ADDS TAF Help

Static TAF Plots

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.

Station Model Format

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:

station plot description
Figure 1: Surface Station Data Format
  • Windbarb - The wind barb. The stick points in the direction the winds are coming from. Each full barb represents 10 knots of wind. Each half barb represents 5 knots. In this case, you have winds from the NNW at 15 knots. If there are wind gusts, the number will be displayed at the end of the barb as G23 or gusts to 23 knots.
  • Id - The last 3 letters of the ICAO identifier for the site. LWV is Lawrenceville IL.
  • Vis - The visibility plotted to the left of the weather symbol, in statute miles.
  • Wx - A symbol representing present weather plotted just to the left of the cloud cover symbol.
  • Cover - The cloud cover symbol is plotted in the center. The amount the circle is filled represents the amount of cloud cover. In this case, it's overcast. The color of the circle represents the flight conditions:
    • green - VFR (Visual Flight Rules)
    • blue - MVFR (Marginal Visual Flight Rules)
    • red - IFR (Instrument Flight Rules)
    • purple - LIFR (Low Instrument Flight Rules)

Wind barbs

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.

wind barb graphic
Figure 2: Wind Barb Sample

Flight category definitions

Category Color Ceiling   Visibility
LIFR 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
NOTES:
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.

Cloud coverage symbols

Sky symbols
Figure 3: Cloud Clover Symbols

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.


Present Weather symbols

100 weather symbols
Figure 4: Present Weather Symbols

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).

URL Options

Here is a list of the URL options:

  • region=region - This selects the specific region to display. The regions are:
    • ina - CONUS US
    • alb - Albany NY
    • bwi - Baltimore MD
    • clt - Charlotte NC
    • tpa - Tampa FL
    • dtw - Detroit MI
    • evv - Evansville IN
    • mgm - Montgomery AL
    • msp - Minneapolis MN
    • lit - Little Rock AR
    • pir - Pierre SD
    • ict - Wichita KS
    • aus - Austin TX
    • cod - Cody WY
    • den - Denver CO
    • abq - Albuquerque NM
    • lws - Lewiston ID
    • wmc - Winnemuca NV
    • las - Las Vegas NV
    • pak - Alaska
  • type={prevail|tempo} - This selects the type of plot, either for prevailing or temporary conditions. The default is prevail.
  • valid=yyyymmddhh - This selects a specific date and time to display. ADDS creates a TAF images for each hour out to 24 hours. The default is current.

Example: /taf/plot?region=bwi&valid=2014082905



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