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Dale Huguley, KG5QD, has developed a server application which translates the
NWS feed into a useable message format for APRS. Dale's application also
generates APRS objects for tropical depressions, tropical storms, hurricanes,
tornados, severe thunderstorms, and special marine warnings. Extended
information can be obtained by sending a finger inquiry to wxsvr.net. The
link to the left explains more about the finger capabilities of WxSvr as well as
providing a web interface to the finger function.
The databases to the left provide a way to interpret the NWS statements
Dale's application creates and disseminates to the Internet. APRS+SA and
WinAPRS support use of the NWS shape files to graphically depict the watches and
warnings. You can download the files using the "NWS Shape Files" link to
the left.
The current NWS shapefiles are (AWIPS Counties)
c_11mr07.zip,
(Zone Forecast Areas)
z_01ap08.zip, and
(Coastal Marine Zones)
mz08jl08.zip.
If you are interested in programming with .NET to read shape files, I have updated
the .NET MapTools shapelib wrapper found at
http://shapelib.maptools.org to be fully compatible with .NET 2.0. The
MapTools archive found on this web site at
http://www.aprs-is.net/downloads/DotNetshapelibupdate.zip has been tested
with VisualStudio 2008 and is compatible with all .NET 2.0 programming
languages. It does not run as unsafe so it should be usable with any .NET
application. The archive includes all source and solution files. I
have not tested or debugged any of the example and test applications. All
applications should only be compiled in x86 mode to maintain compatiblity with
the shapelib.dll While this is compiled in x86 (32-bit) mode, it is usable
on 64-bit platforms as long as the application is also compiled in x86 mode.
The format
for the NWS statements generated by Dale's server is:
Area Specific:
CWAPID>APRS::NWS-TTTTT:DDHHMMz,ADVISETYPE,zcs{seq#
CWAPID>APRS::NWS_TTTTT:DDHHMMz,ADVISETYPE,compressed zcs{seq#
General/Full Text Messages:
CWAPID>APRS::SKYCWA :DDHHMMz,ADVISETYPE,zcs{seq#
Objects:
CWAPID>APRS:;CWAttttz *DDHHMMzLATLONICONADVISETYPE{seq#
CWAPID>APRS:;CWAttttz *DDHHMMzLATLONICONADVISETYPE}multiline{seq#
CWA
is the NWS office (See databases to the left). The CWA "SEC" is the source
for solar reports and is not listed in the databases as it is a nationwide CWA.
PID
is the product Code (See database to the left).
TTTTT
is ADVIS, WARN, WATCH, etc.
ttttz
is the issue time.
DDHHMMz
is the expiration time.
LATLONICON
is the latitude, longitude, and symbol for the object (standard object format).
ADVISETYPE
is things like FLOOD, FLASHFLOOD, SVRTSM, SEVERE_WEATHER, etc.
zcs
are comma separated zone codes or county codes (see the databases linked to the left
to find the zone or county code for your area), or statement text.
compressed zcs
is a compressed listing of zones or counties (see example below) (note
underscore in To address instead of hyphen).
multiline
is the enclosing line structure for the object (see
http://www.wxsvr.net/APRS_Multiline_Protocol.html).
{seq#
is decoded as:
The first three characters are the "issue time" compressed by
assigning 0-9 as themselves, A-Z as 10 thru 35, a-x as 36-59, where it is DHM
(Day of the Month-Hour in 24 hour format and Minute). Up to 16 this reads as
hexadecimal so {A8B** was issued on the 10th at 08:11 Z.
The next two characters are line numbers which (along with the "From
Call") make the packet unique. Any packet with the "from
Call" and the first 4 digits of the sequence matching are
"associated" packets- in otherwords they are from the same product
or portion of product that is defined by UGC codes.
The final character is for sorting and for assigning some priority to the
various outputs (objects, headlines, packets that highlight counties,
background info).
Compressed Zones and Counties Examples:
COZ91-92-KSZ27>29-41-42
Colorado zones 91 and 92, Kansas zones 27, 28, 29, 41, and 42
TXC67-183-203-315-459-LAC17
Texas counties 67, 183, 203, 315, and 459, Louisiana county 17
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