Friday, June 25, 2010

Caribbean Blob: June 25 Update A

I'm a tad busy the next few days, so this is not a good time for a blob to even think about developing! Huh. I'll have a word with Mother Nature and see if I can suspend activity for a week or two. ;-)

I (and others) have been watching this blob over the last few days as it slowly moved across the Caribbean, dumping a bit of rain on assorted islands. It is currently centered somewhere around 16N, 80W, between the tip of Honduras/Nicaragua and Jamaica.

There has been a lot of convection with this system for many days. This is to be expected. The sea surface temperatures in the Caribbean are over 30 deg C (although the eastern Caribbean has dropped by a whopping 1 deg C over the last few days because the blob has cooled things down a little). In addition to warm surface waters, it is now over some very deep warm water -the deepest there is actually. Temperatures are above 26.5 deg C in the upper 125-150m of the water column. If this had been a better developed system, this is the location it would have bloomed into a cat 5! But fortunately for us all, the poor little thing is still struggling to develop ... and in the meantime, it continues to rain and remove some of the heat from the ocean. Yay!

Since the day before yesterday, the lowest levels of the troposphere** (woo alert - see below :-)) have begun to show some signs of improved circulation. It's still quite disorganized though. There is some wind shear. The NHC (National Hurricane Center) have been saying since yesterday that the shear will decrease by tomorrow so the system has a high chance of developing. This is possible, but I'm not 100% convinced the shear drop will be enough.

**Troposphere: this is the name of the lowest level of our atmosphere. It extends up to about 8km height in the polar regions, and 15-16 km in parts of the tropics. In the troposphere, the higher up you go, the colder the temperature gets (e.g. tops of mountains). The next layer up is called the 'Stratosphere'... you might have heard of it because, in the polar regions, that's where the Ozone Hole likes to hang out (and sip pina coladas ;-)). In the stratosphere, the higher up you go, the warmer the temperature gets! Isn't that interesting? The demarkation between the troposphere and stratosphere is called the tropopause.

I'll keep an eye on this blob and write when I can! I'll definitely send another note out on this, once I've looked at possible tracks. My *guess* at the moment is that it'll head W-NW... hopefully to the Yucatan and not into the Gulf!

On another somewhat related note, I've been asked a number of storm/oil questions and just haven't had time to write about them (anyone got a spare day or two lying around that I could borrow? ;-)). I had grand plans to do that in a couple of weeks, but maybe I'll just address a question here and there.

Question: "If there is a storm in the Gulf, will it rain oil on us?"

Answer: I would say no. The rain is from WATER being evaporated from the ocean. Heat energy is used to separate the water molecules (technically called the latent heat of vaporization), which allows the water to go from being a liquid to being a gas (water vapor). The oil molecules will not react the same way ... if I'm wrong and some expert out there knows definitively that they will be part of that process, please let me know and I'll pass along a correction. (And if I'm right, please let me know because then my head can get bigger ;-) ).

The water vapor is carried up into the atmosphere, where the temperature drops (because it gets colder the higher up you get) and the water molecules recombine (condense) to form clouds and then liquid water again (rain). When they recombine, the heat energy that was used to separate them is released into the atmosphere - this is a source of energy into the storm system.

However, if you live in an area where you get sea spray from storms and there is oil in the water, then you will most likely get oil droplets as well, because that is carried 'mechanically' by the wind and doesn't involve breaking up of molecules or other such sneaky things!

Gosh... what a lot of science for a Friday! That should carry you through the weekend. ;-)

More sooner or later!

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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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