AVIATION
WEATHER
SERVICES Advisory Circular, AC 00-45G, Change 1
U.S. DEPARTMENT OF COMMERCE
NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION
NATIONAL WEATHER SERVICE
U.S. DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION
Photo courtesy of Aaron A. Gilstad Published July 29, 2010
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) Summary of Changes
SUMMARY OF CHANGES
SECTION CHANGES
1.1.2.5 Changed wording to say “…and certify non-military pilot weather briefers and tower visibility observers.”
1.3.1 Changed wording from “specialist” to “NWS certified pilot weather briefer”
2.1.1 Changed wording from “are considered” to “pertain to”
2.3 Changed wording from ”defined in paragraph 2.3” to “defined in paragraph 2.2”
2.3.2 Changed wording from “defined in paragraph 2.2.1” to “defined in paragraph
2.1.1”
2.3.3 Change wording from…”(see paragraph 2.4.2, above)” to “(see previous section)”
3.1.3.9 Changed example wording from “cumulonimbus at 7,500” to “…cumulonimbus at 3,200”
3.1.3.13.19.4 Changed order of clouds to list by height (i.e., CCSL, ACSL, SCSL, rotor)
3.2.1 Change wording from “(Figure 3-7)” to “(Figure 3-10)”
3.2.2.1.1 Corrected section numbering typo
3.2.1.7 Changed coding from “/WV” to “/WX”
3.2.1.10 Changed wording to prevent confusion
3.2.1.12.8 Changed wording from “flight level 310” to “flight level 370”
3.3.1 Changed wording from ”(see figure 3-12)” to (see Figure 3-15). Also, changed wording from “Figure 3-8” to “Figure 3-11”
3.3.1.3 Changed wording from ”Figure 3-9” to “Figure 3-12”
3.3.1.11 Changed wording from “Figure 3-11” to Figure 3-14”
4.1.4.1.3.6 Corrected spelling error in Figure 4-11; from “propogation” to “propagation”
4.1.4.2 Deleted long-range Composite Reflectivity since the NWS no longer provides it through ADDS or the (NWS Ridge Radar site).
5.4 Removed this section since the Lifted Index (LI) Analysis DIFAX Chart is no longer produced.
6.2.5 Corrected numbering error on Figure 6-11.
6.3 Inserted G-AIRMET as new primary product. This changed the numbering in the remainder of section 6.
7.1.10 Removed mention of Alaska SIGMETs since they are no longer embedded in the Alaska Area Forecasts (FAs)
9.5 Updated from GTG to the new GTG-2.
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) Foreword
FOREWORD
Aviation Weather Services, Advisory Circular 00-45G, Change 1, is published jointly by the National Weather Service (NWS) and the Federal Aviation Administration (FAA). This publication supplements its companion manual Aviation Weather, Advisory Circular 00-6A, which documents weather theory and its application to the aviation community.
This advisory circular, AC 00-45G, Change 1, explains U.S. aviation weather products and services. It details the interpretation and application of advisories, coded weather reports, forecasts, observed and prognostic weather charts, and radar and satellite imagery. Product examples and explanations are taken primarily from the Aviation Weather Center’s Aviation Digital Data Service website (http://adds.aviationweather.noaa.gov/).
The AC 00-45G, Change 1, was written by Robert A. Prentice with assistance from Douglas D.
Streu. FAA review was provided by Mike Lenz (AFS-810).
An online version of this document (including digital images) can be found at:
http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/MainFram e?OpenFrameSet
Comments and suggestions for improving this publication are encouraged and should be directed to:
NATIONAL WEATHER SERVICE, W/SR64 BLDG 30, RM 107 6500 S MACARTHUR BLVD OKLAHOMA CITY OK 73169-6901 nws-faa.academy@noaa.gov
Aviation Weather Services, Advisory Circular, AC 00-45G, Change 1, supersedes AC 00-45G, published February 11, 2010.
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) Table of Contents Page i
1 AVIATION WEATHER SERVICE PROGRAM1-1
1.1 NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION (NOAA)1-1
1.1.1 National Environmental Satellite Data and Information Service (NESDIS)1-1
1.1.1.1 Satellite Analysis Branch (SAB)1-1
1.1.2 National Weather Service (NWS)1-1
1.1.2.1 National Centers for Environmental Prediction (NCEP)1-1
1.1.2.1.1 NCEP Central Operations (NCO)1-2
1.1.2.1.2 Aviation Weather Center (AWC)1-2
1.1.2.1.3 Hydrometeorological Prediction Center (HPC)1-2
1.1.2.1.4 Storm Prediction Center (SPC)1-2
1.1.2.1.5 Tropical Prediction Center (TPC)1-2
1.1.2.2 Alaskan Aviation Weather Unit (AAWU)1-2
1.1.2.3 Center Weather Service Unit (CWSU)1-3
1.1.2.4 Weather Forecast Office (WFO)1-3
1.1.2.5 NWS Office at the FAA Academy1-3
1.2 FEDERAL AVIATION ADMINISTRATION (FAA)1-4
1.2.1 Air Traffic Control System Command Center (ATCSCC)1-4
1.2.2 Air Route Traffic Control Center (ARTCC)1-4
1.2.3 Air Traffic Control Tower (ATCT) and Terminal Radar Approach Control (TRACON)1-4
1.2.4 Flight Service Station (FSS) / Automated Flight Service Station (AFSS)1-5
1.3 DISSEMINATION OF AVIATION WEATHER PRODUCTS1-6
1.3.1 Weather Briefings1-6
1.3.1.1 Standard Briefing1-6
1.3.1.2 Abbreviated Briefing1-7
1.3.1.3 Outlook Briefing1-7
1.3.2 Direct Use Access Terminal Service (DUATS/DUAT)1-7
1.3.3 Aviation Digital Data Service (ADDS)1-8
1.3.4 Telephone Information Briefing Service (TIBS)1-8
1.3.5 Hazardous Inflight Weather Advisory Service (HIWAS)1-9
1.3.6 En Route Flight Advisory Service (EFAS)1-10
1.3.7 Automatic Dependent Surveillance – Broadcast (ADS-B)1-11
1.3.7.1 Flight Information Service – Broadcast (FIS-B)1-11
1.3.7.1.1 FIS-B Products1-11
1.3.7.1.2 Operational Use of FIS-B Products1-12
2 AVIATION WEATHER PRODUCT CLASSIFICATION AND POLICY2-1
2.1 CLASSIFICATION OF AVIATION WEATHER PRODUCTS2-1
2.1.1 Primary Weather Product Classification2-1
2.1.2 Supplementary Weather Product Classification2-1
2.2 TYPES OF AVIATION WEATHER INFORMATION2-2
2.2.1 Observations2-2
2.2.2 Analysis2-2
2.2.3 Forecasts2-2
2.3 CATEGORIZING AVIATION WEATHER SOURCES2-2
2.3.1 Federal Government2-2
2.3.2 Enhanced Weather Information System (EWINS)2-3
2.3.3 Commercial Weather Information Providers2-3
3 OBSERVED TEXT PRODUCTS3-1
3.1 AVIATION ROUTINE WEATHER REPORTS (METAR) AND AVIATION SELECTED SPECIAL WEATHER
REPORTS (SPECI)3-1
3.1.1 Aviation Routine Weather Report (METAR)3-1
3.1.2 Aviation Selected Special Weather Report (SPECI)3-1
Table 3-1. SPECI Criteria3-2
3.1.3 Format3-3
Figure 3-1. METAR/SPECI Coding Format3-3
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) Page ii Table of Contents
3.1.3.1 Type of Report3-3
3.1.3.2 Station Identifier3-3
Figure 3-2. ICAO Continent codes3-4
3.1.3.3 Date and Time of Report3-5
3.1.3.4 Report Modifier (As Required)3-5
3.1.3.5 Wind Group3-6
3.1.3.5.1 Wind Gust3-6
3.1.3.5.2 Variable Wind Direction (speed 6 knots or less)3-6
3.1.3.5.3 Variable Wind Direction (speed greater than 6 knots)3-6
3.1.3.5.4 Calm Wind3-7
3.1.3.6 Visibility Group3-7
3.1.3.7 Runway Visual Range (RVR) Group3-7
3.1.3.8 Present Weather Group3-8
Table 3-2. METAR/SPECI Notations for Reporting Present Weather13-9
3.1.3.8.1 Intensity Qualifier3-10
3.1.3.8.2 Proximity Qualifier3-10
3.1.3.8.3 Descriptor Qualifier3-10
3.1.3.8.4 Precipitation3-11
3.1.3.8.5 Obscuration3-11
3.1.3.8.6 Other Weather Phenomena3-11
3.1.3.9 Sky Condition Group3-12
Figure 3-3. Obscuration Effects on Slant Range Visibility3-12
Table 3-3. METAR/SPECI Contractions for Sky Cover3-13
Table 3-4. METAR/SPECI Increments of Reportable Values of Sky Cover Height3-13
Figure 3-4. METAR/SPECI Sky Condition Coding3-14
3.1.3.10 Temperature/Dew Point Group3-15
3.1.3.11 Altimeter3-15
3.1.3.12 Remarks (RMK)3-15
Table 3-5. METAR/SPECI Order of Remarks3-16
3.1.3.13 Automated, Manual, and Plain Language Remarks3-17
3.1.3.13.1 Volcanic Eruptions (Plain Language)3-17
3.1.3.13.2 Funnel Cloud3-17
3.1.3.13.3 Type of Automated Station3-17
3.1.3.13.4 Peak Wind3-17
3.1.3.13.5 Wind Shift3-18
3.1.3.13.6 Tower or Surface Visibility3-18
3.1.3.13.7 Variable Prevailing Visibility3-18
3.1.3.13.8 Sector Visibility (Plain Language)3-18
3.1.3.13.9 Visibility at Second Location3-18
3.1.3.13.10 Lightning3-18
Table 3-6. METAR/SPECI Type and Frequency of Lightning3-19
3.1.3.13.11 Beginning and Ending of Precipitation3-19
3.1.3.13.12 Beginning and Ending of Thunderstorms3-19
3.1.3.13.13 Thunderstorm Location (Plain Language)3-19
3.1.3.13.14 Hailstone Size (Plain Language)3-19
3.1.3.13.15 Virga (Plain Language)3-20
3.1.3.13.16 Variable Ceiling Height3-20
3.1.3.13.17 Obscurations (Plain Language)3-20
3.1.3.13.18 Variable Sky Condition (Plain Language)3-20
3.1.3.13.19 Significant Cloud Types (Plain Language)3-20
3.1.3.13.19.1 Cumulonimbus or Cumulonimbus Mammatus3-20
Figure 3-5. Cumulonimbus (CB) Example3-21
Figure 3-6. Cumulonimbus Mammatus (CBMAM) Example3-21
3.1.3.13.19.2 Towering Cumulus3-22
Figure 3-7. Towering Cumulus (TCU) Example3-22
3.1.3.13.19.3 Altocumulus Castellanus3-23
Figure 3-8. Altocumulus Castellanus (ACC) Example3-23
3.1.3.13.19.4 Standing Lenticular or Rotor Clouds3-24
Figure 3-9. Standing Lenticular and Rotor Clouds Example3-24
3.1.3.13.20 Ceiling Height at Second Location3-24
3.1.3.13.21 Pressure Rising or Falling Rapidly3-25
3.1.3.13.22 Sea-Level Pressure3-25
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) Table of Contents Page iii
3.1.3.13.23 Aircraft Mishap (Plain Language)3-25
3.1.3.13.24 No SPECI Reports Taken (Plain Language)3-25
3.1.3.13.25 Snow Increasing Rapidly3-25
3.1.3.13.26 Other Significant Information (Plain Language)3-25
3.1.3.14 Additive and Automated Maintenance Data3-25
3.1.3.14.1 Hourly Temperature and Dew Point3-25
3.1.3.14.2 Maintenance Data Groups3-26
3.1.3.14.2.1 Sensor Status Indicators3-26
3.1.3.14.2.2 Maintenance Indicator3-26
3.1.4 METAR/SPECI Examples3-27
3.2 PILOT WEATHER REPORTS (PIREP)3-32
3.2.1 Format3-32
Figure 3-10. Pilot Weather Report (PIREP) Coding Format3-32
3.2.1.1 Message Type (UUA/UA)3-32
3.2.1.1.1 Urgent PIREPs3-32
3.2.1.1.2 Routine PIREPs3-33
3.2.1.2 Location (/OV)3-33
3.2.1.2.1 Location3-33
3.2.1.2.1.1 Route Segment3-33
3.2.1.3 Time (/TM)3-34
3.2.1.4 Altitude/Flight Level (/FL)3-34
3.2.1.5 Aircraft Type (/TP)3-34
3.2.1.6 Sky Condition (/SK)3-34
3.2.1.7 Flight Visibility and Weather (/WX)3-35
Table 3-7. PIREP Weather Type and Symbols3-36
3.2.1.8 Air Temperature (/TA)3-38
3.2.1.9 Wind Direction and Speed (/WV)3-38
3.2.1.10 Turbulence (/TB)3-38
Table 3-8. PIREP Turbulence Reporting Criteria3-39
3.2.1.11 Icing (/IC)3-39
Table 3-9. Icing Intensities, Contractions, and Airframe Ice Accumulation3-40
Table 3-10. Icing Types, Contractions, and Descriptions3-40
3.2.1.12 Remarks (/RM)3-40
3.2.1.12.1 Wind Shear3-41
3.2.1.12.2 FUNNEL CLOUD, TORNADO, and WATERSPOUT3-41
3.2.1.12.3 Thunderstorm3-41
3.2.1.12.4 Lightning3-41
3.2.1.12.5 Electrical Discharge3-41
3.2.1.12.6 Clouds3-42
3.2.1.12.7 Plain Language3-42
3.2.1.12.8 Volcanic Eruptions3-42
3.2.1.12.9 SKYSPOTTER3-42
3.2.2 PIREP Examples3-43
3.3 RADAR WEATHER REPORT (SD/ROB)3-45
Figure 3-11. Radar Weather Report (SD/ROB) Coding Format3-45
3.3.1 Format3-45
3.3.1.1 Location Identifier3-45
3.3.1.2 Time3-45
3.3.1.3 Configuration3-45
Figure 3-12. Radar Weather Report (SD/ROB) Configurations3-46
3.3.1.4 Coverage3-46
3.3.1.5 Precipitation Type3-46
3.3.1.6 Precipitation Intensity3-47
Table 3-11. SD/ROB Reportable Intensities3-47
3.3.1.7 Location3-47
Figure 3-13. SD/ROB AREA, Line (LN), and CELL Location Examples3-48
3.3.1.8 Maximum Top3-48
3.3.1.9 Cell Movement3-48
3.3.1.10 Remarks3-49
Table 3-12. Weather Radar Report Remarks and Meaning3-49
3.3.1.11 Digital Section3-49
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) Page iv Table of Contents
Figure 3-14. SD/ROB Digital Section Information Plotted on a PPI Grid Overlay Example3-50
3.3.2 Examples3-50
Figure 3-15. WSR-88D Weather Radar Network Sites3-52
4 RADAR AND SATELLITE IMAGERY4-1
4.1 RADAR4-1
4.1.1 Description4-1
4.1.2 Modes of Operation4-1
4.1.2.1 Clear Air Mode4-1
4.1.2.2 Precipitation Mode4-1
4.1.3 Echo Intensities4-2
Figure 4-1. WSR-88D Weather Radar Echo Intensity Legend4-2
Table 4-1. WSR-88D Weather Radar Precipitation Intensity Terminology4-2
4.1.4 Products4-3
4.1.4.1 Base Reflectivity4-3
Figure 4-2. WSR-88D Weather Radar Short Range (124 NM) Base Reflectivity Product Example
.4-3
Figure 4-3. WSR-88D Weather Radar Long Range (248 NM) Base Reflectivity Product Example 4- 4
4.1.4.1.1 Base Reflectivity Use4-4
Figure 4-4. WSR-88D Weather Radar Stratiform Precipitation on the 0.5ºBase Reflectivity
Product Example4-5
Figure 4-5. WSR-88D Weather Radar Convective Precipitation on the 0.5ºBase Reflectivity
Product Example4-5
4.1.4.1.2 Strengths of Base Reflectivity4-6
4.1.4.1.3 Limitations of Base Reflectivity4-6
4.1.4.1.3.1 Radar Beam Overshooting4-6
4.1.4.1.3.2 Beam Blockage4-6
Figure 4-6. WSR-88D Weather Radar Beam Blockage on Base Reflectivity Product Example ... 4-7
4.1.4.1.3.3 Ground Clutter4-7
Figure 4-8. WSR-88D Weather Radar Ground Clutter Example4-7
4.1.4.1.3.4 Ghost4-8
Figure 4-9. WSR-88D Weather Radar Ghost Example4-8
4.1.4.1.3.5 Angels4-8
Figure 4-10. WSR-88D Weather Radar Angle Example4-9
4.1.4.1.3.6 Anomalous Propagation (AP)4-9
Figure 4-11. WSR-88D Weather Radar Anomalous Propagation (AP) Example4-10
4.1.4.2 Composite Reflectivity4-10
Figure 4-12. Creation of a Composite Reflectivity product4-10
Figure 4-13. WSR-88D Weather Radar Short Range (124 NM) Composite Reflectivity Product
Example4-11
4.1.4.2.1 Composite Reflectivity Use4-11
Figure 4-14. WSR-88D Weather Radar 0.5º Base Reflectivity versus Composite Reflectivity
Comparison4-12
4.1.4.2.2 Strengths of Composite Reflectivity4-12
4.1.4.2.3 Limitations of Composite Reflectivity4-12
4.1.4.2.3.1 Radar Beam Overshooting4-12
4.1.4.2.3.2 Beam Blockage4-12
4.1.4.2.3.3 Ground Clutter4-13
4.1.4.2.3.4 Ghost4-13
4.1.4.2.3.5 Angels4-13
4.1.4.2.3.6 Anomalous Propagation (AP)4-13
4.1.5 Radar Mosaics4-13
4.1.5.1 0.5º Mosaics - Contiguous U.S. and Hawaii4-14
Table 4-2. NWS Radar Mosaic Products4-14
Figure 4-15. Great Lakes Regional Radar Mosaic Example4-14
4.1.5.2 0.5º Mosaics - Alaska4-15
Figure 4-16. Alaskan Regional Radar Mosaic Example4-15
4.2 SATELLITE4-16
4.2.1 Description4-16
4.2.2 Imagery Types4-16
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) Table of Contents Page v
4.2.2.1 Visible Imagery4-16
Figure 4-17. Visible Satellite Image – U.S. Example4-17
Figure 4-18. Visible Satellite Image – Regional-Scale Example4-18
4.2.2.1.1 Visible Image Data Legend4-18
Figure 4-19. Visible Satellite Data Legend4-18
4.2.2.2 Infrared (IR) Imagery4-18
Figure 4-20. Infrared (Color) Satellite Image – U.S. Example4-19
Figure 4-21. Infrared (Color) Satellite Image – Regional-Scale Example4-20
Figure 4-22. Unenhanced Infrared (black and white) Satellite Image – U.S. Example4-20
Figure 4-23. Unenhanced Infrared (black and white) Satellite Image – Regional- Scale Example . 4- 21
4.2.2.2.1 Infrared Image Data Legends4-21
Figure 4-24. Infrared (Color) Satellite Image Data Legend4-21
Figure 4-25. Unenhanced Infrared (black and while) Satellite Image Data Legend4-21
4.2.3.3 Water Vapor Imagery4-21
Figure 4-26. Water Vapor Satellite Image – U.S. Example4-22
Figure 4-27. Water Vapor Satellite Image – Regional-Scale Example4-23
4.2.3.3.1 Water Vapor Image Data Legend4-23
Figure 4-28. Water Vapor Satellite Image Data Legend4-23
5 GRAPHICAL OBSERVATIONS AND DERIVED PRODUCTS5-1
5.1 SURFACE ANALYSIS CHARTS5-1
Figure 5-1. HPC Surface Analysis Chart Example5-1
5.1.1 Issuance5-1
5.1.2 HPC Surface Analysis Charts5-2
5.1.2.1 Issuance5-2
Table 5-1. HPC Surface Analysis Charts Issuance Schedule5-2
5.1.2.2 Analysis Symbols5-2
Figure 5-2. HPC Surface Analysis Chart Symbols5-3
5.1.2.3 Station Plot Models5-3
Figure 5-3. HPC Surface Analysis Chart Station Plot Model5-3
Figure 5-4. HPC Surface Analysis Chart Ship/Buoy Plot Model5-4
Figure 5-5. HPC Surface Analysis Chart for Aviation Interests Station Plot Model5-4
5.1.2.3.1 Station Identifier5-4
5.1.2.3.2 Temperature5-4
5.1.2.3.3 Dew Point5-5
5.1.2.3.4 Weather5-5
Figure 5-6. HPC Surface Analysis Chart Common Weather Symbols5-5
5.1.2.3.5 Wind5-5
Figure 5-7. HPC Surface Analysis Chart Wind Plotting Model5-6
5.1.2.3.6 Ceiling5-6
5.1.2.3.7 Visibility5-6
5.1.2.3.8 Pressure5-6
5.1.2.3.9 Pressure Trend5-6
Figure 5-8. HPC Surface Analysis Chart Pressure Trends5-7
5.1.2.3.10 Sky Cover5-7
Figure 5-9. HPC Surface Analysis Chart Sky Cover Symbols5-7
5.1.2.3.11 Water Temperature5-7
5.1.2.3.12 Swell Information5-8
5.1.2.3.13 Wave Information5-8
5.1.2.4 Analyses5-8
5.1.2.4.1 Isobars5-8
5.1.2.4.2 Pressure Systems5-9
5.1.2.4.3 Fronts5-9
Figure 5-10. HPC Surface Analysis Chart – North America Example5-9
Figure 5-11. HPC Surface Analysis Chart - Contiguous U.S. Example5-10
Figure 5-12. HPC Surface Analysis Chart - Northeast U.S. Example5-10
Figure 5-13. HPC Surface Analysis Chart for Aviation Interests – Contiguous U.S. Example .. 5-11 Figure 5-14. HPC Surface Analysis Chart for Aviation Interests – South central U.S. Example 5-11
5.1.3 OPC and WFO Honolulu Surface Analysis Charts5-12
5.1.3.1 Issuance5-12
Aviation Weather Services, Advisory Circular 00-45G, Change 1 (July 2010) Page vi Table of Contents
Table 5-2. OPC and WFO Honolulu Surface Analysis Charts Issuance Schedule5-12
5.1.3.2 Analysis Symbols5-12
Figure 5-15. OPC and WFO HNL Surface Analysis Chart Symbols5-12
Figure 5-16. WFO HNL Surface Analysis Chart – North Pacific Example5-13
5.1.3.3 Wave Information5-13
5.1.3.4 Analyses5-13
5.1.3.4.1 Isobars5-13
5.1.3.4.2 Pressure Systems5-14
5.1.3.4.3 Fronts5-14
5.1.4 TPC Surface Analysis Charts5-14
5.1.4.1 Issuance5-14
Table 5-3. TPC Surface Analysis Charts Issuance Schedule5-14
5.1.4.2 Analysis Symbols5-14
Figure 5-17. TPC Surface Analysis Chart Symbols5-15
Figure 5-18. TPC Tropical Surface Analysis Chart Example5-15
5.1.4.2.1 Wind5-15
Figure 5-19: TPC Surface Analysis Chart Wind Plotting Model5-16
5.1.4.3 Analyses5-16
5.1.4.3.1 Isobars5-16
5.1.4.3.2 Pressure Systems5-16
5.1.4.3.3 Fronts5-17
5.1.5 Unified Surface Analysis Chart5-17
5.1.5.1 Issuance5-17
Table 5-4. Unified Surface Analysis Chart Issuance Schedule5-17
Figure 5-20. Unified Surface Analysis Chart Example5-17
5.1.5.2 Analysis Symbols5-17
Figure 5-21. Unified Surface Analysis Chart Symbols5-18
5.1.5.3 Analyses5-18
5.1.5.3.1 Isobars5-18
5.1.5.3.2 Pressure Systems5-18
5.1.5.3.3 Fronts5-18
5.1.6 AAWU Surface Charts5-19
5.1.6.1 Issuance5-19
Table 5-5. AAWU Surface Analysis Issuance Schedule5-19
5.1.6.2 Analysis Symbols5-19
Figure 5-22. AAWU Surface Analysis Chart Symbols5-19
Figure 5-23. AAWU Alaskan Surface Chart Example5-20
5.1.6.3 Station Plot Models5-20
Figure 5-24. AAWU Surface Analysis Chart Station Plot Model5-20
Figure 5-25. AAWU Surface Analysis Chart Ship/buoy Plot Model5-21
5.1.6.3.1 Station Identifier5-21
5.1.6.3.2 Temperature5-21
5.1.6.3.3 Dew Point5-21
5.1.6.3.4 Wind5-21
Figure 5-26: AAWU Surface Analysis Chart Wind Plotting Model5-22
5.1.6.3.5 Ceiling5-22
5.1.6.3.6 Visibility5-22
5.1.6.3.7 Pressure5-22
5.1.6.3.8 Pressure Trend5-22
Figure 5-27. AAWU Surface Analysis Chart Pressure Trends5-23
5.1.6.3.9 Sky Cover5-23
Figure 5-28. AAWU Surface Analysis Chart Sky Cover Symbols5-23
5.1.6.3.10 Water Temperature5-23
5.1.6.3.11 Swell Information5-24
5.1.6.3.12 Wave Information5-24
5.1.6.4 Analyses5-24
5.1.6.4.1 Isobars5-24
5.1.6.4.2 Pressure Systems5-24
5.1.6.4.3 Fronts5-25
5.2 CONSTANT PRESSURE CHARTS5-26
Figure 5-29. Constant Pressure Chart Example5-26
5.2.1 Issuance5-26