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wmo-im / iwxxm

XML schema and Schematron for aviation weather data exchange
https://old.wmo.int/wiswiki/tiki-index.php%3Fpage=TT-AvXML
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Attribute cloudAndVisibilityForecast in MeteorologicalAerodromeForecast in TAF should be optional #233

Closed blchoy closed 3 years ago

blchoy commented 3 years ago

@jkorosi reported that as attribute cloudAndVisibilityOK is not optional, he will have to determine in both the main and change groups of a TAF boolean values for this attribute which is not necessary in some cases. For example:

TAF FAOR 062200Z 0700/0806 18010KT CAVOK TX12/0713Z TN07/0703Z
    BECMG 0700/0702 BKN012
    PROB40 TEMPO 0702/0706 3500 BR BKN008
    PROB30 TEMPO 0703/0705 0800 FG VV002
    BECMG 0703/0705 11012KT
    BECMG 0710/0712 07010KT BKN030
    PROB30 TEMPO 0715/0721 5000 -SHRA
    BECMG 0722/0724 01012KT

Only the main group needs to specify cloudAndVisibilityOK="true".

If we follow TAC strictly cloudAndVisibilityOK should either be true or not mentioned but never be false. Having said that, for the change group "BECMG 0700/0702 BKN012" there is no harm if one also mention cloudAndVisibilityOK="false".

In any case, as suggested by @jkorosi, we will be making this attribute optional in the next update. Note that the description of TAF.TAF-8 should also be changed: "TAF.TAF-8: In a non-empty iwxxm:baseForecast when @cloudAndVisibilityOK is false or empty iwxxm:prevailingVisibility and iwxxm:cloud are mandatory"

blchoy commented 3 years ago

This was implemented in IWXXM 2021-2RC1.