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Soaring Weather

The purpose of the Soaring Weather Task Force is to introduce and promote broader awareness of some of the newer weather resources which have recently become available to the US Soaring Community. Some of these are relatively simple tools designed to allow us quickly to predict whether there will be soaring conditions for a given day. Others are intended for those whose interest and curiosity push them to understand the concepts and tools available and to begin to prepare their own custom forecasts.

We have gathered together a collection of links, tutorials, and references to texts which we hope you will find useful and informative. To find these click on the links in the top right sidebar.

Especially recommended are the tutorials provided by Richard Kellerman which were presented at the 2003 SSA Convention. If you follow these tutorials through, you should begin to understand how much the tools of weather forecasting have changed in the past few years. Much of this change is due to the timely availability of the numerical model data, especially the MAPS/RUC model. We are also newly empowered by the very fresh infrared and visible satellite data, and the new Doppler radar data (NEXRAD data is as fresh as 5 minutes old). Winds aloft forecasts are somewhat more reliable and available than in the past. The new models are beginning to allow us to recognize and predict some of the mysterious Western convergences (often referred to as shear lines; (see discussion in Dr. Jack's BLIPMAP webpage).

It is our conviction, based on several years of contest weather forecasting (where the audience is always demanding and sometimes informed), that the use of traditional AM balloon sounding coupled with surface temperature estimates is much inferior to the use of PM soundings computed by numerical models. These soundings, particularly those produced by the RUC (Rapid Update Cycle) model, are available on a 20 KM grid (soon to be 13KM) covering any US Soaring site, are updated every three hours, and most importantly, are insensitive to surface temperature errors. There remains controversy about the validity of the model sounding as compared to the older RAOB, and time-honored local early morning soundings taken at contest sites for the past 50 years. But for most of us, the RAOB sounding is from a fairly remote site and we have been guessing that the local air would be similar to the sounding, and often interpolating for expected changes. Similarly, we have been assuming early morning air sampled would be representative of the air we would fly in that PM (or, again, interpolating any change expected). In reality, we have been attempting to do what the models now do for us, that is, estimate what airmass we will have in our flying area during the soaring period. Some concern is also expressed about the lack of recent actual sounding data in the model sounding. It is certainly true of the RAOB sounding (RAOB soundings are available twice a day at Approximately 9AM and 9PM EDT. Those are integrated into the RUC model shortly thereafter), but the MAPS/RUC model also receives numerous other data points that include hourly Metar data for winds, temp, dew point, wind-profiler data, GOES satellite data that include cloud movement, temp and dew-point information as well as Airline descent profiler soundings.

There is much to be learned yet, but the quality of convective boundary layer soaring forecasting has certainly improved. I hope you find the following resources useful. Please let us know if you have useful additions, or if you need help with the links. To contact the Soaring Weather Task Force click here.

Posted: 4/30/2007


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