Aviation Weather HandbookFAA-H-8083-28B
Front Matter
14 pagesPages iii–xv
- Aviation Weather Handbook
- 2026
- United States Department of Transportation
- FEDERAL AVIATION ADMINISTRATION
- Flight Standards Service
Preface
This handbook is designed as a technical reference for all who operate in the National Airspace System (NAS). Pilots, dispatchers, and operators will find this handbook a valuable resource for flight planning and decision making.
This handbook conforms to pilot weather training and certification concepts established by the Federal Aviation Administration (FAA). The discussion and explanations reflect the most commonly used weather products and information.
It is essential for persons using this handbook to also become familiar with and apply the pertinent parts of Title 14 of the Code of Federal Regulations (14 CFR) and the Aeronautical Information Manual (AIM). Title 14 CFR, the AIM, this handbook, current advisory circulars (AC), and other FAA technical references are available via the internet at the FAA home page at https://www.faa.gov.
This handbook is available for download in Portable Document Format (PDF) from the FAA’s Regulations and Policies web page at https://www.faa.gov/regulations_policies/handbooks_manuals/aviation.
This handbook was signed and published by the U.S. Department of Transportation (DOT), FAA Aviation Safety, Flight Standards Service (FS) on April 2, 2026.
The guidance and recommendations in this handbook are not legally binding in their own right and will not be relied upon by the FAA as a separate basis for affirmative enforcement action or other administrative penalty. Conformity with the guidance and recommendations is voluntary only and nonconformity will not affect rights and obligations under existing statutes and regulations.
NOTE: Recently the National Weather Service’s (NWS) Aviation Weather Center’s (AWC) updated their website (https://aviationweather.gov). There have been numerous and significant changes to that website. This revision of the Aviation Weather Handbook includes references to that website. To prevent the need for many updates to this Handbook there are fewer AWC Website images copied from there.
Comments regarding this publication should be sent, in email form, to the following address: 9-AWA-AFS400-Coord@faa.gov.
Acknowledgements
This document was prepared under FAA Contract DTFAWA-15-D-00031 with support from AvMet Applications, Inc.
Individual photographic contributions were made by Blake Spry (front cover), Luke Culver (front cover and cover of Chapter 15), and Larry Burch (covers of Chapters 1, 2, 3, 4, 5, 7, 8, 9, 10, 11, 13, 14, 16, 18, 23, 24, 25, 26, 27, 28, Part 1, Part 2, and Part 3). Cover of Chapter 20 courtesy of the National Research Council of Canada.
Notice
The U.S. Government does not endorse products or manufacturers. Trade or manufacturers’ names appear herein solely because they are considered essential to the objective of this handbook.
Major Revisions
Updated the Preface.
Updated references throughout the handbook changing Notices to Air Mission (NOTAM) to Notice to Airmen (NOTAM).
In Section 2,
Added NASA to the Aviation Weather Service Program description
Added wording on WAFS grids
Added CERAP to the Section 2.3.3 title
Added Alaska’s new dedicated phone number information
In Section 3,
Added new Section 3.3.3.4
Changed “GTG” to “GTGN”, Added “GTG” to the Forecast section on Table 3-1
Added “NDFD” to Table 3-1 and Table 3-2
In Section 4, added a note on Figure 4-1.
In Section 5,
Added “For additional information on how temperature may affect flight performance, please see Chapter 8” to Section 5.1
Removed reference to specific heat capacity to Section 5.7
Removed “capacity” from the name and column heading on Table 5-4
Removed “capacity” from the two paragraphs at the bottom of page 5-9
Adjusted wording in Section 5.7 (first paragraph) to improve accuracy
In Section 15, added a new section on chaff and figure showing radar image of chaff.
In Section 16, added an enhancement to Figure 16-6 for clarity.
In Section 19, added wording for clarity in Section 19.2.2.
In Section 20,
Changed SLD minimum size to 50 microns
Deleted a reference to altitude in Section 20.4.1
Replaced wording in Section 20.4.1 for clarity
In Section 22, added “Do not” to the front of #7.
In Section 23,
Reworded Section 23.1’s introduction for clarity
Updated language on our understanding of the physics of sunspots
Updated language around magnetic fields
Updated the range of frequencies of solar electromagnetic emissions
Added a definition of corona
Refined the description of the cause of an aurora
Changes percentage of GCR flux for consistency with recent publications
In Section 24,
Due to changes on the AWC website, language was updated and multiple figures were deleted
Changed “sm” to “SM” in several locations.
Deleted “, or Dust/Sand Whirl (Dust Devil)” from the first column in Table 24-2
Added a note in Section 24.4.3.7 saying “Note: The link to the RVR website is located in Appendix G.”
Deleted Section 24.6.1.5 and Figure 24-18, both are no longer used
Updated Section 24.9.1 provided the new Weather Camera Program information
In Section 25,
Added Analyzed Weather to the Introduction
Removed reference to the AWC website
Changed Figure 25-3 and 25-16
Deleted graphic references no longer available
Deleted Figures 25-25, 25-26, and 25-27
Enhanced the description of the weather products that are used to generate CIP 2 changes
Deleted “icing” from “AWC’s icing website”
Changed Section 25.6’s title for clarity
Corrected Section references in Section 25.5
In Section 26, deleted Figure 26-8 and all references to the figure.
In Section 27,
Deleted references to the AWC GFA Tool
Deleted Figures 27-1, 27-2, 27-33, 27-34, 27-35
Deleted Section 27.12.3 and 27.12.4, sections renumbered
Removed missing reference information from end of Section 27.12.3 sentence
Deleted sentence referencing the AWC website
Changed the typo at the end of Section 27.2.1.1.2 (4th line) under “Sample winds aloft text message” and top of next page from 550252 to 750252
Updated PROB 30 wording to reflect NWS changes
Added language around the use of temperature information from the LAMP/MOS product
Added text “The NWS will continue producing text FAs for Alaska for the foreseeable future”
Added language for clarity, deleted PIREPs from FIP sourcing, and removed bullets referencing CIP and FIP
Added language around use of the LAMP product for destination forecast planning
Removed “Implementation of additional levels are planned in 2024” and specific location in AWC website
Removed references to FAs for Hawaii, Gulf of America, and the Caribbean
Deleted Sections 27.6.4.2, 27.6.4.3, and 27.6.4.3
Changed definition of heavy ice to Section 27.12
Removed reference to CIP from Section 27.12
In Section 28,
Deleted Figure 28-1 (and references to the figure), Figure 28-2, and Section 28.4
Changed the HEMS Tool to Graphical Forecast for Aviation (Low Altitude, GFA-LA)
Added language in Section 28.2 regarding the change from HEMS to GFA-LA
In Appendices,
Appendix D: Added a reference to RVR in Table D-1
Appendix E Added CERAP and GTG-N
Appendix G: Added FAA Runway Visual Range (RVR) and multiple NWS Website URLs
Table of Contents
Chapter 1. Introduction ........................................................................................................... 1-1
Part 1: Overview of the United States Aviation Weather Service Program and Information
Chapter 2. Aviation Weather Service Program ..................................................................... 2-1
2.1 Introduction ............................................................................................................................... 2-1
2.2 National Oceanic and Atmospheric Administration (NOAA) ................................................... 2-2
2.3 Federal Aviation Administration (FAA) ................................................................................... 2-4
2.4 Department of Defense (DOD) .................................................................................................. 2-5
2.5 Commercial Weather Information Providers ............................................................................. 2-5
Chapter 3. Overview of Aviation Weather Information ......................................................... 3-1
3.1 Introduction ............................................................................................................................... 3-1
3.2 Use of Aviation Weather Information ....................................................................................... 3-2
3.3 Obtaining Weather Information ................................................................................................. 3-3
3.4 Overview of Aviation Weather Products ................................................................................... 3-7
Part 2: Weather Theory and Aviation Hazards
Chapter 4. The Earth’s Atmosphere ....................................................................................... 4-1
4.1 Introduction ............................................................................................................................... 4-1
4.2 Composition............................................................................................................................... 4-2
4.3 Vertical Structure ....................................................................................................................... 4-3
4.4 The Standard Atmosphere ......................................................................................................... 4-5
Chapter 5. Heat and Temperature .......................................................................................... 5-1
5.1 Introduction ............................................................................................................................... 5-1
5.2 Matter ........................................................................................................................................ 5-2
5.3 Energy........................................................................................................................................ 5-2
5.4 Heat............................................................................................................................................ 5-2
5.5 Temperature ............................................................................................................................... 5-2
5.6 Heat Transfer ............................................................................................................................. 5-4
5.7 Thermal Response ..................................................................................................................... 5-8
5.8 Temperature Variations with Altitude ..................................................................................... 5-11
Chapter 6. Water Vapor ........................................................................................................... 6-1
6.1 Introduction ............................................................................................................................... 6-1
6.2 The Hydrologic Cycle ............................................................................................................... 6-2
6.3 Saturation ................................................................................................................................... 6-3
6.4 Relative Humidity...................................................................................................................... 6-4
6.5 Dewpoint ................................................................................................................................... 6-4
6.6 Temperature-Dewpoint Spread (Dewpoint Depression) ........................................................... 6-4
6.7 Change of Phase ........................................................................................................................ 6-5
Chapter 7. Earth-Atmosphere Heat Imbalances .................................................................... 7-1
7.1 Introduction ............................................................................................................................... 7-1
7.2 The Earth-Atmosphere Energy Balance .................................................................................... 7-2
7.3 Heat Imbalances Between Earth’s Surface and the Atmosphere ............................................... 7-3
7.4 Heat Imbalance Variations with Latitude .................................................................................. 7-5
7.5 Seasons ...................................................................................................................................... 7-6
7.6 Diurnal Temperature Variation.................................................................................................. 7-7
Chapter 8. Atmospheric Pressure and Altimetry .................................................................. 8-1
8.1 Introduction ............................................................................................................................... 8-1
8.2 Atmospheric Pressure ................................................................................................................ 8-2
8.3 Density ....................................................................................................................................... 8-7
8.4 Altimetry .................................................................................................................................. 8-10
Chapter 9. Global Circulations and Jet Streams ................................................................... 9-1
9.1 Introduction ............................................................................................................................... 9-1
9.2 Non-Rotating Earth Circulation System .................................................................................... 9-2
9.3 Rotating Earth Circulation System ............................................................................................ 9-2
9.4 Jet Streams ................................................................................................................................. 9-3
Chapter 10. Wind .................................................................................................................... 10-1
10.1 Introduction ............................................................................................................................. 10-1
10.2 Naming of the Wind ................................................................................................................ 10-2
10.3 Forces That Affect the Wind ................................................................................................... 10-2
10.4 Upper Air Wind ....................................................................................................................... 10-6
10.5 Surface Wind ........................................................................................................................... 10-7
10.6 Local Winds ............................................................................................................................. 10-8
10.7 Adverse Winds ...................................................................................................................... 10-16
Chapter 11. Air Masses, Fronts, and the Wave Cyclone Model ......................................... 11-1
11.1 Introduction ............................................................................................................................. 11-1
11.2 Air Masses ............................................................................................................................... 11-2
11.3 Fronts ....................................................................................................................................... 11-4
11.4 The Wave Cyclone Model ....................................................................................................... 11-9
11.5 Dryline ................................................................................................................................... 11-11
Chapter 12. Vertical Motion and Clouds .............................................................................. 12-1
12.1 Introduction ............................................................................................................................. 12-1
12.2 Vertical Motion Effects on an Unsaturated Air Parcel ............................................................ 12-2
12.3 Vertical Motion Effects on a Saturated Air Parcel .................................................................. 12-3
12.4 Common Sources of Vertical Motion ...................................................................................... 12-5
12.5 Cloud Forms ............................................................................................................................ 12-8
12.6 Cloud Levels ............................................................................................................................ 12-8
Chapter 13. Atmospheric Stability ....................................................................................... 13-1
13.1 Introduction ............................................................................................................................. 13-1
13.2 Using a Parcel as a Tool to Evaluate Stability ......................................................................... 13-2
13.3 Stability Types ......................................................................................................................... 13-2
13.4 Processes That Change Atmospheric Stability ........................................................................ 13-7
13.5 Measurements of Stability ....................................................................................................... 13-9
13.6 Convection ............................................................................................................................. 13-11
13.7 Summary ................................................................................................................................ 13-11
Chapter 14. Precipitation ....................................................................................................... 14-1
14.1 Introduction ............................................................................................................................. 14-1
14.2 Necessary Ingredients for Formation....................................................................................... 14-2
14.3 Growth Process ........................................................................................................................ 14-2
14.4 Precipitation Types .................................................................................................................. 14-3
Chapter 15. Weather Radar ................................................................................................... 15-1
15.1 Introduction ............................................................................................................................. 15-1
15.2 Principles of Weather Radar .................................................................................................... 15-2
Chapter 16. Mountain Weather ............................................................................................. 16-1
16.1 Introduction ............................................................................................................................. 16-1
16.2 Mountain Waves and Adverse Winds ..................................................................................... 16-2
16.3 Mountain/Valley Breezes and Circulation ............................................................................. 16-17
16.4 Mountain/Valley Fog ............................................................................................................. 16-17
16.5 Upslope Fog ........................................................................................................................... 16-17
16.6 Mountain Obscuration ........................................................................................................... 16-17
16.7 Mountain Turbulence ............................................................................................................ 16-17
16.8 Mountain Icing ...................................................................................................................... 16-17
16.9 Density Altitude ..................................................................................................................... 16-17
Chapter 17. Tropical Weather ............................................................................................... 17-1
17.1 Introduction ............................................................................................................................. 17-1
17.2 Circulation ............................................................................................................................... 17-2
17.3 Transitory Systems .................................................................................................................. 17-7
Chapter 18. Weather and Obstructions to Visibility ........................................................... 18-1
18.1 Introduction ............................................................................................................................. 18-1
18.2 Low Ceiling and Mountain Obscuration ............................................................................... 18-12
Chapter 19. Turbulence ......................................................................................................... 19-1
19.1 Introduction ............................................................................................................................. 19-1
19.2 Causes of Turbulence .............................................................................................................. 19-2
Chapter 20. Icing .................................................................................................................... 20-1
20.1 Introduction ............................................................................................................................. 20-1
20.2 Supercooled Water .................................................................................................................. 20-2
20.3 Structural Icing ........................................................................................................................ 20-2
20.4 Engine Icing ............................................................................................................................. 20-7
20.5 Additional Information ............................................................................................................ 20-8
Chapter 21. Arctic Weather ................................................................................................... 21-1
21.1 Introduction ............................................................................................................................. 21-1
21.2 Climate, Air Masses, and Fronts.............................................................................................. 21-2
21.3 Arctic Peculiarities .................................................................................................................. 21-4
21.4 Arctic Weather Hazards ........................................................................................................... 21-4
Chapter 22. Thunderstorms .................................................................................................. 22-1
22.1 Introduction ............................................................................................................................. 22-1
22.2 Necessary Ingredients for Thunderstorm Cell Formation ....................................................... 22-2
22.3 Thunderstorm Cell Life Cycle ................................................................................................. 22-2
22.4 Thunderstorm Types ................................................................................................................ 22-3
22.5 Factors that Influence Thunderstorm Motion .......................................................................... 22-5
22.6 Thunderstorm Terminology ..................................................................................................... 22-6
22.7 Hazards .................................................................................................................................... 22-7
22.8 Thunderstorm Avoidance ...................................................................................................... 22-20
Chapter 23. Space Weather ................................................................................................... 23-1
23.1 Introduction ............................................................................................................................. 23-1
23.2 The Sun—Prime Source of Space Weather ............................................................................. 23-2
23.3 The Sun’s Energy Output and Variability ............................................................................... 23-2
23.4 Sunspots and the Solar Cycle .................................................................................................. 23-2
23.5 Solar Wind ............................................................................................................................... 23-2
23.6 Solar Eruptive Activity ............................................................................................................ 23-3
23.7 Geospace .................................................................................................................................. 23-3
23.8 Galactic Cosmic Rays (GCR) .................................................................................................. 23-4
23.9 Geomagnetic Storms................................................................................................................ 23-4
23.10 Solar Radiation Storms ............................................................................................................ 23-4
23.11 Ionospheric Storms .................................................................................................................. 23-5
23.12 Solar Flare Radio Blackouts .................................................................................................... 23-5
23.13 Effects of Space Weather on Aircraft Operations ................................................................... 23-6
Part 3: Technical Details Relating to Weather Products and Aviation Weather Tools
Chapter 24. Observations ..................................................................................................... 24-1
24.1 Introduction ............................................................................................................................. 24-1
24.2 Surface Observations ............................................................................................................... 24-2
24.3 Automated Surface Observing System (ASOS) and Automated Weather Observing System (AWOS) ...................................................................................................................... 24-2
24.4 Aviation Routine Weather Report and Aviation Selected Special Weather Report ................ 24-5
24.5 Aircraft Observations and Reports ........................................................................................ 24-26
24.6 Radar Observations................................................................................................................ 24-36
24.7 Satellite Observations ............................................................................................................ 24-45
24.8 Upper Air Observations ......................................................................................................... 24-51
24.9 Aviation Weather Cameras .................................................................................................... 24-53
Chapter 25. Analysis .............................................................................................................. 25-1
25.1 Introduction ............................................................................................................................. 25-1
25.2 Weather Charts ........................................................................................................................ 25-2
25.3 Upper Air Analysis ................................................................................................................ 25-18
25.4 Freezing Level Analysis ........................................................................................................ 25-23
25.5 Icing Analysis (Current Icing Product (CIP)) ........................................................................ 25-23
25.6 Turbulence [Graphical Turbulence Guidance (GTG)] Analysis ........................................... 25-24
25.7 Real-Time Mesoscale Analysis (RTMA) .............................................................................. 25-24
Chapter 26. Advisories .......................................................................................................... 26-1
26.1 Introduction ............................................................................................................................. 26-1
26.2 Significant Meteorological Information (SIGMET) ................................................................ 26-2
26.3 Airmen’s Meteorological Information (AIRMET) ................................................................ 26-15
26.4 Center Weather Advisory (CWA) ......................................................................................... 26-20
26.5 Volcanic Ash Advisory (VAA) ............................................................................................. 26-23
26.6 Aviation Tropical Cyclone Advisory (TCA) ......................................................................... 26-26
26.7 Space Weather Advisory ....................................................................................................... 26-28
26.8 Low-Level Wind Shear (LLWS)/Microburst Advisories ...................................................... 26-33
26.9 Airport Weather Warning (AWW) ........................................................................................ 26-33
Chapter 27. Forecasts ........................................................................................................... 27-1
27.1 Introduction ............................................................................................................................. 27-1
27.2 Winds and Temperatures Aloft ................................................................................................ 27-3
27.3 Terminal Aerodrome Forecast (TAF) ...................................................................................... 27-6
27.4 Aviation Surface Forecast and Aviation Clouds Forecast ..................................................... 27-22
27.5 Area Forecasts (FA)............................................................................................................... 27-24
27.6 Alaska Graphical Forecasts ................................................................................................... 27-27
27.7 World Area Forecast System (WAFS) .................................................................................. 27-32
27.8 Significant Weather (SIGWX) .............................................................................................. 27-35
27.9 Short-Range Surface Prognostic (Prog) Charts ..................................................................... 27-48
27.10 Upper Air Forecasts ............................................................................................................... 27-50
27.11 Freezing Level Forecast Graphics ......................................................................................... 27-53
27.12 Forecast Icing Product (FIP) .................................................................................................. 27-53
27.13 Graphical Turbulence Guidance (GTG) ................................................................................ 27-54
27.14 Cloud Tops ............................................................................................................................ 27-55
27.15 Localized Aviation Model Output Statistics (MOS) Program (LAMP) ................................ 27-55
27.16 Additional Products for Convection ...................................................................................... 27-56
27.17 Route Forecast (ROFOR) ...................................................................................................... 27-64
27.18 Aviation Forecast Discussion (AFD)..................................................................................... 27-65
27.19 Meteorological Impact Statement (MIS) ............................................................................... 27-66
27.20 Soaring Forecast .................................................................................................................... 27-66
27.21 Balloon Forecast .................................................................................................................... 27-67
Chapter 28. Aviation Weather Tools .................................................................................... 28-1
28.1 Introduction ............................................................................................................................. 28-1
28.2 Graphical Forecasts for Aviation (GFA) Tool ......................................................................... 28-2
28.3 FAA Flight Service’s Interactive Map .................................................................................... 28-2
Appendices
Appendix A. Cloud Types ...................................................................................................... A-1
A.1 High Clouds .............................................................................................................................. A-1
A.2 Middle Clouds .......................................................................................................................... A-3
A.3 Low Clouds............................................................................................................................... A-7
Appendix B. Standard Conversion Chart ............................................................................. B-1
Appendix C. Density Altitude Calculation ............................................................................ C-1
Appendix D. Special Terminal Operation Procedures (STOP) for Operations in a Noncontiguous State .............................................................................................................. D-1
D.1 Introduction .............................................................................................................................. D-1
D.2 Weather Information................................................................................................................. D-1
D.3 Airport Data .............................................................................................................................. D-5
D.4 Flight Planning ......................................................................................................................... D-6
D.5 Preflight Planning and Briefing to STOP Airport .................................................................... D-8
D.6 En Route, Flight Monitoring, and Communications................................................................. D-8
D.7 Destination Approach and Arrival .......................................................................................... D-10
D.8 Departure Procedures From a STOP Airport .......................................................................... D-10
D.9 Training for Dispatchers, Flight Followers, and Flightcrew .................................................. D-11
D.10 Approval ................................................................................................................................. D-12
D.11 Compliance Monitoring, Quality Assurance (QA), and Auditing .......................................... D-13
Appendix E. Abbreviations, Acronyms, and Initialisms ...................................................... E-1
Appendix F. Units of Measurement ....................................................................................... F-1
Appendix G. Websites ............................................................................................................ G-1