These are a set of static plots generated by ADDS showing a composite station model plot (see Station Format below) for a set of stations in a particular region. There are 19 regions plus a CONUS view. The plot can either display prevailing or temporary conditions. Each plot is updated every 5 minutes. The web page will refresh every 15 minutes.
The station model plot is a standardized way of showing muliple pieces of data at a partcular site. Some of the data are coded and others are shown as symbols. Fig. 1 shows the layout of data. The parameters are:
The wind barbs types are shown in Fig. 2. Calm winds are shown as a concentric around the station location. Long barbs are 10 knots. Short barbs are 5 knots. A flag represents 50 knots. Five knots is a short barb offset from the end. The barb always points in the direction the winds are coming from.
Low Instrument Flight Rules
||Magenta||below 500 feet AGL||and-or||less than 1 mile|
|IFR Instrument Flight Rules||Red||500 to below 1,000 feet AGL||and/or||1 mile to less than 3 miles|
|MVFR Marginal Visual Flight Rules||Blue||1,000 to 3,000 feet AGL||and/or||3 to 5 miles|
|VFR Visual Flight Rules||Green||greater than 3,000 feet AGL||and||greater than 5 miles|
By definition, IFR is ceiling less than 1,000 feet AGL and/or visibility less than 3 miles while LIFR is a sub-category of IFR.
By definition, VFR is ceiling greater than or equal to 3,000 feet AGL and visibility greater than or equal to 5 miles while MVFR is a sub-category of VFR.
Automated stations report "CLR" when clouds may exist above 12,000 feet so a square is used to represent this uncertainty whereas an unfilled circle is used for "SKC" which a human reports the sky is completely clear overhead. The abbreviation "OVX" is unofficial but ADDS uses it here to indicate the sky is obscured which is the case when a METAR reports vertical visibility and no cloud information.
Plots of station data may include one of the following symbols to represent the present weather. METARs may include more than one type of weather condition but only one icon ever gets plotted. Two additional documents show the original descriptions abridged from the World Meteorological Organization (WMO) and which symbol is plotted for each present weather text string. These are not necessarily official but they represent our best matching of weather conditions to the original WMO table of icons.
Original WMO table and abridged descriptions of symbols:
wxSymbols_anno1.pdf (291 KB).
Text string for present weather found in METARs mapped to icons and plotting priority order: wxSymbols_anno2.pdf (313 KB).
Here is a list of the URL options: