Aviation Digital Data Service (ADDS)

Output produced by TAFs form (0310 UTC 25 May 2017)
found at http://www.aviationweather.gov/adds/tafs/
 
Forecast for: EGLL (LONDON/HEATHROW , GB)
Text: TAF EGLL 242253Z 2500/2606 19004KT CAVOK
Forecast period: 0000 to 1300 UTC 25 May 2017
Forecast type: FROM: standard forecast or significant change
Winds: from the S (190 degrees) at 5 MPH (4 knots; 2.1 m/s)
Visibility: 6 or more miles (10+ km)
Clouds: not forecast
Weather: NSW  (no significant weather)
Text: PROB40
Forecast period: 0300 to 0800 UTC 25 May 2017
Forecast type: TEMPORARY: The following changes expected for less than half the time period
Visibility: 5 miles (8 km)
Weather: no significant weather forecast for this period
Text: TEMPO 2503/2508 8000
Forecast period: 1300 UTC 25 May 2017 to 0600 UTC 26 May 2017
Forecast type: BECOMING: Conditions expected to become as follows by 1600 UTC 25 May 2017
Winds: from the E (100 degrees) at 12 MPH (10 knots; 5.2 m/s)
Visibility: 6 or more miles (10+ km)
Weather: NSW  (no significant weather)