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One will sometimes see a question mark in the body of a TAF (Terminal Aerodrome Forecast), such as in the second line below:

TAF MDLR 162200Z 1700/1800 00000KT 9999 SCT018
  PROB30 1704/1710 8000 ?SHRA BKN016 
  BECMG 1713/1715 07010KT

Is there any time that this is correct, or should it always be considered a typo when it is encountered? I haven't found any references to such an annotation while searching online, but those resources tend to be FAA-centric, and if other weather reporting uses that punctuation to convey a specific meaning, I'd be interested to know about that.

Ralph J
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    I entered the TAF in your question into a TAF decoder program and the result shown for "?SHRA" was "not decoded. " I'm guessing it would be a typo. See: https://e6bx.com/taf-decoder/ –  Dec 16 '22 at 22:58
  • @757toga Good thought on that. The decoder at aviationWeather.gov seems to ignore the question mark & decodes it as if it were just "SHRA" rather than "?SHRA". I'm hoping to see if any jurisdiction besides FAA-land uses that punctuation to coney information -- I'm pretty certain that in the US, it'd just be a typo if it shows up. I realize that I may be asking for somebody to "prove a negative" here, which may be tough. A lack of any "yes" may be all the answer I can hope for. – Ralph J Dec 16 '22 at 23:39
  • In METARs, a question mark indicates that the reading is not reliable. Presumably the equipment is throwing error codes and needs maintenance. Maybe this pertains to TAFs as well? – Skip Miller Dec 17 '22 at 02:01
  • @SkipMiller Sounds reasonable. But do you have a reference that shows that a question mark in a METAR means a reading is not reliable.? –  Dec 17 '22 at 16:19
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    A TAF isn't a reading, but rather a forecast; the lack of a rain/visibility/whatever sensor removes that value from a METAR report, but a forecast should still be able to predict all those thing, I'd expect. – Ralph J Dec 17 '22 at 17:31

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There are no question marks nor any reference to them in neither the ICAO Annex 3 nor the WMO 306 Manual on Codes. These documents are the standards used for meteorological reports and forecasts in aviation. There might be national exceptions to these though.

cars
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    Where might one find national exceptions? Specifically, for the Dominican Republic & the Bahamas -- those seem to be where the question marks (the D.R.) and other nonstandard punctuation (slashes in Bahamian METAR reports) often show up. – Ralph J Dec 17 '22 at 21:00
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    I don't know, but my bests guess is the (national) Aeronautical information publication (AIP). Maybe you could ask the local weather briefing if such is available – cars Dec 17 '22 at 21:05