Hi Robert, I'll be very interested to see your comparison of XCSkies and RASP. The XCSkies interface looks excellent, especially the use of Google maps. The NSW RASP does provide 2 day forecasts, but not three day (it could, but I question the accuracy of a 3 day forecast). I'd be interested to know what resolution they claim. Meanwhile, here's some comments posted by Davis Straub (professional hang glider pilot):
http://ozreport.com/1209561982 XC Skies - I used it at the Santa Cruz Flats Race When I was in Australia I had the option of using RASPs that were built for each state by sailplane pilots to forecast the soaring conditions or XC Skies. Both use the US NOAA modeled weather values from the GFS database. This data allows one to predict the soaring conditions for any where on earth (well, I don't know about the polar regions). The Columbian pilots tell me that they use XC Skies, as it is the only thing available to them in their area (and this is true for most of the world). I used the RASP models in Australia for a number of reasons. They provided hourly values and this turned out to be very important (and very accurate) when predicting the surface winds at the launch time in Forbes. The RASP models would allow me to download many graphics for a given day, say all the lift graphics from 8 AM to 7 PM, all the top of the lift graphics, wind (surface, average, top of the lift) graphics, etc. for each hour. I could then very quickly go through each graphic and see what the pattern was for the day. Human beings are great at pattern recognition. The RASPs were very quick and easy to work with. The only problem I had was that I could not zoom in and look at a specific area, say around Canungra or Beechmont. And I didn't have a background map behind the weather data (using the weather data as an overlay) that allowed me to pinpoint exactly where the forecast was for. In Arizona, I didn't have a RASP forecast for the area around Casa Grande. A RASP can be specified for any given area by the person hosting the RASP (using programs developed by Dr. Jack), and there wasn't one for Arizona. I did have access to Dr. Jack's original BLIPMAPS (which I subscribe to), but they encompass a four state area. A bit too big for what I really wanted to see. So I turned to XCSoar and zoomed down to the area that we would be flying in around Casa Grande. And given the fact that I could use the RUC or the ETA model with XC Skies (not just GFS), just like BLIPMAPS, meant I could compare the output from the two models to see if things made sense (or at least were consistent). XC Skies only produces output for every three hours (which given its world wide coverage is very understandable), but that's true of BLIPMAPS also. I was spoiled by the special RASPs that have been setup by sailplane pilots in Australia. But soaring forecasts for every three hours are adequate. XC Skies does not let me store the graphic images (it uses a whole different way of displaying data allowing one to pan and zoom over Google Maps), so it was slow each time I shifted between hours or between lift values and height of lift or wind values. That was disappointing as I had a relatively slow (3G) internet connection. Also XC Skies doesn't seem to remember me when I first start it up and I have to go back and log in. Maybe I'm doing something wrong, perhaps going to the wrong page at first. BLIPMAPS remembers that I have a subscription not matter which page I start up with (it's got its cookies straight). I can't get XC Skies to start with RUC data, it always starts with GFS and I can't get it to remember my UTC offset. Thankfully when I was in Arizona I could use the default at -7. In Australia it was +10 or +11. In XC Skies, you can set up a number of "profiles" which represent different geographic areas where you want to see the forecast. The profiles don't remember the database you want to use or the UTC offset (or maybe I can't figure out how to get them to). They do remember your zoom level though and the "transparency" value that you put on your weather overlay (over the Google Map). I use a transparency value of 6. XC Skies makes it easy to bring up the interactive version of the Tskew chart for any given location, so you can see the projected wind speeds and direction through the lift column, as well as the forecasted temperature at top of the lift. BLIPMAPs provide a useful MINI-BLIPSPOT for any point. I can't say that the forecasts from BLIPMAPS or XC Skies for the Casa Grande area were all that good (at least while we were there) for lift and top of the lift, although they were darn good on winds. In fact, those were the worst forecasts from these tools that I've seen so far. I remember how right on the RASP forecasts were in Australia. I didn't try using the GFS or some other modeled weather parameter dataset, just RUC. The lift was usually lighter and the top of the lift lower than the forecasted values. Often hang glider pilots can get to the top of the lift and we were often two or three thousand feet below the predicted values, except on one day. Also the lift was weaker than forecasted by a couple of hundred feet per minute or more. _______________________________________________ Aus-soaring mailing list [email protected] To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
