CAP tends to be less than specific about the areas covered, with regard to
the VTEC-generated "weather wire" alerts. There are methods to get those
in, as well. Some of us have been dealing with discrepancies in WEA and CAP
for a long time and in the professional arena.

On Fri, Aug 4, 2017 at 10:11 AM, Dan Srebnick <> wrote:

> I've developed a NWS CAP protocol parser to inject local weather events
> into APRS.  In doing so, I spent much time researching the required
> format of such a message.
> I found detailed comments in alert.c.  I also found a document from
> WB4APR ( that was updated in 2010.
>  There is documentation on that shows how
> they format their Weather Alert packets and may represent the current
> best practice.
> The three sources of info don't completely align.
> Comments in alert.c indicate that the "title" in received packets
> should include an underscore between the state and the zone, i.e.
> NJ_Z014.
> Packets generated via WE7U and AE5PL omit the underscore.  That is what
> Xastir actually seems to require, as it adds the underscore itself.  If
> the underscore is included, Xastir adds a 2nd and the display in the Wx
> Alert window does not work properly.
> I am also trying to clarify whether the underscores between multiple
> words in the "alert_tag" are required.  Xastir comments state, "You
> must ignore anything after a space in the alert." WB4APR says the
> "type" is free text.  Xastir doesn't actually seem to care and my
> generated alerts look nicer without the underscores.  But WE7U does use
> it.
> Thought: Perhaps WE7U's data source includes underscores where the CAP
> atom feed does not.   I see that WE7U is one of the primary developers,
> so please chime in.
> Nor does Xastir seem to care if there is a trailing comma (as specified
> by WB4APR) after the last "title" element or a space between the last
> "title" and the "{zcs" value.
> Perhaps the comments are out of sync with the current reality and could
> be clarified by someone who fully understands the code as implemented?
> This could be quite useful.
> The NWS CAP protocol (
> curr.pdf) has defined the following "Significance" values:
> W - Warning
> A - Watch
> Y - Advisory
> S - Statement
> F - Forecast
> O - Outlook
> N - Synopsis
> Xastir already handles Warning, Watch, and Advisory.  I would find it
> useful, and therefore suggest/request, that the
> values be expanded to conform with the NWS CAP possibilities and to add
> STMNT, 4CAST, OUTLK, and SYNOP to the list of values.
> Thanks for any comments and your consideration.
> 73,
> Dan K2DLS
> _______________________________________________
> Xastir-dev mailing list

Gerry Creager
“Big whorls have little whorls,
That feed on their velocity;
And little whorls have lesser whorls,
And so on to viscosity.”
Lewis Fry Richardson (1881-1953)
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