The Weather

Some flying destinations advertise with comments such as ¨flyable over 300 days per year¨. When people ask me to quantify flyable days per year in Piedrahita I can confidently say 365 days per year. It is always flyable everywhere! However, you may not enjoy the experience or necessarily survive it.

There are days when it is just not worth trying due to wind strength or storm activity. There are plenty of other things to do here. So we do them, rather than wasting the day in the forlorn hopes of a flight. Many of our alternative activities can be fitted in during a non flyable part of the day, and we prefer to do that rather than wasting the whole day driving or waiting.

Weather Forecasts

The are a large number of sources of weather information, these are a few that we regularly make use to get a general overview.

The 'Forecast Tree'

There is a growing tendency for pilots to depend on the new forecasting devices and fail to just go outside and look at the sky. My principal forecasting device is still a tall poplar tree which I can see through the kitchen window.

If there is no movement in the tree at breakfast time and the sky is clear we are pretty much assured a good flying day. If there is some movement or any form of cloud, then we may have to work a little harder for our flying that day. Maybe travelling a little further or perhaps having to wait. However, if it is flyable within safe margins, we have the local knowledge to be at the right site at the right time.

Local Weather Station Data

Most useful to us on a daily basis are the actual observations taken hourly at various points around the province.

http://www.inm.es/web/infmet/tobsr/emas.html

You will first have to click on any dot in Castilla y Leon [1].

This zooms you into the provinces in the Piedrahita area [2].

We are most intested in the dots in Avila , and a few dots in Salamanca (the Hoya / Covatilla) and Segovia. The village of Navaredonda de Gredos is on the plateau behind Peña Negra, which gives us a good reading of winds at take off height.

La Covatilla, some 35km to our West is also high up on the ski resort, and will show early on if we are going to get a strong westerly coming in later. A reading in Avila will normally show south before 10am, but will normally change to NE or NW later on. There can be strong winds showing at La Covatilla and Avila early in the morning, but this does not necessarily mean it will not be flyable as they may be due to some local meterological effects. However, strong winds at Navaredonda early in the morning means that we will be considering another activity till late afternoon.

The wind strengths and directions also give us an important idea of possible convergence areas and how the day is developing.

More detailed Forecasts

It is useful to have estimates of the wind speed and directions at different heights, estimates of the height of cloudbase and the possibilty of an inversions. All this information can be obtained from the NOAA Air Resources Laboratory site.

This information comes from a model with a large grid, with no information on small scale local terrain, it is only really useful during the afternoon period when local effects are less significant.

This site provides predicitons for every meteorological parameter you can think of. We will just concentrate on the sounding here.

More information on soundings will be included soon.

The future

Many computer mapped weather projections work on a wide area grid and do not take into account of local topography. Local wind direction will often be different to the predicted geostrophic wind due to the effects of the terrain. The grid scale of the web site, www.meteosimtruewind.com with its MASS modelling has a grid area of only 5km and taking into account terrain. It currently covers with this small grid scale only the northeast of Spain (Catalonia). There you can now forecast a range effects such as sea breezes, large scale catabatic winds, valley winds and convergences. Hopefully a higher resolution of the rest of Spain will in future become available.