2nd March 2004: 00UTC
The set of images comprises of 3-hourly IR images with surface observations superimposed. All the weather events are represented by a colour-symbol listed below. The first image shows the cloud spiral in modest size after it came down from the Atlantic and is now situated over northern Norway and Sweden. The cloud head can easily be recognized with an associated but isolated report of snowfall.
2nd March 2004: 03UTC
At this timestep the cloudspiral has increased in size and has displaced South-East. An increase of convectivity is not reflected in more precipitation. Snow is reported in the cloudtail, untypical for a comma like cloud.
2nd March 2004: 06UTC
The cloudspiral has increased in size. A small comparison to the IR image of 3 hours earlier reveals an increase in brightness. Cold cloud tops can be recognized in IR imagery. The increase is also well reflected by the now numerous reports of snowfall reported throughout most of the spiral.
2nd March 2004: 09UTC
The convective character discussed already in earlier sets of images is reflected by the reports of snow. In the cloudhead also hail is reported.
2nd March 2004: 12UTC
The convective character discussed already in earlier sets of images is reflected by the reports of snow. The tail of the spiral seems to be the most weatheractive with precipitation in form of snow and rain.
2nd March 2004: 15UTC
The spiral still increases in size. The appearance in IR imagery of the spiral is pronounced. Snow is reported over a widespread area.
2nd March 2004: 18UTC
From West to East a gradient of white to grey can be observed in the spiral. Where as the rear edge of the spiral shows the brightest pixel values (coldest cloudtops) also the most reports of snow is at this side of the spiral.
2nd March 2004: 21UTC
The same process described for 3 hours earlier van be stated here as well. A gradient from white to grey can be observed. Most snow is reported in the brightest part of the cloud spiral.
3rd March 2004: 00UTC
The last image of this set reveals the Spiral as it covers most of Poland, the Baltic States and southern Finland. In the tail the precipitation is mostly in form of snow and rain. Over Finland the precipitation reported is snow. The continuous increase of size has weakened the level of convectivity. Over the past few images the appearance of the spiral has decayed. This is also reflected by the reports of hail. Last hail report was 12 hours earlier.
