Two questions about invests

[dtrain44]

Amid all of the "cancel/don't cancel season" threads lately, a lot of folks have used the frequent, rapid dissipation of invests as evidence to prove various arguments. Being something of a newcomer to tropics-watching, these might not be the brightest questions, but it strikes me that they need to be answered in order to evaluate these arguments.

1) Are there statistics concerning the number of invests that actually develop? For example, is there a database (formal or informal) that would say something like "in 2007, we had thirty five invests, sixteen of which became at least a TD"? If not, what is the sense of pros/experienced amateurs concerning the usual percentage of invests that develop into a TC?

2) Does any government agency produce anything like the watch probabilities produced by the SPC for severe weather watches? (http://www.spc.noaa.gov/products/watch/wwp0701.txt) is an example of this.

Just wondering what a "typical" season might look like in terms of invests so that I might place what I see in context. Thanks!

[Downdraft]

The NRL used to be quite conservative in posting an investiture and because of that many developed. After the 2005 season I guess Katrina scared the hell out of somebody and they became far more liberal in declaring invests. Personally I think before 2005 many developed but now only a small percentage do. I don't think looking at a historical database on development after declaring an invest would be accurate considering the policy of declaring one has apparently changed. Just my humble thoughts.

[dtrain44]

Downdraft, thanks for your thoughts. I think it makes sense to be fairly liberal on declaring an invest, seeing as the basic idea is to make sure that you aren't caught unawares and that you can get more warning on a potential TC. But you're right that it would skew the data if NRL has changed dramatically. I think the point I raised in my second question would really help with an issue like that: veteran weather watchers know that when the SPC uses phrases like "high risk", "particularly dangerous situation", and "large, destructive tornadoes", they mean business. Perhaps we're just not at a point with TC formation that we can understand and predict it as well as we can predict a severe weather outbreak.

Regardless, as an amateur, I'm blown away by how good the pros are at this sort of thing.

[Chacor]

NRL isn't the one that declares invests, it's either the DOD (and by extension JTWC) or DOC (and by extension the TPC/NHC).

[dtrain44]

Chacor, I didn't realize that. Thanks for the clarification. Can you speak to Downdraft's point about any changes in the propensity of those agencies to declare invests?