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Precipitation map

The map shows the accumulated 6-hour precipitation. Local deviation will occur because model topography is much smoother than the real counterpart. The map may be read as an indication of weather and where precipitation will occur.

Altitude

Mountaineers are interested in pressure altitude indicated in meters or feet. Meteorologists evaluate parameters like wind, temperature and humidity at constant pressure surfaces. That's why model output is provided at specific pressure levels, e.g. 500 hPa (hPa = hecto Pascals equals mbar = millibars). According to the International Standard Atmosphere ISA you can read 400 hPa as an altitude of 7'300 m / 24'000 ft and 350 hPa as 8'200 m / 27'000 ft. In late spring and early summer pressure altitude is slightly above the ISA values due to thermal expansion of the real atmosphere.

Meteogram

The meteogram shows the evolution of temperature, wind and relative humidity regarding time and elevation.

Ensembles

Numerical weather prediction is a powerful and advanced tool to determine the atmospheric behaviour. Nevertheless a lot of simplifications are needed to calculate the atmospheric dynamics. The initial state of the atmosphere is only known rudimentarily. To cope with this problem, models are run in lower spatial resolution with prescribed deviations of the analyzed fields. The ensemble of results mostly agrees well for some time ahead. After 3 to 5 days differences in weather evolution grow rapidly and show some variance. Forecasters and expedition leaders are mostly interested in the duration of stable weather evolution and in the point in time when model results become doubtful. On this homepage you can study upper level wind speeds and their variance to timely foresee calm periods.