Ed DunhamAdministrator
(Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017))
Sat Aug 23 2003 01:20 AM
TD 9 Lost? - Well, Not Yet

I'll offer a different point of view - maybe even a bit controversial because it will fly in the face of Conventional Wisdom but I think that its really what is happening with TD 9.

Without bantering around the topic, I believe that TD 9 is still alive and well - and its still a TD. At 23/00Z I had the low-level center (yep, I think that its still got one) at 17.0N 68.5W. NHC sometimes will hedge their bet a little by 'projecting' the coordinates a little toward where they believe that the center will be at the time of their next scheduled forecast bulletin. Usually this works out okay since the last intermediate position report can always be adjusted in the next 'full update' forecast. But in a weak system, this approach has a flaw in that a LLCC can be lost if you project ahead and the system unexpectedly slows down. I'm pretty sure thats what happened today with the 15Z bulletin. The recon couldn't find anything because it was directed to examine an area which was too far to the WNW of where the center really was. Here's where I think that TD 9 has been over the past 24 hours:

22/00Z 15.1 66.6
22/03Z 15.4 67.0
22/06Z 15.7 67.4
22/09Z 16.0 67.7
22/12Z 16.3 67.9
22/15Z 16.5 68.1
22/18Z 16.7 68.3
22/21Z 16.9 68.4
23/00Z 17.0 68.5

TD 9 really put on the brakes and is currently drifting northwest at 2 or 3mph. Although I don't pay a great deal of attention to them, I decided to take a look at the models and the GFDL really surprised me - so much of a surprise that it looked like an error in the model. The GFDL had brought the TD to just about a dead stop and kept it that way for 5 days. Now when a model is having a rough year verification-wise you don't pay much attention to it, but in this case, I wondered why it would project a stationary storm. So I took a look at the current and projected steering currents where the TD is located and guess what - zero - zip - zilch for many days, and I suspect that the GFDL had picked up on that.

Examining the entire basin, everything has really slowed down, so the upper air forecast models may be on to something. TD 9 may be around (in roughly the same spot) for quite awhile until some other atmospheric change forces some steering currents into that area - and its not even strong enough to create any detrimental upwelling. Okay - its your turn.
Cheers,
ED



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