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Weather Products
The Graphical Forecasts for Aviation include gridded displays of various weather parameters as well as National Weather Service (NWS) textual weather observations, forecasts and warnings. Icing, turbulence, and wind gridded products are three-dimensional. Other gridded products are two-dimensional and may represent a “composite” of a three-dimensional weather phenomenon or a surface weather variable such as horizontal visibility. A list of NWS Hazards, AWC SIGMETs, and their associated codes is given below for reference:
| NWS Hazard | Code |
|---|---|
| Tornado | TO |
| Severe Thunderstorm | TS |
| Gale | GA |
| High Wind | HW |
| Lake Wind | LW |
| Wind | WN |
| Winter Weather | WW |
| Winter Storm | WS |
| Blizzard | BZ |
| Ice Storm | IS |
| Storm | ST |
| Freezing Rain | ZR |
| Lake Effect Snow | LS |
| Blowing Dust | BD |
| Small Craft for Winds | SCW |
| Dense Fog | DF |
| Freezing Fog | ZF |
| Marine Dense Fog | MDF |
| AWC SIGMET | Code |
|---|---|
| Convective | C-SIG |
| Tropical Cyclone | TC |
| International Thunderstorm |
TS |
| Volcanic Ash | VA |
| Blowing Dust/Sand | IFR |
| Turbulence | TB |
| Icing | IC |
Text information for relevant NWS textual weather observations and forecasts is available by clicking on the observation or warning, or by using the “hover” function selected in Settings. These data are either points of observed or forecast weather, often at airports, or regions of hazardous weather represented by two-dimensional polygons. Text boxes must be reselected after moving the time slider in order to update the information.
The default map shows the continental United States and coastal waters, but it can be panned in any direction and zoomed in or out by either using the "+/-" buttons in the upper left or the scroll wheel on the mouse.
It should be noted that the products that extend beyond the outlined region have been masked out for this page, and therefore does not indicate the absence of such phenomena in these areas.
Time Selection and Slider
Available weather product tabs are configured based on the time selection. Users may choose between Forecast and Observations/Warnings. The specific hour may then be chosen by the time slider.
Forecast
The Forecast option provides weather information for time starting one hour in the future (rounded to the nearest hour) to 18 hours in the future. Users may advance through time using the arrow buttons or by clicking directly on the desired hour.
Forecast Weather Product 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.
The following table shows which weather elements are displayed on each forecast product tab. A full description of these products and specific data configuration options are found in a subsection below.
| Product | SIGMET | NWS Warnings | AIRMET | Vertical Levels |
|---|---|---|---|---|
| TAF | All | All | – | – |
| CIG/VIS | C-SIG TC TS BD BS VA | WS BZ | Sierra (IFR) | – |
| Clouds | C-SIG TC TS VA | – | Mountain Obscuration | – |
| PCPN/WX | C-SIG TC TS BD BS VA | TO TS WS BZ IS LS ST | – | – |
| TS | C-SIG TC TS | TO TS | – | – |
| Winds | C-SIG TC TS | WS BZ IS ST GA HW | Low Level Wind Shear, Strong Surface Winds | SFC, MAX, every 3000 ft from FL030 to FL300, every 6000 ft from FL300 to FL480 |
| LLWS | – | – | Low Level Wind Shear | Below 2000 ft AGL |
| Turb | C-SIG TC TS TB | – | Turbulence | LO, HI, every 3000 ft from FL030 to FL300, every 6000 ft from FL300 to FL480 |
| Ice | C-SIG TC TS IC | @ "SFC" WS BZ IS LS | Icing | SFC, MAX, every 3000 ft from FL030 to FL300, every 6000 ft from FL300 to FL480 |
Terminal Aerodrome Forecast (TAF)
Station plots showing the TAF valid for the selected time are displayed in addition to all AWC SIGMET, NWS Warning polygons.
- Model data and imagery in blue
- G-AIRMET in purple
Ceiling & Visibility (CIG/VIS)
Model derived ceiling, visibility and flight category grids are displayed and each may be selected using the tabs in the upper left corner of the display. Flight Category is color-coded for MVFR, IFR and LIFR. Areas with VFR conditions are transparent. Ceiling grids are color-coded to show ceilings up to 3000 ft AGL, and Visibility displays color-coded grids for visibility up to 5 SM. Values above 3000 ft AGL or 5 SM visibility are transparent.
| Category | Ceiling | Visibility | |
|---|---|---|---|
| LIFR | below 500 feet AGL | and/or | less than 1 mile |
| IFR | 500 to below 1,000 feet AGL | and/or | 1 mile to less than 3 miles |
| MVFR | 1,000 to 3,000 feet AGL | and/or | 3 to 5 miles |
| VFR | greater than 3,000 feet AGL | and | greater than 5 miles |
AIRMET and SIGMET polygons that affect ceiling and/or visibility (volcanic ash, blowing dust/sand (IFR), convective, tropical cyclone, and international thunderstorm SIGMETs and AIRMET Sierra) are overlaid on the graphic. Select NWS Hazards are also displayed. These include Winter Storm, Blizzard, Blowing Dust, and Marine Dense Fog. Dense Fog and Freezing Fog will be added in the future.
Precipitation weather symbols are overlaid on the graphic.
Clouds
Model derived cloud fraction (few, scattered, broken, overcast) is displayed for clouds below FL180 each hour. Grid circles indicate the coverage at that particular location. The density of the grid circles increase as the user zooms in on the map. Text data displays layers and tops at each grid point. Cirrus or CI above indicate cirrus type clouds present above FL180.
NOTE: the color-coded grid and the grid circles are model-derived data. Users should check TAFs for forecast conditions.
Model bases and tops are available by selecting the tab in the upper left corner of the display. All color-coded grids and text information relays cloud heights above Mean Sea Level (MSL). Volcanic ash, convective, tropical cyclone, and international thunderstorm SIGMETs and AIRMETS for mountain obscuration are overlaid on the gridded display.
Precipitation / Weather (PCPN/WX)
A color-coded grid of weather type, severity, and likelihood is displayed to indicate forecast precipitation. The corresponding precipitation weather symbol is overlaid on the grid. Convective, tropical cyclone, international thunderstorm, and volcanic ash SIGMET polygons are automatically displayed. NWS hazards associated with precipitation including, tornado, severe thunderstorm, winter storm, winter weather, ice storm, freezing rain and lake effect snow are displayed.
| Code | Meaning |
|---|---|
| NoCov | No Coverage/probability |
| Sct | Scattered |
| Wide | Widespread |
| SChc | Slight Chance |
| Lkly | Likely |
| Patchy | Patchy |
| Iso | Isolated |
| Num | Numerous |
| Ocnl | Occasional |
| Chc | Chance of |
| Def | Definite |
| Areas | Areas of |
| Pds | Periods of |
| Inter | Intermittent |
| Frq | Frequent |
| Brf | Brief |
Thunderstorm (TS)
A grid of thunderstorm coverage categories (isolated, scattered, or numerous) is displayed with the thunderstorm type/intensity symbol overlaid. Convective, tropical cyclone, and international thunderstorm SIGMET polygons are displayed. Only Severe Thunderstorm and Tornado NWS warnings are included.
Severe Thunderstorm
A thunderstorm that produces a tornado, winds of at least 58 mph (50 knots or ~93 km/h), and/or hail at least 1" in diameter.
Winds
The user can select to view wind data for levels in 3000 ft. increments from the surface to FL300, and in 6000 ft. increments from FL300 to FL480. The user may also select to view data at the surface (SFC) or the maximum values (MAX) for all levels. Model wind speed is displayed in a color-coded graphic and wind speed and direction is depicted by gridded wind barbs, which increase in density as the user zooms in. Wind gusts are shown in red. When "MAX" is selected, the graphic displayed is the maximum value for wind speed and the associated direction wind barb regardless of flight level.
Convective, tropical cyclone, and international thunderstorm SIGMET and AIRMET Tango polygons for low level wind shear and strong surface winds are overlaid on the graphic. NWS wind advisories and warnings, which include Gale, Wind, High Wind, Lake Wind, Winter Storm, Blizzard, Ice Storm, Storm, and Blowing Dust are displayed at the surface. Small Craft warnings for wind will be added in the future.
Low Level Wind Shear
The Low Level Wind Shear (LLWS) tab displays the magnitude of non-convective wind shear below 2000 feet AGL. The wind shear values are a difference in wind speed (m/s) divided by the depth (m) of the shear layer, resulting in units of 1/s. Warmer colors, with values above around 0.12 /s, indicate areas with stronger wind shear. The LLWS tab also displays G-AIRMET polygons for low level wind shear.
Turbulence
The graphical turbulence grid is expressed in terms of Eddy Dissipation Rate (EDR). AIRMET Tango is displayed for turbulence only. It does not include AIRMET Tango for surface winds or low level wind shear. Turbulence, convective, tropical cyclone and international thunderstorm SIGMETs are also overlaid. The user can select flight levels in 3000 ft. increments between the surface and FL300, and in 6000 ft. increments between FL300 and FL480. The user also has the option to choose "LO" or "HI". When LO or HI is selected, the maximum EDR value is displayed for all altitudes below or at and above FL180, respectively. Likewise, only the LO or HI SIGMETs are displayed corresponding to the selected level.
| Aircraft Weight Class (Max Takeoff Weight) |
Estimated EDR Threshold * 100 | |||
|---|---|---|---|---|
| Light | Moderate | Severe | Extreme | |
| Light ( < 15,500 lbs e.g. Cessna 320, Piper Cub, LJ23 ) | 13 | 16 | 36 | 64 |
| Medium ( 15,500 – 300,000 lbs; e.g. A320, B737, Gulfstream ) | 15 | 20 | 44 | 79 |
| Heavy ( > 300,000 lbs; e.g. A330-A380, B747, B777 ) | 17 | 24 | 54 | 96 |
Ice
The icing graphic provides color-coded icing severity depictions at various altitudes. The icing severity product combines a multitude of weather observations (temperature, humidity, satellite, observed surface weather and pilot reports, radar data, etc.) to diagnose areas of expected trace, light, moderate, and heavy icing. The user can use the vertical slide bar to choose to display the product at 3000 ft. intervals up to FL300. From FL300 to FL480 icing severity is depicted at 6000 ft. intervals. Two-dimensional AIRMET Zulu and Icing, convective, tropical cyclone and international thunderstorm SIGMET polygons are overlaid on the graphic valid at the selected level. The user may also choose "MAX" to display the maximum icing severity for a location regardless of altitude and all AIRMET Zulu, and SIGMET polygons. When "SFC" is selected, the icing product is replaced by a graphical grid showing winter precipitation type and likelihood. The weather symbol denoting the winter precipitation type and intensity is overlaid on the graphic along with NWS winter storm, blizzard, freezing rain, lake effect snow, winter weather and freezing fog polygons.
Observations & Warnings (Obs/Warn)
The Obs/Warn 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.
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 satellite image with a radar loop of the most recent five images up to the selected hour. A full description of these products and specific data configuration options are found in a subsection below.
| 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 3000 ft from FL030 to FL300, every 6000 ft from FL300 to FL480 |
| RAD/SAT | – | All | All | – |
METAR
METAR station plots are overlaid on infrared satellite imagery and a radar loop. Flight category and cloud coverage is indicated by the colored dots surrounding the observation stations. All METARs, SIGMETs and National Weather Service (NWS) warnings that impact aviation are plotted. Imagery and observations can be configured under Settings. By clicking or hovering over the polygon or station plot, the user can view text information which displays the hazard name, the NWS Office that issued the warning, and the time the warning ends, or the full decoded METAR.
Precipitation / Weather (PCPN/WX)
Convective, tropical cyclone, and international thunderstorm SIGMET polygons are automatically displayed over the satellite image and radar loop. The METAR weather symbol is displayed; however, full METAR data can be obtained by clicking on the station or using the hover function. NWS hazards associated with precipitation including, tornado, severe thunderstorm, winter weather, winter storm, ice storm, freezing rain and lake effect snow are displayed.
Ceiling & Visibility (CIG/VIS)
An infrared satellite image and radar loop is displayed for the selected time. AIRMETs and SIGMETS that affect ceiling and/or visibility (volcanic ash, blowing dust/sand (IFR), convective, tropical cyclone, and international thunderstorm SIGMETs and AIRMET Sierra) are overlaid on the graphic. Select NWS Hazards are also displayed. These include Winter Storm, blizzard, blowing bust, and Marine Dense Fog. Dense Fog and Freezing Fog will be added in the future.
The user may select to view data relating to flight category, ceiling or visibility by selecting the appropriate tab in the upper left corner of the display. Flight Category is indicated by a color-coded circle for stations with MVFR, IFR and LIFR conditions. Areas with VFR are not shown. Ceiling and visibility is indicated by a numerical value over each METAR station. Ceiling is in units of ft/100 and visibility is in statute miles. Full text METAR data can be obtained by clicking on or hovering over the number.
Pilot Reports (PIREP)
PIREPs are overlaid on infrared satellite imagery and a radar loop valid for the time selected. The user can choose to display all PIREPs or only those valid within 3000 ft of a particular flight level, chosen with the vertical slider. Coded and decoded PIREP text information is available by clicking on the individual report or by using the hover function. All valid SIGMET polygons will also be displayed.
Radar & Satellite (RAD/SAT)
Infrared satellite imagery and a radar loop are displayed. All AWC SIGMET and NWS Hazard polygons are overlaid on the imagery.
Gridded data from the Geostationary Operational Environmental Satellite (GOES) Geostationary Lightning Mapper (GLM) can be viewed within the GFA domain by selecting the button in the upper left corner of the display. The GLM provides enhanced visualization of convection beyond the extent of ground-based observations for GOES East and West up to 55 deg N as shown below.
Graphical Products and Configuration Options
Satellite, radar, weather and map overlays may all be configured using the Map Options tab.
Satellite Imagery
The web page uses a global satellite mosaic constructed from the five geostationary satellites plus appropriate polar orbiter imagery. This resulting image is created every 30 minutes from available imagery.
There are three types of images available:
- Infrared - This is a 10 kilometer image where brighter grays show colder cloud temperatures. (Default)
- Visible - This is a 5 kilometer image showing visible reflection from clouds and ground surface. Consequently, these images will be black at night.
- Water Vapor - This is a 10 kilometer image where brighter grays show higher areas of water vapor. This is useful for showing jet stream and thunderstorms.
The images are then sliced up and provided through a progressive tile cache to optimize data transmission and image resolution. The user can select any of the three options and adjust the opacity of the image in the Settings menu.
Radar Mosaics
The GFA uses the MRMS radar mosaic produced by the NWS. The radar image combines over 140 radars into a single image. Additional post-processing is performed to remove some ground clutter and anomalous propagation (AP). The limitations of the radar such as blockage by mountains, lack of radar to radar overlap and over-processing of clutter and AP can cause the image to not show precipitation where there might be some.
The default image used is the Base or Lowest Angle (RALA) product. This only uses the reflectivity from the lowest scan of the nearest radar. This is a 1km image for the contiguous United States. The user may choose to view a composite radar image by clicking on the RADAR tab under the OBSERVATIONS menu within the Map Options tab. Radar opacity may also be adjusted by the user under the same menu.
The display incorporates the latest radar image plus the previous 4 into a loop of radar data showing progression of precipitation echoes. By moving the time slider into the past, the radar loop will always show the latest 5 images ending in the time shown in the slider box. The valid time of the radar image is displayed on the map.
Data Overlays
Data overlays offer not only a display of data but each feature can be clicked on to get more information. This includes the raw or decoded METARs and PIREPs, and textual information for SIGMETs, AIRMETs, and NWS Warnings. It should be noted that each feature on the display could overlap another feature making it non-selectable. To select that underlying feature, a layer or two might have to be turned off, or the user may need to zoom in.
METARs, TAFs, and Weather Symbols
The METAR observations and TAFs are plotted using the standard station model where temperature, dewpoint, winds, altimeter setting, weather, ceiling and visibility are displayed around the station location. The user can select to view the data in metric units or have it decoded.
Note: Variable winds will appear with a circle around the station and a wind barb pointing north showing wind speed and gust.
The data plotted comes from the latest available observation, including SPECIs. If the time slider is moved into the past, the nearest observation before the listed time is displayed. If the Forecast tab is selected, the TAF for that station is shown. It should be noted there are fewer TAF stations than available METAR sites.
The stations displayed follow a progressive priority scheme that will show more stations based on the zoom level. This density and size of the text and weather symbols can be adjusted by clicking on the METAR tab under the OBSERVATIONS menu within the Map Options tab.
Flight Category
This displays only the flight conditions at a particular airport as a colored dot. The flight category display uses the same priority filter system as the METAR plots but the density is much higher.
PIREPs
Icing, turbulence, and null PIREPs are available to view. The user can select the age, scale, and minimum intensity for the PIREPs displayed. The default is to show only PIREPs reported in the last 90 minutes and those within +/- 3000 feet of the selected flight level.
SIGMETs
This displays the current valid SIGMETs. This will show both domestic and international SIGMETs. The opacity of the SIGMETs can be adjusted under the WARNINGS & ADVISORIES menu within the Map Options tab. SIGMETs can be distinguished by their red outline and red labels.
AIRMETs
This displays the current valid AIRMETs time centered in a three hour window. The Opacity of the AIRMET can be adjusted under the WARNINGS & ADVISORIES menu within the Map Options tab.
NWS Hazards
NWS hazards are viewed by clicking on "NWS Warnings" under the WARNINGS & ADVISORIES menu within the Map Options tab. The opacity can be adjusted as well.
Wind Barbs
This displays wind barbs based on the flight level selected, or at the surface. The wind barbs are filtered based on zoom level. As the display is zoomed in, more wind barbs will display. Wind gusts are denoted by red.
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