typhoon_tip
(Meteorologist)
Sat Sep 01 2007 05:11 PM
Re: Area of Interest - Invest 98L

Suspect this thread will eventually need to get bumped to the Main Page agenda...

Firstly, in case anyone is wondering: The models may not pick up on this disturbance very well. I'd count on disappointment if you are hoping to see multiple contours of MSLP modeled illustration at anytime soon.

Just as was the case with Felix and the differences between Felix and Dean's seeds, there is no certainty that the genesis phase of the any given TCs life will even been seen. Dean was, Felix on the other hand had a labored appearance in the models at best. In fact, a few models may be retarded on Felix's intensity as it gains longitude, for that matter...constantly playing catch-up for those models that are still a bit behind what is already verifying... (55kts, not bad).

But, as far as 98L goes, currently, visible imagery provides a rather conspicuous cyclonic gyre along the TW axis, and of course, it is plainly obvious that convection has increased signficantly in the last 12 hours. This system actually maintained a tiny convective plume during its entire voyage, which really came off of Africa slightly N of its previous siblings. One of my personal druthers with these things is that I really like to see the convection more than the turning... I have seen large dry TWs with clear rotation trundle the entire distance of the Atlantic Basin and never do diddly, about as often as I have seen small convective sneaky entities wind up TCs.

The dry air that has been plaguing the 25N/30-60W regions of the Basin is also showing the presents of this TW now, having a surrounding circumvallate of increased theta-e now seen in vapor imagery.

http://www.ssd.noaa.gov/goes/east/catl/wv-l.jpg (I would have just posted the image but it blocks to largely)

The upper air analysis looks a little shaky with some ESE shear in the area as of this morning. However, out ahead of the TW conditions improve quite a bit, with generally a lighter easterly component in the 300mb and 200mb levels... This means that as TW enters that region, its relative shear (environmental wind speed - minus system forward speed) drops off; and if convection is on-going, that would induce a more radial outflow in that type of antecedent environment. This better environment can be seen in the 200mb streamline analysis...

http://www.nhc.noaa.gov/tafb/QHQA17.jpg

which shows what a appears to be a very enhanced divergence and a COL coupled between approximately 45 and 50W, by 15N, due in the path of 98L's current trajectory. This is important because the modeling of the GFS at 300mb for this region is showing this to be in no hurry to decay in structure. Should a fledging TC or TD get up underneath that it would easily tap into those favorable mechanics and probably get a pretty good assist.

All together, I think there is definitely potential for this system to develop further.



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