Saturday, August 13, 2011

TD Franklin, TD 7 (Atlantic Blobette), and a Blob: August 14, Update B

TS ‘Fake’ Franklin – now Tropical Depression Franklin
As I thought, they downgraded him in the 11pm advisory to a Tropical Depression, sorry a ‘Post-tropical Cyclone’. I’m attaching the IR satellite image so you can have a look at what is left of him - currently he seems to be at around 40.5N, 51.8W, but it’s difficult to tell because he doesn’t have a clearly defined center. That would be because he wasn’t a tropical storm. Also from this image, we can see that his current convection levels are hovering between ‘not much’ and ‘not much at all’.  He is moving ENE at 26mph, winds at 40mph, min pressure at 1005mb.  

Tropical Storm for less than a day. Well done you. This is my second and last update on Fake Franklin.

Tropical Depression 7: Atlantic Blobette

The next one on the list is also on the IR satellite image, centered at around 27.9N, 61.6W. This one looks more like a blobette and has been improving in appearance throughout the day. It’s heading approximately WNW at 10mph, and if you look at what is approximately 360 miles WNW-NW of this blobette, you might be able to see a little white dot… Bermuda.  If this one gets named (which I suspect it will as they now have it in the TS staging area called a Tropical Depression), this will be Gert (I don’t think I’ve heard of an actual girl’s name ‘Gert’. I presume it is short for Gertrude, but a name in its own right? Has anyone else heard of that other than as an abbreviation?).

Circulation has improved in the lowest levels of the troposphere for this blobette, but there isn’t much going on higher up yet.  Winds are at 35mph, central pressure at 1011mb. Convection has also improved during the day for this baby, but it is in an area with some wind shear which is keeping it a little off-kilter. The wind shear looks like it might decrease a bit tomorrow. However, there is something else that is slowing down it’s progression, and has also put the kaibash on the other blobs and blobettes that have been trying to grow up this week. The Saharan Air Layer (SAL) that I mentioned earlier.  I’ll come back to that fun sciency stuff in a moment (I’m building up the anticipation… ;-)).

This is still a very weak system with low wind speeds, just a bunch of clouds and rain really at the moment. I assume the Bermudians are getting ready anyway… ready to go out on little sailboats into the Atlantic and play golf and all the other things they do during a tropical storm….

Atlantic Blob

And again, going back to the Satellite IR image, if you look just south-east of the blobette-that-may-be-Gert, you can see the next potential storm. This one has some pretty decent convection, but not much in the way of circulation at any level. I’ll hold off on saying more about this until the circulation picks up. They have this one at a 30% chance of developing, and the next name up would be Harvey.

Saharan Air Layer (SAL)
So, it turns out that Dust is an agathokakological sort of thing, especially the dust that comes off northern Africa. And of course, agathokakological is a sesquipedalian sort of word… heehee, I hope you all have your dictionaries handy! ;-) (yes, I’m pretty chuffed at using two of them in one sentence!). Ok ok, I’ll give you the agathokakological – this essentially means something that is both good and bad.

The dust that comes of northern Africa quite often travels westward across the Atlantic towards the Caribbean and Florida, amongst other places. This is called the Saharan Air Layer. It has two major impacts. The good one (especially good if you want a social life and are writing a hurricane blog during an active season) is that it tends to suppress tropical storms, in particular it impacts their ability to get their convection groove on. The bad impact is that, amazingly, it carries with it microbes and stuff (technical term for ‘stuff’ ;-)) which has been known to result in an increase of certain health issues along the western side of the Atlantic.

Here is a satellite image that has been worked on a bit to show the Saharan Air Layer:

The red and yellow bits are the dust levels. You can see the blobette and blob, with red indicating areas where you’ll need an industrial strength vacuum cleaner to suck up all the dust, and the yellow areas are places where a feather duster used daily might work ;-).  This image is from the University of Wisconsin CMISS page, which is an excellent website for this sort of handy information! Those of you in the Caribbean know about this, because I’ve heard many of you describe the red layer of dust on your cars when there is a strong SAL.

Oh, I suppose there is one more advantage to dust… if you are on a diet, according to the ‘diet expert’ on Little Britain, you can eat as much dust as you like because it has zero calories. ;-)

Right, that’s it for today. I’m sure it will all be as quiet as a mouse out there tomorrow…


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DISCLAIMER:These remarks are just what I think/see regarding tropical storms - not the opinion of any organization I represent. If you are making an evacuation decision, please heed your local emergency management and the National Hurricane Center's official forecast and the National Weather Service announcements. This is not an official forecast. If I "run away, run away" (Monty Python), I'll let you know.

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