Melissa Moon
EF5
Originally posted by Jeff Snyder
I don't see how high instability can cause more storms to form. The number of storms that form is more due to the opposing combinations of forcing and capping. If there is too much forcing for the given cap strength, you'll get plenty 'o storms; if there isn't enough forcing for a given cap strength, you'll get a big 'o bust. In either case, you still need a source for surface convergence in order to initiate an updraft. There can be 10000 j/kg CAPE, but the balance between forcing and cap strength (or CIN I suppose) is what usually dictates surface-based convective coverage. For the example of high forcing, low capping, the degree of instability will just give you a clue about whether you'll have a line of showers or a raging bow echo. Likewise, for the too little forcing for the given cap strength, it doesn't matter if you have 100 j/kg CAPE or 5000 j/kg, because that surface parcel just isn't going reach the LFC. High CAPE will likely cause high updraft acceleration, but I don't see how the presence of strong instability will initiate new convection by itself...
P.S. -- Just remember, you don't need a decent cap to keep supercell discrete.... The May 3rd, 1999 outbreak in Oklahoma was characterized by only a weak cap...
Perhaps I should have reworded what I was trying to say earlier...I'm bad at picking the correct terminology to make my point, even if I know in my head what I am saying. What I was trying to say earlier is that we have (or had...I haven't looked at the latest runs) those great CAPEs progged over such a large area, and my fear is that the cap is not going to hold up well over a large area (kind of like a few weeks ago) and, as a result, everything will fire up at once rather than having a few supercells that can get a healthy moisture feed. You're right that it is still possible to get discreet supercells from a weak cap, and that could happen too.
I'll be the first to admit that there's a lot of stuff I still don't know that I am learning as time goes on, so forgive me if I say something stupid or inaccurate. But anyway, I don't know if this is something that should be worried about, since I haven't looked at the latest data/runs/etc. , but I hope that clarified what I meant when I made that statement yesterday.