Tropical Storm Erin and the Caribbean Blob: August 15, Update A

Today is all about the number 35. I assume you heard the exciting news about the new species of animal that a team from the Smithsonian Institution found in the forests of Columbia and Ecuador, the Olinguito?

It is the first new carnivorous species to be discovered in the western hemisphere for 35 years and is, coincidentally, about 35 cm long. I saw it described today as a cross between a carnivorous teddy bear and a house cat... and all this time I’ve been operating under the premise that my house cats were carnivorous teddy bears!! Well at least that explains why they don’t like being thrown in the washing machine every couple of years, even if they do come out of the dryer fluffier than usual and smelling of fresh grass.

Also in the news today, there are rumours that my all-time favourite sci-fi tv show, Blake’s 7, is going to be re-made! Woohoo! A quality re-make is definitely long overdue!! It first aired in 1978… 35 years ago! J Drat, I should have bought a lottery ticket with 35 on it! Oh well.

I suppose I should say a couple of words about tropical storms now, huh? ;-)  

Tropical Storm Erin

As expected, she was upgraded to a weak Tropical Storm by the NHC and has remained one all day, with winds of 40mph (35 knots!) and a central pressure of 1007mb. She is currently at 15.5N, 29.1W, heading WNW at 15mph. Officially, Tropical Storm force winds extend out 35 miles from the center.

I would agree with the NHC in upgrading her to a named TS (even though they may have been a day late in doing this) and also in their assessment of how weak she was today. However it looks like she has weakened in the past few hours and no longer has very strong convection. There is still some good circulation in the lower half of the troposphere, but it is now connected to a low pressure trough. <Science Jargon Alert!> A low pressure trough is a line of lower pressure and vorticity (<jargon-in-jargon alert!> so very briefly, vorticity is a measure of how much circulation or spinning motion the atmosphere has. <end alert!>) as opposed to a circular area of low pressure (and vorticity). Tropical Storms are circular areas of low pressure. Sometimes you can see troughs in satellite images as lines of clouds, and we have an example here:

If you look at this infrared satellite image of the Atlantic you can see TS Erin at somewhere around 29W, 15.5N, and a line of clouds extending down to her south and west. Ta-da… a trough! J <End Science Jargon Alert!>

I know this is a trough and not a line of clouds from wind shear because there was a bit of wind shear out there but not enough to form this (and also because I looked at the vorticity (I’ll save that for a proper explanation another day). There doesn’t look like there will be much tomorrow either (however it looks like it will increase in a couple of days). Little wind shear means she has room to intensify of course.  Sea surface water temperatures are around 26-28 deg C, which is warm enough to sustain a storm and also allow her to grow. The two factors she has going against her is that low pressure trough and also some dry air to her northwest:

At the moment I would agree with the NHC forecast on intensity (I know, how unusual! ;-)). She will probably strengthen a bit because of the warm water and low wind shear, but in a couple of days she will be in stronger shear and hopefully in a place where there is more dry air, and that will cause her to deteriorate. I think the forecast track may be a little too northward though (according to this she’ll be around 17.5N in less than 24 hours):

I think she may maintain a more WNW track than this indicates (at least for tomorrow).

Caribbean Blob

The NHC downgraded his chances of becoming a named storm in the next 48 hours to 50%, and quite right too. But if you look at the IR satellite image, it would look like he is trying to make a comeback, isn’t he? Looks can be deceptive! The increased convection since yesterday evening in the IR satellite image above is because of the underlying deep warm waters of the Loop Current in the Gulf and not because his circulation has improved. We just had a smattering of rain from this blob up here in St. Petersburg (and quite nice it was too). He is really not very well formed and his center of circulation looks like it is actually over the Yucatan peninsula. I don’t think he will amount to too much once he gets into the Gulf, but it really depends on what shape he is in once he clears the peninsula. At the moment I would say that he would stay in the southern and western Gulf once he crosses, but because he is so weak it is difficult to assess that.

And that’s where we are today. It’s sleepy time here…I shall dream of a brave new world in which there is a brave new Blake’s 7. J

Night!
J.

Blogs archived at http://jyotikastorms.blogspot.com/
Twitter @JyovianStorm

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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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