 5- 41 Table 5-11. Weather Elements on Forecast Product Tabs ....................................................................................... 5- 63
Table 5-12. Products Displayed on Observations/Warnings Weather Products Tab5-64
Table 5-13. AAWU Area Forecast (FA) Zones—Alaska ....................................................................................... 5- 71 Table 5-14. Area Forecast (FA) Issuance Schedule ................................................................................................ 5- 72 Table 5-15. Generic Format of NWS TAFs ............................................................................................................ 5- 85 Table 5-16. TAF Fog Terms ................................................................................................................................... 5- 92 Table 5-17. TAF Use of Vicinity (VC) ................................................................................................................... 5- 93 Table 5-18. TAF Sky Cover .................................................................................................................................... 5- 93 Table 5-19. TAF Issuance Schedule ...................................................................................................................... 5- 105 Table 5-20. Wind and Temperature Aloft Forecast Decoding Examples .............................................................. 5- 113 Table 5-21. Wind and Temperature Aloft Forecast (FB) Periods ......................................................................... 5- 113 Table 5-22. Select Constant Pressure Levels From the GFS Model ..................................................................... 5- 118 Table 5-23. Short-Range Surface Prog Forecast Schedule .................................................................................... 5- 121 Table 5-24. Low-Level SIGWX Chart Issuance Schedule .................................................................................... 5- 126 Table 5-25. Icing and Turbulence Intensity Symbols ............................................................................................ 5- 128 Table 5-26. Mid-Level SIGWX Chart Issuance Schedule .................................................................................... 5- 129 Table 5-27. High-Level SIGWX FORECAST Issuance Schedule ....................................................................... 5- 135 Table 5-28. WAFS Clear Air Turbulence Forecasts ............................................................................................. 5- 141 Table 5-29. WAFS In-Cloud Turbulence Forecasts .............................................................................................. 5- 143 Table 5-30. WAFS Global Icing Forecasts ........................................................................................................... 5- 144
Table 6-1. Flight Categories6-2
1-1 CHAPTER 1. AVIATION WEATHER SERVICE PROGRAM The aviation weather service program is a joint effort of the National Weather Service (NWS), the Federal Aviation Administration (FAA), the Department of Defense (DOD), and other aviation-oriented groups and individuals. This chapter discusses the civilian agencies of the U.S. Government and their observation, communication, and forecast services to the aviation community.
1.1 National Oceanic and Atmospheric Administration (NOAA).
NOAA is an agency of the Department of Commerce (DOC). NOAA conducts research and gathers data about the global oceans, atmosphere, space, and sun, and applies this knowledge to science and service, which touches the lives of all Americans. Among its six major divisions are the National Environmental Satellite, Data, and Information Service (NESDIS) and the NWS.
1.1.1 National Environmental Satellite, Data, and Information Service (NESDIS).
The NESDIS manages the U.S. civil operational remote-sensing satellite systems, as well as other global information for meteorology, oceanography, solid-earth geophysics, and solar-terrestrial sciences. NESDIS provides this data to NWS meteorologists and a wide range of other users for operational weather forecasting.
1.1.1.1 Satellite Analysis Branch (SAB).
NESDIS’ SAB serves as the operational focal point for real-time imagery products and multi-disciplinary environmental analyses. The SAB’s primary mission is to support disaster mitigation and warning services for U.S. Federal agencies and the international community. Routine environmental analyses are provided to forecasters and other environmental users, and are used in the numerical models of the NWS. The SAB schedules and distributes real-time satellite imagery products from global geostationary and polar orbiting satellites to environmental users. The SAB coordinates the satellite and other information for the NOAA Volcanic Hazards Alert Program, under an agreement with the FAA, and works with the NWS as part of the Washington, D.C. Volcanic Ash Advisory Center (VAAC). The Washington, D.C. VAAC Area of Responsibility (AOR) includes the continental United States (CONUS), the Gulf of Mexico, the Oakland Flight Information Region (FIR), and the New York FIR.
1.1.2 National Weather Service (NWS).
NWS provides weather data, forecasts, and warnings for the United States, its territories, adjacent waters, and ocean areas for the protection of life and property and the enhancement of the national economy. NWS data and products form a national information database and infrastructure that can be used by other government agencies, the private sector, the public, and the global community. The following is a description of NWS offices associated with aviation weather:
1.1.2.1 National Centers for Environmental Prediction (NCEP).
NCEP is where virtually all global meteorological data is collected and
1-2 analyzed. NCEP then provides a wide variety of national and international weather guidance products to NWS field offices, government agencies, emergency managers, private sector meteorologists, and meteorological organizations and societies throughout the world. NCEP is a critical resource in national and global weather prediction and is the starting point for nearly all weather forecasts in the United States.
NCEP is comprised of nine distinct centers and the Office of the Director.
Each center has its own specific mission. The following NCEP centers provide aviation weather products and services:
1.1.2.1.1 NCEP Central Operations (NCO).
The NCO in College Park, MD, sustains and executes the operational suite of the numerical analysis and forecast models and prepares NCEP products for dissemination. It also links all nine of the national centers together via computer and communications-related services.
1.1.2.1.2 Aviation Weather Center (AWC).
The AWC in Kansas City, MO, issues a suite of aviation weather forecasts in support of the National Airspace System (NAS) including: Airman’s Meteorological Information (AIRMET), significant meteorological information (SIGMET), Convective SIGMETs, Area Forecasts (FA), Significant Weather Prognostic Charts (low, middle, and high), National Convective Weather Forecast (NCWF), Current Icing Product (CIP), Forecast Icing Product (FIP), Graphical Turbulence Guidance (GTG), and Ceiling and Visibility Analysis (CVA) product. The AWC is a Meteorological Watch Office (MWO) for the International Civil Aviation Organization (ICAO).
The website for the AWC is https://www.aviationweather.gov. The AWC’s website provides the aviation community w ith textual, digital, and graphical forecasts, analyses, and observations of aviation-related weather variables.
Additionally, the website provides information for international flights through the World Area Forecast System (WAFS) Internet File Service (WIFS).
The AWC’s website also provides a flight path tool that allows the user to view data along a specific route of flight. Using the flight path tool, a user can view icing, turbulence, temperature, winds, humidity, AIRMETs/SIGMETs, Aviation Routine Weather Report (METAR)/Special Weather Report (SPECI), Terminal Aerodrome Forecast (TAF), etc. both horizontally and vertically. The flight path tool also allows many overlay options, including Air Route Traffic Control Center (ARTCC) boundaries, counties, highways, and rivers. Product animation is also possible on the AWC JavaScript image.
1.1.2.1.3 Weather Prediction Center (WPC).
The WPC in College Park, MD, provides analysis and forecast products specializing in multi-day, quantitative precipitation forecasts and weather
1-3 forecast guidance, weather model diagnostics discussions, and surface pressure and frontal analyses.
1.1.2.1.4 Storm Prediction Center (SPC).
The SPC in Norman, OK, provides tornado and severe weather watches for the CONUS along with a suite of hazardous weather forecasts.
1.1.2.1.5 National Hurricane Center (NHC).
The NHC in Miami, FL, provides official NWS forecasts of the movement and strength of tropical weather systems and issues the appropriate watches and warnings for the CONUS and surrounding areas. It also issues a suite of marine products covering the tropical Atlantic, Caribbean, Gulf of Mexico, and tropical eastern Pacific. In support of ICAO/World Meteorological Organization (WMO), the NHC is also referred to as the Tropical Cyclone Advisory Center (TCAC).
1.1.2.1.6 Space Weather Prediction Center (SWPC).
The SWPC in Boulder, CO, provides space weather information (e.g., current activity and forecasts) to a wide variety of users. SWPC issues alerts, watches, and warnings for space weather events affecting, or expected to affect, Earth’s environment.
1.1.2.2 Alaska Aviation Weather Unit (AAWU).
The AAWU, located in Anchorage, AK, is an MWO for ICAO. The AAWU is responsible for the entire Anchorage FIR. They issue a suite of aviation weather products for the airspace over Alaska and adjacent coastal waters, including: AIRMETs, SIGMETs, FAs, Graphic FAs, and Significant Weather Prognostic Charts.
The AAWU is also designated as the Anchorage VAAC. The VAAC AOR includes the Anchorage FIR and Far Eastern Russia and is responsible for the issuance of Volcanic Ash Advisories (VAA).
1.1.2.3 Center Weather Service Unit (CWSU).
CWSUs are units of NWS meteorologists under contract with the FAA that are stationed at, and support, the FAA’s ARTCC.
CWSUs provide timely weather consultation, forecasts, and advice to managers within ARTCCs and to other supported FAA facilities. This information is based on monitoring, analysis, and interpretation of real-time weather data at the ARTCC through the use of all available data sources including radar, satellite, Pilot Weather Reports (PIREP), and various NWS products, such as TAFs and inflight advisories.
Special emphasis is given to those weather conditions that are hazardous to aviation or which could impede the flow of air traffic within the NAS. CWSU meteorologists issue the following products in support of their respective
1-4 ARTCC: Center Weather Advisories (CWA) and Meteorological Impact Statements (MIS).
1.1.2.4 Weather Forecast Office (WFO).
An NWS WFO is a multi-purpose, local weather forecast center that produces, among its suite of services, aviation-related products. In support of aviation, WFOs issue TAFs, with some offices issuing Airport Weather Warnings and Soaring Forecasts.
The Honolulu WFO is unique among NWS WFOs in that it provides multiple services beyond the typical WFO. WFO Honolulu is also designated as an MWO for ICAO. As a result of this unique designation, WFO Honolulu is the only WFO to issue the following text products: AIRMETs, SIGMETs, and Route Forecasts (ROFOR). WFO Honolulu is co-located with the Central Pacific Hurricane Center (CPHC). CPHC provides official NWS forecast of the movement and strength of tropical weather systems and issues the appropriate watches and warnings for the central Pacific, including the state of Hawaii. WFO Honolulu also issues a suite of marine products covering a large portion of the Pacific Ocean. In support of ICAO/WMO, the NHC is also referred to as the TCAC.
1.2 Federal Aviation Administration (FAA).
The FAA, a part of the Department of Transportation (DOT), provides a safe, secure, and efficient airspace system that contributes to national security and the promotion of U.S. aerospace safety. As the leading authority in the international aerospace community, the FAA is responsive to the dynamic nature of user needs, economic conditions, and environmental concerns.
The FAA provides a wide range of services to the aviation community. The following is a description of those FAA facilities that are involved with aviation weather and pilot services:
1.2.1 Air Traffic Control Systems Command Center (ATCSCC).
The ATCSCC is located in Vint Hill, VA. The ATCSCC has the mission of balancing air traffic demand with system capacity. This ensures maximum safety and efficiency for the NAS, while minimizing delays. The ATCSCC utilizes the Traffic Management System (TMS), aircraft situation display, monitor alert, the follow on functions, and direct contact with ARTCC, and Terminal Radar Approach Control (TRACON) facility Traffic Management Units (TMU) to manage flow on a national level.
Because weather is the most common reason for air traffic delays and re-routings, NWS meteorologists support the ATCSCC. These meteorologists, called National Aviation Meteorologists (NAM), coordinate NWS operations in support of traffic flow management within the NAS.
1.2.2 Air Route Traffic Control Center (ARTCC).
An ARTCC is a facility established to provide air traffic control (ATC) service to aircraft