Re: Using NWS County shapefiles for other packets

Lynn Deffenbaugh

Actually, I would recommend looking into using the NWS MultiLine format for this purpose.  It requires nothing to be installed except an APRS client that supports this display.  You can't transmit the same level of detail as a local shapefile selection can deliver, but you also don't need to have shapefiles installed to see the described area.  Another advantage is that the base packet still supports location, symbol, and comment text, unlike the shapefile selection stuff.

This is what KJ4ERJ-15 uses to put the footprint circles around the ISS and PSAT* satellite objects.

As for where the flood symbol comes from, it is the "product code" that is "FLS" for "Flood Statement" in your example packet.  The "source" callsign is the NWS office (or zone) and product code concatenated together.  In ARPSISCE/32, I went through all of the product codes and selected symbols for them for display.

The MultiLine format is generated for weather alerts as well and is what carries the non-shape shapes that are actually drawn by the weather forecasters themselves when alerts are issued.

And yes, this originated in the USA, but the Australians are doing their own thing.  The base pages for this information is (although the Australian page didn't come up when I just tried it):

I'd have to go check the source code to see what the conditions are that trigger the shapefile lookup, but I know the multiline is simply the presense of the proper }xxxxxx{seq# at the end of a packet.  Here's a few samples from the satellite objects:

KJ4ERJ-15>APZTLE,TCPIP*,qAC,NINTH:;ISS      *234348h4637.47N\09311.67WSMsg4Pass }k1mkNbrQzAq5a1N5;A+Q#b*kN{!wJU!
KJ4ERJ-15>APZTLE,TCPIP*,qAC,NINTH:;PSAT     *234355h3709.89N\10424.05ESMsg4Pass }k1kpNhnTz@t1c,N19@(T"h.pN{!w0'!
KJ4ERJ-15>APZTLE,TCPIP*,qAC,NINTH:;PSAT2    *234424h2649.97S\13728.36WSMsg4Pass }k1iuNne\vEz0l'N00E#\&n7uN{!wm<!
And lots more at (but thinks the satellites fly too fast!)

Oh, and the !xxx! as the "sequence" was specifically chosen to make it different than an NWS multiline which will always have a letter or digit as the first character after the {.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

On 4/7/2020 7:13 PM, Fred Hillhouse wrote:



This is cross –posted to APRSSIG but the list appears to have been replaced by a forum. It is also on the Facebook APRS page.


Is there a mechanism to use the shapefiles that encompass counties for anything other than an NWS packet?

Here is an example that will display a FLOOD symbol inside two counties along with county outlines



After studying the details and documents for this packet (Thanks WE7U!), I am curious if other data could be displayed.


Is the packet type generic enough?

Can “NWS_ADVIS” be anything else?

I am not sure what determines the FLOOD symbol. Is it the product code of “FLS” or “FLOOD”?


A current scenario might be COVID-19 cases in a county, but that is only one example.


Just thinking about current world events and APRS.


I know the NWS is US based. Are other shapefiles available for counties, states, provinces, etc.?


I hope everyone is being careful and rides out this storm successfully!


Best regards,

Fred N7FMH


PS. The New York Times maps and data (free subscription for COVID-19)


PPS. Is the APRSSIG email list really replaced by a forum? L


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