Moeilijk om zekerheid te krijgen over 'supercel' of niet
Bericht van: Ben (Lelystad) , 08-08-2012 10:23
Dit schreef ik op een Engelstalig forum over de bui bij Steenwijkerwold:
,,Given the estimated atmospheric conditions near the storm, I would say that the odds of the storm being a supercell (for a short or somewhat longer time) are quite good. There is no argument about what we would likely expect to see. However, there is no real qualitative or quantitative evidence that rotation -did- occur. Meaning: there is no direct evidence that this was a supercell, only a likelihood with unknown (though probably high) value.
Perhaps I am just being a bit harsh here, but I am somewhat worried that (especially among weather enthusiasts, but among professionals as well) the threshold for likelihood becoming synonymous with certain occurrence may be decreasing or becoming entirely foggy. When do we proclaim a storm to be a supercell, only based on its likelihood? How do we determine or perhaps calculate that likelihood? We know that supercells can occur under a wide range of atmospheric conditions. This complicates things a lot.
I agree that streamwise vorticity when tilted vertically by an updraught leads to rotation around the updraught axis (vertical vorticity).
However, how much rotation -has to occur and for how long- to call a storm a supercell, and -in this case- how much rotation and for how long did it actually occur? IMHO the latter questions cannot be answered without doppler radar imagery or (convincing) photographic or video material at various stages in the lifecycle of the storm. Perhaps that is my strongest 'objection' (or pet peeve, perhaps) toward quickly calling a storm a supercell, which often comes across to me as overly definitive and without serious merit.''
Kortweg: de aannemelijkheid dat een bui een supercell kan zijn, wordt mijns inziens soms te snel synoniem met 'het was een supercell'. Zonder duidelijk bewijs in de vorm van foto's of videobeelden (afgelopen dagen is dergelijk materiaal van bepaalde buien wél gezien) of doppler radarbeelden, blijft het eigenlijk speculatie. Inzake de bui bij Steenwijkerwold heb ik geen beelden gezien van rotatie, noch doppler radarbeelden met een snelheidssignatuur dat duidt op rotatie. Daarmee is die bui hooguit een 'verdachte cel', maar geenzins een vastgestelde supercell.
Gr. Ben
,,Given the estimated atmospheric conditions near the storm, I would say that the odds of the storm being a supercell (for a short or somewhat longer time) are quite good. There is no argument about what we would likely expect to see. However, there is no real qualitative or quantitative evidence that rotation -did- occur. Meaning: there is no direct evidence that this was a supercell, only a likelihood with unknown (though probably high) value.
Perhaps I am just being a bit harsh here, but I am somewhat worried that (especially among weather enthusiasts, but among professionals as well) the threshold for likelihood becoming synonymous with certain occurrence may be decreasing or becoming entirely foggy. When do we proclaim a storm to be a supercell, only based on its likelihood? How do we determine or perhaps calculate that likelihood? We know that supercells can occur under a wide range of atmospheric conditions. This complicates things a lot.
I agree that streamwise vorticity when tilted vertically by an updraught leads to rotation around the updraught axis (vertical vorticity).
However, how much rotation -has to occur and for how long- to call a storm a supercell, and -in this case- how much rotation and for how long did it actually occur? IMHO the latter questions cannot be answered without doppler radar imagery or (convincing) photographic or video material at various stages in the lifecycle of the storm. Perhaps that is my strongest 'objection' (or pet peeve, perhaps) toward quickly calling a storm a supercell, which often comes across to me as overly definitive and without serious merit.''
Kortweg: de aannemelijkheid dat een bui een supercell kan zijn, wordt mijns inziens soms te snel synoniem met 'het was een supercell'. Zonder duidelijk bewijs in de vorm van foto's of videobeelden (afgelopen dagen is dergelijk materiaal van bepaalde buien wél gezien) of doppler radarbeelden, blijft het eigenlijk speculatie. Inzake de bui bij Steenwijkerwold heb ik geen beelden gezien van rotatie, noch doppler radarbeelden met een snelheidssignatuur dat duidt op rotatie. Daarmee is die bui hooguit een 'verdachte cel', maar geenzins een vastgestelde supercell.
Gr. Ben
