Cannot parse where visibility is directional about metar-taf-parser HOT 3 CLOSED

Based on the following, page 25-28, it appears as if the directional visibility will always accompany a primary visibility.

https://www.vaisala.com/sites/default/files/documents/Vaisala%20unmanned%20automatic%20weather%20observations%20at%20airports.pdf

The minimum visibility is also included when the visibility in one direction, which is not the prevailing visibility, is less than 1,500 meters or less than 50% of the prevailing visibility and less than 5000 meters. A direction is also added if possible, as N, NE, E, SE, S, SW, W and NW. If the direction cannot be determined like in AUTO metar, NDV (No directional visibility) keyword can be used.

It seems like a visibility with a direction attached will always have a prevailing visibility (without a specific direction). For example

3200 1200SW

Here's you example, but with the above visibility string, working correctly:

https://aeharding.github.io/metar-taf-parser/metar?input=CYVR+301300Z+09006KT+3200+1200SW+2000NE+FEW055+FEW120+M04%2FM06+A3049+RMK+SC1AC1+SC+TR+SLP327

It seems like it may be possible (?) to have more than one minimum visibility directions, but I'm not sure.

Do you have a specific example of a real METAR with a direction but without a prevailing visibility?

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You may well be right, but it's frustratingly difficult to find a definitive resource.

This reference backs up your theory:

But this source only refers to "two groups" (not in addition to a prevailing group):

And then this source again suggests there is a prevailing visibility followed by a directional visibility:

On balance (and based on the "officialness" of the above sources) it does seem that you're correct that a directional visibility should follow a non-directional visibility.

Happy to close this if you are.

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Sounds good! Please let me know if you find anything weird like this in a real METAR and I will reopen this.

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