Cloud liquid water path (LWP) is an important parameter to validate forecasts obtained from circulation models of high spatial resolution. At present, it is not measured on a routine basis. Being part of the Advanced Very High Resolution Radiometer (AVHRR) Processing scheme Over cLoud, Land and Ocean (APOLLO) a parametrization scheme to derive optical thickness from cloud reflectance and, further, the LWP has been adopted and adjusted to AVHRR channel-1 counts. From these counts, top-of-atmosphere bidirectional reflectance data are obtained. Using APOLLO-derived fully cloudy pixels only, the directional hemispherical cloud reflectance is derived to which the parametrization scheme refers. The LWP of each fully cloudy pixel is determined. As a first application, the mean LWP of 63-5 × 63-5 km2boxes is computed and compared to a 14-hour forecast of the LWP made with the Europa-Modell of the Deutsche Wetterdienst. The location of the clouds seems to be forecasted rather well by the model. However, the LWP computed by the model is higher (by a factor of 4 or 5) than that derived from AVHRR data using APOLLO. A first validation by means of aircraft measurements shows that the APOLLO-derived LWP is too low by about 50 per cent. This reduces the discrepancy to the computed data but the model predicted LWP still seems to be too high by a factor of 3.