\u201cI\u2019ve heard that Fiesch is generally turbulent\/windy\/dangerous; is that right?\u201d is the sort of question that I am asked most frequently by pilots who have never flown here. My answer is that hazardous conditions do not arise without a reason, which can nearly always be predicted in advance, enabling you to avoid trouble. However, as larger mountains are generally more sensitive to factors causing turbulence and wind than smaller ones, the occasional challenge to glider handling skills is an inevitable consequence of the topography which produces such exceptional flying here. Also, it\u2019s common to encounter valley breezes around 30km\/hr when landing out in mid-afternoon.<\/p>\n
As far as generalised roughness is concerned, the time of year is an important consideration. In the spring, the combination of a steep lapse rate and intense solar heating can produce strong, sharp-edged thermals, as it can anywhere, but this feature subsides over the course of the season. At any time of year, winds of even moderate strength at altitude and\/or significant pressure differences across the Alps (see overpressure<\/a>) can cause conditions which may be dangerous as well as unpleasant. Finally, it may occasionally be uncomfortably choppy due to an inversion, which is less easy to predict.<\/p>\n Localised winds and turbulence are to be expected in some locations.\u00a0 The breeze in the main Rh\u00f4ne valley west of Brig usually becomes quite strong in the afternoon, often exceeding paraglider trim speed at ground level, so the further you go in that direction, the more likely you are to encounter challenging aerology, especially if you cannot stay airborne or at least keep well away from terrain.\u00a0 If you\u2019re bold enough to take on the challenge of one of the side valleys to the south around here for an FAI triangle<\/a>, you will almost certainly have an upwind battle in one direction of this leg of your flight.\u00a0 Mixing winds in the Grimsel\/Furka Pass area and around Andermatt can also produce sudden disturbances in previously benign conditions, so I prefer to stay high in these regions, particularly when there is any significant airflow or pressure difference in the north-south axis.<\/p>\n Approaching weather\u00a0fronts\u00a0are particularly risky, in that\u00a0they\u00a0may cause days which start with pleasant flying conditions to turn nasty\u00a0quite suddenly.\u00a0 In flatlands, it may be relatively easy to see weather disturbances in the distance,\u00a0with the\u00a0associated changes of wind strength and direction developing gradually enough for pilots to have time to land before conditions become unmanageable. In these large mountains, views may be blocked, and funnelling effects can cause\u00a0wind speeds to change much more dramatically.\u00a0 In particular,\u00a0approaching cold fronts can cause\u00a0f\u00f6hn<\/a> to break through abruptly from any of the side valleys which lead in to the main valley from the south, e.g. down the Agenetal into the upper Goms, the Binntal near Fiesch, the Simplonpass at Brig, the Gotthardpass into Andermatt, and the Val Medel at Disentis.<\/p>\n For further explanation of factors relevant to unpleasant conditions here, the Weather<\/a> page addresses some of the basic principles, and the pages under the Winds<\/a> heading explain more specific details.\u00a0 Meteo sites with the parameters\u00a0enabling you to assess\u00a0the actual risk on a particular day\u00a0are set out in the Looking ahead<\/a> and On the day<\/a> pages in the Links section.\u00a0 In a nutshell: if you’re keen to avoid nasty conditions, don’t fly on days when the forecast shows a significant overpressure<\/a>, winds of more than light strength, or approaching weather fronts, and stay high to the west of Brig and near Andermatt!<\/p>\n","protected":false},"excerpt":{"rendered":" \u201cI\u2019ve heard that Fiesch is generally turbulent\/windy\/dangerous; is that right?\u201d is the sort of question that I am asked most frequently by pilots who have never flown here. My answer is that hazardous conditions do not arise without a reason, … Continue reading