On the day

These are the key sites which I may check out the evening before and/or early in the morning when I hope to fly from Fiesch, firstly to make the final decision as to whether to go at all, and secondly to get an idea of what conditions to expect, not only there but also in other places which could be relevant to XC flight planning.

I take a glance at the synoptic chart first, to be able to put everything else in context.

Then I go to the Swiss TV/radio forecast; although I have enough German to be able to understand this, if you don’t then there’s always a Google Translate version!  Although the information may not be very technical, it is usually pretty accurate, and often covers key points such as the chance and timing of showers and storms later in the day, or of high cloud moving in, which can be very helpful to anticipate.  Also, if valley winds are expected to be stronger than usual, this is nearly always mentioned here.

Daily and longer-term forecasts (in German), aimed at sailplane pilots, are often published by Flugplatz Schänis, located in Eastern Switzerland – close enough to be relevant to Fiesch.

The Meteoblue page for Eggishorn sets out a very basic diagram of how the weather there is expected to evolve over the course of the day (although the wind predictions are rarely accurate).

Profiwetter and Windundwetter charts show current and forecast differences in atmospheric pressure across the Swiss Alps.  The importance of this parameter is explained on the föhn and bise pages.  When the pressure differences are excessive, it’s unlikely to be safe to fly around Fiesch, so there may then be little point in looking at more specific information.

I next look at predictions of wind speed and direction at various altitudes over the course of the day at XTherm (which seems to take more account of topography than any other free website) or (if that’s unavailable) Meteoblue, where a good range of different levels is displayed.  I consider the figures for 3000m ASL and 800m AGL to have the most important influence on overall flying conditions, e.g. large-scale headwinds/tailwinds and turbulence, followed by 2000m ASL for the strength of valley flows.

If I’m concerned that the flying day could be curtailed by precipitation or cloud, my favourite site to show when and where these may be expected is Search.ch.  To distinguish high cirrus from spreadout,  XCTherm has charts of high, medium and low cloud (but I don’t find their greyscale display very easy to interpret).

If you like emagrammes, charts of soundings from Payerne, located only 100km to the north-west of Fiesch, are provided by MeteoSwiss.  However, measurements of the free atmosphere in the flatlands from several hours previously often bear little resemblance to conditions in the mountains.  You can ignore the wind numbers, and the local humidity and temperature profile may be completely unrepresentative; e.g. after a local downpour the night before (not unusual in the flying season), it may take until midday for the consequent moisture to evaporate and base to rise above takeoff, even in August.

Maps displaying wind readings from locations all over Switzerland at various altitudes are worth checking out in the morning to see how well what’s actually happening corresponds to the forecasts.  Sometimes, unflyably strong winds predicted for 3,000m simply don’t materialise.  Winds appears to show the greatest number of stations, with SpotAir not far behind.  I don’t pay much attention to individual stations in isolation as these may well be influenced by temporary local effects, e.g. Eggishorn nearly always shows a vigorous westerly early in the morning.  However, if there are brisk northerlies not only there but also at the Sidelhorn, Grimsel Pass and over the peaks in general, then the day may well be a write-off.

It may be useful to check out the local webcams, e.g. if there is cloud around which is expected to clear.  The Fiescheralp panorama is at the level of the Heimat launch area, and includes a couple of flags to indicate if the wind strength and direction is ok.  The Eggishorn panorama gives a better view of the general weather, including approaching high cirrus, and if you have a large screen and sharp eyes, you may also be able to pick out airborne gliders.

Finally – although this is obviously not a weather site – I check the Daily Airspace Bulletin for Switzerland for the status of the Sion TMA and any other relevant information, e.g. temporary restrictions which can sometimes be imposed.

A case study provides a real-life example setting out the way that I put this scheme into practice in the planning of a flight on 26th June 2017, followed by an account of how things actually turned out.