Weather: Difference between revisions

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Weather (view source)

Revision as of 12:48, 2 June 2014

5,732 bytes removed ,  2 June 2014
moving METAR/TAF info to Weather reports, removing TAF example because it was copied from wikipedia (!)
m (→‎Explanation: Wikitable)
(moving METAR/TAF info to Weather reports, removing TAF example because it was copied from wikipedia (!))
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or use the Weather Scenario dialog from the menu at '''Environment->Weather Scenario''', where you can select a predefined weather, enter your own METAR or even enable live weather data. This options enables a task, that calculates your nearest airport and fetches the current METAR for that station from NOAA weather service.  
or use the Weather Scenario dialog from the menu at '''Environment->Weather Scenario''', where you can select a predefined weather, enter your own METAR or even enable live weather data. This options enables a task, that calculates your nearest airport and fetches the current METAR for that station from NOAA weather service.  
An internal interpolation routine applies weather changes smoothly when changing the METAR.
An internal interpolation routine applies weather changes smoothly when changing the METAR.
== METAR ==
A METAR is a codified observation message indicating an airfield weather conditions observed at a given time. There are different ways of messaging weather reports, but in [[FlightGear]] METAR is used. The data is retrieved from [http://weather.noaa.gov/weather/metar.shtml NOAA].
The METAR-message can be found acros the menu (Weather > Weather Scenario). To have the actual weather (or playing with [[ATC]]) you need to enable the Real weather fetch in the [[FlightGear Wizard]].
Such a message is established every hour.
=== Explanation ===
'''Example:'''
{| class="wikitable"
|2008/03/15 12:24 || KSFO || 151224Z || 05012KT || 10SM || SN || BKN050 || 02/M08 || A3016 || RMK AO2 SLP228 || T00221083
|-
|1                || 2    || 3      || 4      || 5    || 6  || 7      || 8      || 9    || 10            || 11
|}
# Date
# [[ICAO-code|ICAO]] Identifier (4-letter)
# Issuance Time DDHHMMz (UTC)
#* COR (CCD in Canada) if correction to observation
# Wind
#* First 3 digits: True Wind direction or average if variable (VRB).
#** Note: If the wind direction varies 60° or more, the direction will be indicated with a V (e.g. 180V250)
#* Next 2 digits: Mean speed and units
#** KT=knots, KMH=kilometers/hour, MPS=meters/second
#* G (gust) as needed – 2 or 3 digit maximum speed
#* Calm will be indicated by 00000KT
#* Example: 18012G22KT 150V240
# Horizontal Visibility
#* Prevailing Visibility (PV)
#** Statue miles (SM) and fractions (US & Canada only) or,
#** 4 digit minimum visibility in meters, and,
#** Lowest value and direction, as required (shown as a remark)
#* Runway Visual Range (RVR)
#** R: Runway Designator, L/R/C as needed, “/”
#** P/M: Plus/Minus (US only)
#** 4 digit value (feet/meters)
#** V (variability) with tendency U/D/N (up/down/no change)
#** Example: R18R/1200FTV/U
# Present Weather (Constructed sequentially):
#* Intensity
#* Descriptor
#* Precipitation (Dominant type is listed first if more than one type reported)
#* Obscuration
#* Other
# Sky Cover
#* Cloud Description
#** Amount in eights (octas)
#** SKC=Sky Clear (clear below 12,000 for ASOS/AWOS)
#** NSC=No significant clouds
#** FEW=Few (1/8 to 2/8 sky cover)
#** SCT=Scattered (3/8 to 4/8 sky cover)
#** BKN=Broken (5/8 to 7/8 sky cover)
#** OVC=Overcast (8/8 sky cover)
# Temperature/Dewpoint (whole °C) (preceded by M=minus)
#* First 2 digits = temperature
#* Second 2 digits = dewpoint
# Altimeter setting (QNH) and indicator (A=InHg, Q=hPa)
# Supplementary Information
#* RE = Recent weather followed by weather codes
#* WS = Windshear, followed by:
#** TKOF/LDG (takeoff/landing)
#** RWY (2 digits runway identifier and designator L/R/C)
#* RMK = Remark
#** SLP = Sea Level Pressure
#** T00221083 (Expanded temp/dewpoint)
#** 1st, 5th digits: 0=plus, 1=minus
#** 2nd-4th digits: temp (decimal missing) (02.2)
#** 6th-8th digits: dewpoint (decimal missing) (-8.3)
# Trend Forecast (2 hours from time of observation) (Not used in US)
#* PROB and 2 digits (30 or 40) = probability 30% or 40%
#* Used to indicate the probability of occurance of alternate element(s) or temporary fluctuations
#* Change Indicator
#** BECMG = Becoming (used where changes are expected to reach or pass through specified values
#** TEMPO = Temporary (fluctuations of less than one hour duration
#** NOSIG = No significant change
#* Forecast Wind (same as item 4)
#* Forecast Visibility (as item 5) (9999 indicates 10Kilometers vis or greater)
#* Forecast Weather (as item 6)
#* Forecast Cloud (as item 7)
== TAF ==
In meteorology and aviation, TAF is a format for reporting weather forecast information, particularly as it relates to aviation. "TAF" is an acronym of Terminal Aerodrome Forecast or, in some countries, Terminal Area Forecast. Generally, TAF's can apply to a 9- or 12-hour forecast; some TAFs cover an 18- or 24-hour period; and as of November 5,2008, TAFs for some major airports cover 30 hours periods. The date/time group reflects the new 30 hour period in Coordinated Universal Time (UTC), as always.
=== Explanation ===
This TAF example of a 30-hour TAF, released on November 5 2008 at 1730 UTC:
<pre>TAF KXYZ 051730Z 0518/0624 31008KT
    3SM -SHRA BKN020
    FM052300 30006KT 5SM -SHRA OVC030
    PROB30 0604/0606 VRB20G35KT 1SM
    TSRA BKN015CB
    FM 060600 250010KT 4SM -SHRA OVC050
    TEMPO 0608/0611 2SM -SHRA OVC030= 
    RMK NXT FCST BY 00Z=</pre>
The first line contains identification and validity times.
* '''TAF''' indicates that the following is a terminal area forecast.
* '''KXYZ''' indicates the airport to which the forecast applies (ICAO airport code).
* '''051730Z''' indicates that the report was issued at 1730 UTC on the 5th of the month.
* '''0518/0624''' indicates that the report is valid from 1800 UTC on the 5th until 2400 UTC on the following day.
The remainder of the first line and the second line contain the initial forecast conditions. Variations of the codes used for various weather conditions are many.
* '''31008KT''' indicates that the wind will be from 310 degrees at 8 knots.
* '''3SM -SHRA BKN020''' indicates that visibility will be 3SM (statute miles) in light (-) showers (SH) of rain (RA), with a broken ceiling (at least 5/8 of the sky covered) at 2,000 feet.
Each line beginning with '''FM''' starts a new forecast period.
* '''FM052300''' indicates the next period lasts from (FM) 2300 UTC on the 5th to 0000 UTC on the 6th.
The remainder of the line has similar formatting to the other forecast lines.
The final line is for errata, comments, and remarks.
* '''RMK NXT FCST BY 00Z''' indicates a remark that the next forecast will be issued by 0000 UTC.
=== External Links ===
* [http://aviationweather.gov/static/help/taf-decode.php Decoding a TAF]


== Related content ==
== Related content ==
* [[Howto: Fetch live aloft data]]
* [[Howto: Fetch live aloft data]]
* [[Weather reports]]


[[Category:Weather| ]]
[[Category:Weather| ]]
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