Clark
(Meteorologist)
Sun Aug 15 2004 05:46 AM
Re: news coverage

javlin - yes, somewhat. Midlatitude (cold-core systems) tend to be of a more baroclinic nature, while tropical systems are closer to barotropic. Deals with how the systems grow, in laymans terms. It's tough to explain without going into atmospheric dynamics and could take 20 pages, neither of which I'm about to do!

BillD - I agree, though I'd tend to believe the models right now just because they are so tightly clustered. I'll buy recurvature; I don't know that I'll buy it within the next few degrees of longitude. By 50°W, sure; just after 40°W, I'm not so sure. Ultimately though, I think it's a fish spinner, leaving the intensity question to be the last unanswered question.

Also saw a question about the Dvorak technique. Not sure how much depth the links went into, but in a quick summary, the Dvorak technique was established many years ago to classify tropical systems and their intensities based upon observed satellite patterns. It splits tropical cyclones into a few major cloud-organization categories - I don't recall the exact ones, but there's a spiral band category, a CDO category, and I *think* a sheared category - and allows an intensity for each to be obtained based upon how well a given system matches the expected cloud organization structure for that type of storm. It's a good estimator of intensity, but as we've seen not necessarily an accurate one. It is not good with rapidly developing storms, for instance, as we saw with Charley (highest estimate of T5.0, or 90kt).

A couple of observances on the tropics...

* The models I have seen lately take Earl a bit further south than Charley. The storm does continue to become better organized and I do not think it will be a storm that struggles to get it's act together over the Caribbean. The current steering flow should keep it on a west to west-northwest motion throughout the forecast period, albeit I think probably at a faster rate initially than the NHC is calling for. The strength of the next East coast trough will determine it's ultimate fate - Mexico/Texas or eastern Gulf. Current projections say it may well be weak enough to not have much of an influence on Earl, but that's five days away. The G-IV will be headed out to Earl in a day or two, which should help to refine things. No sense in predicting a track beyond saying it should be somewhere near Jamaica in about four days. Intensity? All factors seem to be favorable, save for the fast motion, for some strengthening. Hurricane status is almost assured; wouldn't be shocked to see a cat 2 or 3 in four days.

* Danielle continues to become better organized and, while this may sound like a broken record, major hurricane status is not out of the question for this one either. The next day or so will be critical; the further west it gets before recurving, the stronger it gets. Imagine the eye will pop out on the first few visible images of the day in the east Atlantic - it's a classic Cape Verde storm, but also a classic fish spinner.

* Wave train over Africa is well established, but we may see a brief lull of a wave or two after Danielle moves away. Waters out there aren't *that* warm yet and the strengthening of Danielle is going to churn them up just a bit. It's folly trying to predict storm formation (or no formation) from something over the middle of Africa, but I think we'll have a few days' respite before the next waves get cranking in the east Atlantic.

* Those of you in the Tallahassee area interested in seeing some Bonnie or Charley video in a couple of weeks, feel free to PM me and I'll fill you in on the details. Our local AMS chapter should be showing some video of Bonnie's onslaught and Charley's aftermath later this month.



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