For the upcoming thermalling season, I will be experimenting with providing predictions of conditions at Walker Ridge for Williams gliderport users. This email introduces the "xWalkerRidge BLIP" that will be available and tells how you can help improve its predictions. BACKGROUND - the Williams "mountain" TIP Back when the "mountain" Williams TIP was being setup there was talk of trying to predict conditions at Walker Ridge, since that is a common tow/release spot for Williams pilots. However, it was decided to instead try to predict conditions deeper in the mountains and Milt Hare "calibrated" the MTwilliams TIP based on flights into Snow Mt and beyond. Part of the reasoning behind this decision was that the "mountain" TIP would need to use soundings and Tmax at Marysville but these are already used for the "regular" Williams TIP, so "mountain" TIP predictions for Walker would not differ all that much from the regular Williams TIP. However, since that time I have obtained access to fine scale MAPS model output from NOAA's Forecast Systems Laboratory, which predicts soundings and surface temperatures at 20km intervals. This data has been used to produce the BLIPMAPs and I have also been producing individual "BLIP"s which provide numerical values at chosen specific locations during the day (see "http://www.drjack.info/BLIP/index.html"). However, these BLIP results are for _averages_ over the 20km grid square and soaring pilots try to find the _highest_ thermals, which in mountainous terrain often occur at local terrain protuberances having surface elevations well above the "average" terrain, since heating there produces thermals with higher tops than those over the surrounding terrain. I now hope to allow for such local variations by using an empirical adjustment to the model predicted surface temperature to better predict thermal soaring heights at such features, such as Walker Ridge. THE NEW EXPERIMENTAL BLIP: xWalkerRidge I have created the "xWalkerRidge BLIP" at http://www.drjack.info/BLIP/xWalkerRidge.txt which predicts thermalling conditions throughout the day at Walker Ridge. Quite a few numbers are presented there, generally corresponding to BLIPMAP parameters plus wind and humidity profiles, but the important parameter is the "BL Top" which gives an estimate of the maximum thermalling height in elevated terrain (over _flat_ terrain the Hcrit value would be the valid parameter). Predictions for 21Z (1AM) are initially produced around 10PM the night before and values for that and other hours are produced/updated throughout the night and morning. Of course the usual caveats apply, that these predictions are only for thermal soaring, that cloud predictions are weak, etc. These predictions use the MAPS data for a gridpoint location close to Walker Ridge and so use sounding and temperature predictions which should be much more appropriate than use of Marysville predictions. They also use a surface temperature which is artificially increased above that predicted by the MAPS model for that location. This increase is required because of the difference between the smoothed height used by the MAPS model at that location, of 2220 ftMSL, and the actual Walker Ridge elevation of 3587 ftMSL. However, the adjustment presently used is simply a guess based upon some rough estimates. What is needed are observations which can be analyzed to give a better empirical temperature adjustment and thus provide more accurate predictions. HOW YOU CAN HELP - use the BLIPEX page How well do the soaring heights predicted by the xWalkerRidge BLIP agree with those experienced by pilots? No one knows at this point. To help address that question I have created a page which makes it easy to submit your flight reports of the maximum thermalling height at Walker Ridge: http://www.drjack.info/BLIPEX/index.html I hope that those interested in obtaining better predictions at Walker Ridge will use the Javascript form there to send in their observations. (The form is being used to alleviate some of the workload on my end, which is already higher than I would like it to be. Information is also give for those who do not wish to use the Javascript form). Your data will be used, first of all, to create a plot of observed vs predicted altitude, which will appear at the BLIPEX page. But more importantly, they will also be used to change the empirical temperature adjustment to give better agreement with reality. I hope you will keep this message in mind when you are taking tows to Walker. The thermalling season is not really here yet, but I wanted to have something in place when it does arrive. It will take awhile for enough data to be gathered and analyzed, so do not expect to see any immediate change in the empirical temperature adjustment or the BLIP predictions. (Unfortunately data from old flights cannot be used because I had not been archiving the data needed for the analysis.) I do hope that those who utilize the Walker Ridge BLIP will "pay the piper" by submitting their flight reports, putting something back into the process so the predictions can be improved. THE FUTURE ? This method could of course also be used to make forecast for other locations using the MAPS model data. For example, it might be used to provide a better "mountain" prediction than the present MTwilliams TIP since it can use local sounding and temperature predictions instead of having to extrapolate from Marysville soundings and temperatures. However, BLIPs can only predict for the current day while the TIP makes predictions for up to two days in advance. Whether other "empirically adjusted" BLIPs become available will depend upon pilot interest and upon the degree of success of the xWalkerRidge BLIP. I should note that there is no guarantee that the xWalkerRidge BLIP will prove to be sufficiently accurate for soaring usefulness - much depends upon the accuracy of its local surface temperature predictions and the empirical temperature adjustment is an ad hoc treatment. Of particular concern in evaluation forecast usefulness will be the relative sizes of the "signal" and the "noise". But if these forecast do succeed then it will be a significant advance in soaring prediction. Nothing ventured, nothing gained.