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5.8.2.4 VAA Graphic Example.
Figure 5-34. Volcanic Ash Advisory in Graphical Format
5.9 G raphical Forecast for Aviation (GFA).
The GFAs are a set of Web-based displays which are expected to provide the necessary aviation weather information to give users a complete picture of the weather that may impact flights in the CONUS. These displays are updated continuously and provide forecasts, observational data, and warnings of weather phenomena that can be viewed from 14 hours in the past to 15 hours in the future. This product covers the surface up to FL420 (or 42,000 ft MSL). Wind, icing, and turbulence forecasts are available in 3,000-ft increments from the surface up to 18,000 ft MSL, and in 6,000-ft increments from 18,000 ft MSL to FL420. Turbulence forecasts are also broken into low (below 18,000 ft MSL) and high (above 18,000 ft MSL) graphics. A maximum icing graphic and maximum wind velocity graphic (regardless of altitude) are also available. The graphic below is an example of an aviation forecast for clouds.
Figure 5-35. Aviation Forecast for Clouds-Example Aviation Forecasts • Clouds SURVEY INFO CIG/VIS PCPN/WX +3hr 2300 UTC Mon 13 Jun 2016 Obs/Warn Settings 00Z 012 02Z 032 042 052 062 072 082 092 10Z TOP 090 OVC080 o BKNOO TOP O05 LYRD. LY 0079 avE CI ABV CI AB TOP 090 OVCOZO OVC110
• I 5 TO 02 10015 TO Scale C085 TOF 020 Cirrus 500 km Ans Cirrus ONC 500 mi VERAP Cloud Fraction at Low [20160613_18_F05] Coverage <FL180 SKY FEW SCT BKN OVC SKY Coverage Below FL180) OSKC OFEW OSCT OBKN •ovC AIRMETS OBSCN MInOR MTN SIGMETS SI Thunder Storm Cyclonel Trop Volcanic Ash
5.9.1 Time Selection and Slider.
Available weather product tabs are configured based on the time selection. Users may choose between Forecast and Observations/Warnings (Obs/Warn). The specific hour may then be chosen by the time slider.
Figure 5-36. Time Selection and Slider orecast Obs/Warn Settings 162 17Z 18Z 19Z 20Z 21Z 22Z 23Z 00Z 01Z 02Z 03Z 04Z 05Z 06Z
5.9.1.1 Forecast Weather Products Tabs.
Weather products with forecast information are available by selecting one of the tabs at the top of the display above the time selector. The selected product will be highlighted. The default is TAF.
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5-63 Figure 5-37. Forecast Weather Products Tabs
5.9.1.2 Forecast Weather Product Elements Tabs.
The following table shows which weather elements are displayed on each forecast product tab. The acronyms in this table are decoded for each product by clicking the products tab to review the NWS Hazard and Code and the AWC SIGMET and Code charts found at https://www.aviationweather.gov/gf a/help?page=products.
Table 5-11. Weather Elements on Forecast Product Tabs Product Gridded Product Weather Data Overlay SIGMET NWS Warnings AIRMET Vertical Levels TAF - - All All - - CIG/VIS LAMP Flight Category, Ceiling, or Visibility NDFD Precipitation/ Weather Type and Intensity Symbol
C-SIG TC TS BD BS VA WS BZ Sierra (IFR) - Clouds RAP Model Cloud Coverage, Tops, or Bases RAP Model Cloud Base, Layers, and Tops C-SIG TC TS VA - Mountain Obscuration -
PCPN/WX NDFD Precipitation/ Weather Type and Likelihood NDFD Precipitation/ Weather Type and Intensity
C-SIG TC TS BD BS VA
TO TS WS BZ
IS LS ST
- -
TS NDFD Thunderstorm Coverage NDFD Thunderstorm Type and Intensity
C-SIG TC TS TO TS - - Winds RAP/NDFD Wind Speed RAP/NDFD Wind and Gust Barb
C-SIG TC TS WS BZ IS ST GA HW LLWS, Strong Surface Winds
SFC, MAX, every 3,000 ft from FL030 to FL300; every 6,000 ft from FL300 to FL480 Turb Graphical Turbulence Guidance (GTG)
- C-SIG TC TS TB - Turbulence LO, HI, every 3,000 ft from FL030 to FL300; every 6,000 ft from FL300 to FL480
5-64 Product Gridded Product Weather Data Overlay SIGMET NWS Warnings AIRMET Vertical Levels Ice FIP @ “SFC” NDFD Winter Precipitation/ Weather Type and Likelihood @ “SFC” NDFD Winter Precipitation/ Weather Type and Intensity C-SIG TC TS IC @ “SFC” WS
BZ IS LS Icing SFC, MAX, every 3,000 ft from FL030 to FL300; every 6,000 ft from FL300 to FL480
5.9.1.3 Observations/Warnings (Obs/Warn).
The Observation/Warning option provides an option to display weather data for the current time and the previous fourteen hours (rounded to the nearest hour). Users may advance through time using the arrow buttons or by clicking on the desired hour.
Figure 5-38. Observations/Warnings Tab
5.9.1.4 Observations/Warnings Weather Product Tabs.
The following table shows what is displayed on each Observations/Warnings weather product tab. Each product in this menu is overlaid on an infrared (IR) satellite image with a radar loop of the five most recent images up to the selected hour.
Table 5-12. Products Displayed on Observations/Warnings Weather Products Tab Product Weather Data Overlay SIGMET NWS Warnings Vertical Levels METAR METAR Station Plot All All - PCPN/WX METAR Precipitation Weather Symbol
C-SIG TC TS BD BS VA
TO TS WS BZ IS LS ST - CIG/VIS FLT CAT: Non-VFR Color-Coded METAR Flight Category Symbol CIG: Number (ft/100) VIS: Number (SM)
C-SIG TC TS BD BS VA
WS BZ - PIREP PIREP symbols All - ALL, every 3,000 ft from FL030 to FL300;
every 6,000 ft from FL300 to FL480 RAD/SAT - All All -
5.9.2 GFA Static Images.
Some users with limited Internet connectivity may access static images via the AWC at https://www.aviationweather.gov/gfa/plot. There are two static graphical images
5-65 available titled, “Aviation Cloud Forecast” and “Aviation Surface Forecast.” The Aviation Cloud Forecast provides cloud coverage, bases, layers, and tops with AIRMET Sierra for mountain obscuration and AIRMET Zulu for icing overlaid. The Aviation Surface Forecast provides visibility, weather phenomena, and winds (including wind gusts) with AIRMET Sierra for IFR conditions and AIRMET Tango for sustained surface winds of 30 kts or more overlaid. These images are presented on 10 separate maps providing forecast views for the entire CONUS on one, and 9 regional views which provide more detail for the user. They are updated every 3 hours and provide forecast snapshots for 3, 6, 9, 12, 15, and 18 hours in the future.
Figure 5-39. GFA Static Cloud Forecast
5-66 Figure 5-40. GFA Surface Forecast
5.9.3 Strengths and Limitations (GFA).
5.9.3.1 Strengths.
• One-stop shop for multiple data fields.
• Focused on low-altitude flights common to GA community.
• Simplified display for non-meteorologist users.
• Available 24 hours a day, 7 days a week.
• Updated continuously.
• Resolution of 2.2 km.
• Available 6 hours in the past up to 15 hours in the future.
5.9.3.2 Limitations.
Caution should be applied as users configure the GFA for use. Users can turn on and turn off certain functions, i.e., AIRMET’s and SIGMET’s overlays for a given geographical area. This can lead to hidden areas of hazardous weather for a given flight path.
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5.9.4 Recommended Action for Users.
5.9.4.1 For more information on how to use this product, all users are encouraged to visit the GFA interactive web tool at https://www.aviationweather.gov/gfa.
5.9.4.2 A short video explaining how to navigate the GFA can be found at https://www.youtube.com/watch?v=kLe6Eu3fwS0.
5.9.4.3 Users may provide feedback for the Aviation Surface Forecast and the Aviation Cloud Forecast graphics at https://www.aviationweather.gov/ areafcst.
5.10 Localized Aviation Model Output Statistics (MOS) Program (LAMP).
The LAMP weather product is a statistical model program that provides specific point forecast guidance on sensible weather elements (perceivable elements such as temperature, wind, sky cover, etc.). LAMP weather product forecasts are provided in both graphical and coded text format, and are currently generated for more than 1,500 locations. The LAMP weather product is entirely automated and may not be as accurate as a forecast generated with human involvement. However, information from the LAMP weather product can be used in combination with Terminal Aerodrome Forecasts (TAF), and other weather reporting and forecasting products and tools, to provide additional information and enhance situational awareness regarding a particular location.
5.10.1 Strengths and Limitations (LAMP).
5.10.1.1 Strengths.
• Updated hourly, incorporating the latest surface conditions to produce hourly forecasts of weather elements reaching up to 25 hours in the future.
• Users can access fresh forecast information for the next 24 hours.
• Provides both categorical and probabilistic forecast guidance on various elements, allowing users to extract the type of information they want.
• Categorical ceiling/visibility forecast information is presented, along with forecasts dependent on the occurrence of precipitation. This data attempts to account for some of the temporary fluctuations that occur in flight.
5.10.1.2 Limitations.
May not be as accurate as a forecast generated with human involvement.
5.10.2 Recommended Action for Users.
• A list of LAMP airports can be found at http://www.nws.noaa.gov/mdl/gfslamp/gfslamp.shtml.
5-68 Note: Once you have selected the above link, look at the left-side menu under “Text Forecasts” and select “By Station” to get a list of the LAMP stations by state.
• A detailed descriptio n of the LAMP can be accessed at http://www.nws.noaa.gov/mdl/gfslamp/docs/LAMP_description.shtml.
• The NOAA/NWS LAMP home page can be accessed at http://www.nws.noaa.gov/mdl/lamp/index.shtml.
5.11 Area Forecasts (FA).
An FA is an abbreviated plain language forecast concerning the occurrence or expected occurrence of specified en route weather phenomena. The FA (in conjunction with AIRMETs, SIGMETs, Convective SIGMETs, CWAs, etc.) is used to determine forecast en route weather over a specified geographic region. FAs cover an 18- to 24-hour period, depending on the region, and issued three to four times daily, depending on the region, and are updated as needed. The exact phenomenon contained in FAs also varies by region.
FAs are not intended for use as a substitute for a TAF for those air carrier operations that require weather forecasts at specific airports (i.e., origin, destination, and any alternate).
In these operations, a TAF or equivalent forecast that is generated for the specific airport in question, is required to meet the 14 CFR regulatory requirements that specify certain weather conditions and minima at the origin, destination, and alternate airports.
5.11.1 FA—Gulf of Mexico, Caribbean, Hawaii, and Alaska.
5.11.1.1 FA Issuance.
The following offices issue FAs for the following areas:
• The AWC:
o Gulf of Mexic o: The northern Gulf of Mexico, including the Houston Oceanic FIR, the Gulf of Mexico portion of the Miami Oceanic FIR, and the coastal waters west of 85W longitude (see Figure 5-41, AWC Area Forecast (FA) Region and WMO Header—Gulf of Mexico).
o Caribbean Sea: Portions of the Gulf of Mexico (south of the Houston Oceanic FIR to approximately 22N latitude), the Caribbean Sea, and adjacent portions of the North Atlantic (see Figure 5-42, AWC Area Forecast (FA) Region and WMO Header—Caribbean).
o Hawaii: The main Hawaiian Islands and adjacent coastal waters extending out 40 NM from the coastlines (see Figure 5-43, WFO Honolulu Area Forecast (FA) Region and WMO Header— Hawaii ).
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• The AAWU:
o Alaska: S even FAs containing a total of 25 zones (see Table 5-11, Weather Elements on Forecast Product Tabs), covering separate geographic al areas of Alaska and the adjacent coastal waters, including the Pribilof Islands and Southeast Bering Sea (see Figure 5-44, AAWU Flight Advisory and Area Forecast (FA) Zones—Alaska).
Figure 5-41. AWC Area Forecast (FA) Region and WMO Header—Gulf of Mexico
5-70 Figure 5-42. AWC Area Forecast (FA) Region and WMO Header—Caribbean
F igure 5-43. WFO Honolulu Area Forecast (FA) Region and WMO Header—Hawaii
5-71 Figure 5-44. AAWU Flight Advisory and Area Forecast Zones—Alaska
Tabl e 5-13. AAWU Area Forecast (FA) Zones—Alaska 1 Arctic Coast Coastal 2 North Slopes of the Brooks Range 3 Upper Yukon Valley 4 Koyukuk and Upper Kobuk Valley 5 Northern Seward Peninsula-Lower Kobuk Valley 6 Southern Seward Peninsula-Eastern Norton Sound 7 Tanana Valley 8 Lower Yukon Valley 9 Kuskowim Valley 10 Yukon-Kuskowim Delta 11 Bristol Bay 12 Lynn Canal and Glacier Bay 13 Central Southeast Alaska 14 Southern Southeast Alaska 15 Coastal Southeast Alaska 16 Eastern Gulf Coast 17 Copper River Basin 18 Cook Inlet-Susitna Valley 19 Central Gulf Coast 20 Kodiak Island 21 Alaska Peninsula-Port Heiden to Unimak Pass 22 Unimak Pass to Adak 23 St. Lawrence Island-Bering Sea Coast 24 Adak to Attu 25 Pribilof Islands and Southeast Bering Sea
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5.11.1.2 FA Standardization.
All FAs follow these standards:
• All heights or altitudes are referenced to MSL, unless otherwise noted
(i.e., prefaced by AGL or CIG), and annotated using the height in hundreds of feet, consisting of three digits (e.g., 040). For heights at or above 18,000 ft, the level is preceded by FL to represent FLs
(e.g., FL180). Tops are always referenced to MSL.
• References to latitude and longitude are in whole degrees and minutes following the model: Nnn[nn] or Snn[nn], Wnnn[nn], or Ennn[nn] with a space between latitude and longitude and a hyphen between successive points. Example: N3106 W07118 – N3011 W7209.
• Messages are prepared in abbreviated plain language using contractions from Order 7340.2 for domestic products and ICAO Document 8400 for products issued for Oceanic FIRs. A limited number of non-abbreviated words, geographical names, and numerical values of a self-explanatory nature may also be used.
• Weather and obstructions to visibility are described using the weather abbreviations for surface weather observations (METAR/SPECI).
5.11.1.3 FA Issuance Schedule.
FAs are scheduled products issued at the following times (see Table 5-14, Area Forecast (FA) Issuance Schedule).
Table 5-14. Area Forecast (FA) Issuance Schedule Gulf of Mexico (UTC) Caribbean (UTC) Hawaii (UTC) Alaska (UTC) 1st Issuance 0130 0330 0340 0415 (DT) 0515 (ST) 2nd Issuance 1030 0930 0940 1215 (DT) 1315 (ST) 3rd Issuance 1830 1530 1540 2015 (DT) 2115 (ST) 4th Issuance None 2130 2140 None Note: DT—During Alaska Daylight Time, ST—During Alaska Standard Time, UTC—Coordinated Universal Time.
5.11.1.4 FA Amendments.
Amendments are issued whenever the weather significantly improves or deteriorates based upon the judgment of the forecaster. AMD is included after the date/time group on the FAA product line. The date/time group on the WMO and FAA lines is updated to indicate the time of the correction. The ending valid time remains unchanged.