[Xastir] New nws maps

[Jason Jordan]

Howdy Folks,

      To answer the questions about the products:

>>       http://www.srh.noaa.gov/ridge/RadarImg/N0R/CAE_N0R_0.gif
This is base reflectivity at the 0.5 Degree tilt.  It will be the highest 
resolution radar image available from the NWS.

>>       http://www.srh.noaa.gov/ridge/RadarImg/N0S/CAE_N0S_0.gif

Lance is correct in that this is Storm Relative Motion.  The movement of 
most of the storms is computed by the algorithms in the NEXRAD radar and 
then "removed" from the doppler wind field to give a better estimate of 
what the motion of the winds are within storms.  Great for looking to see 
if storms have rotation.

For all the Velocity products, Green colors are towards the radar (negative 
values) and red colors are away (positive values).

>>       http://www.srh.noaa.gov/ridge/RadarImg/N0V/CAE_N0V_0.gif

This is also the lowest tilt of base velocity, usually around 0.44 to 0.5 
degrees depending on the radar.  Great for tracking wind shifts from fronts 
or sea breeze fronts.


>>       http://www.srh.noaa.gov/ridge/RadarImg/N0Z/CAE_N0V_0.gif

It's hard to tell from the image but this looks like composite 
reflectivity.  This one will show the highest reflectivity on any elevation 
slice the radar takes from 0.5 to 19.5 degrees.  Good to track where the 
strongest part of the storm is, but be careful!  The highest reflectivities 
might not be at the ground, but aloft!

> >       http://www.srh.noaa.gov/ridge/RadarImg/N1P/CAE_N1P_0.gif

This is one hour precip...updated every hour when the radar believes there 
is rain in the area.  It can update if there is ground clutter that has not 
been removed.


> >       http://www.srh.noaa.gov/ridge/RadarImg/NTP/CAE_NTP_0.gif

Storm total precip will get a bit tricky as some of the new builds of the 
software that controls products allows the NWS office controlling the radar 
to set the time the STP will reset.  Most offices leave it at the default 4 
hours however.  There is also a feature now where the  local office can 
reset the storm total precip if the event is ongoing for several days (such 
as the hurricanes over Florida last year).

Be watching for more products from the NWS that can be used in 
Xastir.  There is a push for more "GIS" friendly products.  The radar is 
the first step and all the sites in the US can now be interfaced via the 
web through www.srh.noaa.gov/ridge/ which is done by the Southern Region of 
the NWS.  Individual images reside in the directory structures above and 
can be accessed by changing the 3-letter identifier for the radar (i.e. CAE 
to AMA in all the image names)

-Jason Jordan

P.S.  I'm still having trouble getting internet maps such as terraserver 
and radar images to overlay in XASTIR.  They come up as black images and I 
believe it was discussed earlier on this list.  We're running 1.5.0 on a 
RHEL WS 3 at 16bit color depth.  Unfortunately, we cannot roll-back the 
rpm's for imagemagick due to NWS security requirements.  I uninstalled the 
rpm's and complied the latest version available (and could not roll back to 
an earlier version - again, security issues).  Any ideas?  Our hams (and 
myself included!) miss having the radar overlay when getting our spotters 
into position.  TIA!



-------------------------------------------
Jason Jordan, KC5KND
Webpage: http://members.cox.net/kc5knd/
E-mail:  kc5knd at cox.net

Meteorologist
National Weather Service Amarillo, TX
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