Extreme Dutch Weather: Convection rest of May, June and July 2012

Wednesday 8 August 2012

Convection rest of May, June and July 2012

The weeks and months after the awsome supercell at the 10 th of May; went by without witnessing severe weather event. There where a few tornadic and waterspout events seen by others. The high expectations of a few Estofex Level 2 forecasts were several times not 'cashed'. A strong 'CAP' or premature flow of colder western winds spoiled the game.
Here a selection of the things seen in these months. For most situations I was in a 'wait and see modus' @ home and didn't even have to drive that far or at all.....

Pulsating storm near Shell, Pernis: 23-05-2012

Arcus photographed with my compact camera; lucky shot driving work> home: 11-06-2012

Shelf and whalesmouth at the Waalhaven and Maastunnel: 21-06-2012

Golden arcus @ home: 6-7-2012

Nice convection @ home: 11-7-2012

Search for waterspouts near the 'Maasvlakte': 29-7-2012

Some explanation.....

When a thunderstorm has a longer living rotating updraft (mesocyclone) we call it a 'supercell'. A supercell is a relatively rare appearence in Holland; only on a few days a year one or more can be spotted. They can only exist under specific wind conditions. The top of the storm is often not that heigh as that of their bigger brothers in eg. the US. They often bring extreme weather with large hail and even tornado's being possible. A so called 'wallcloud' is a lowering under the stormcloud out of which a tornado can form. The last photo from the 1st of October 2006 shows a wall cloud.

Another type of tornado is not associated with a mesocyclone. It can appear below a stormbase when there are less windy conditions. Although relatively seldom they appear more often than the 'real' tornado. I prefer to call them 'spouts'.

Other weatherphenomena I'm interested in are 'shelfclouds' and 'mammatus' clouds.