Saturday, August 05, 2017

Caribbean and Atlantic Blob: August 4, Update A

May I just say, Cookies and Cream Ice Cream is SO Yummy. J

I see that there are a couple of little Blobs out there…

And now that you know all about vorticity (from the last update), here are the vorticity (circulation) maps at the lowest level of the troposphere and in the middle of the troposphere:

The first Blob to look at is the one in the Caribbean, just off the coast of Colombia (thanks Keith L for catching the original spelling mistake: Columbia is the University, Colombia is the country! :-)). Although there is some convection, which you can see in the satellite image, the circulation (vorticity) is all over the place so for now, I’ll just put this one aside.

The second Blob to look at is the one in the Atlantic – it’s actually easier to spot in the vorticity (circulation) maps than the satellite imagery. It’s the elongated red area just north of 10N, between 25-35W. Again, this is not really well formed yet because it is an elongated region, not confined and round as we expect with tropical storms. Also, the convection is not well developed either, partly because it is surrounded by very dry air as you can see from the water vapour (with a 'u' :-)) satellite image (brown is dry air):

and because it is running into a bit of Sarahan Air Layer:

It will remain suppressed until it clears that dry and dusty air, so it is a little too soon to say whether it will become anything substantial. The key is to look at the vorticity field and watch for any developments there. That it has not really changed much all day however this is one I will keep an eye on.  So, for anyone traveling to a Caribbean region in the next week or two (e.g. me… oopsies :-) or Guy!), there is a chance for development but it is too soon to say right now what that development will look like or where it will go – the pressure field data is pretty poor out there at the moment. I’ll be back tomorrow with a quick update.

But before I go, I think I was going to tell you where to look for those deliciously useful and delightfully colourful vorticity maps for yourselves! Yes... it’s time for the good stuff (&;ltTechnical Alert!&;gt) - good, but not as good as ice cream of course! ;-)


<Technical Alert!> Vorticity Maps: As I mentioned last time, looking at a vorticity (or circulation) map is really useful for figuring out if a Blob is a tropical storm or a low-pressure front. You can find these (along with a whole host of other useful information) at the wonderful University of Wisconsin-Madison's Cooperative Institute for Meteorological Satellite Studies website: Scroll down to the section marked ‘Regional Real-Time Products’ and then find the box that covers the area you are interested in. For the maps that I generally show you, I scroll over the ‘North Atlantic’ box and then click on the ‘Winds & Analysis’ in the drop-down menu. From the top bar, you will see a whole host of options, including the ‘850mb Vorticity’, ‘700mb Vorticity’, ‘500mb Vorticity’, and of course, the top of the troposphere – the ‘200mb Vorticity’. Generally having a quick look at the 850mb (bottom of the troposphere) and 500mb (middle of the troposphere) is enough to get an idea of whether a storm has a good structure or not.

To see how the vorticity has changed over time, at the top, next to the ‘Home’ tab is a ‘Time Step’ tab – you can go back in increments of 3 hours and watch how a storm has evolved. This is how I know that the structure of the Atlantic Blob has not changed very much today. And that’s it. Easy, right? <End Technical Alert!>

Time to get a bit of a nap now. I’ll check in on the Blobs tomorrow and will be back if there is even a smidgen of change.

Toodle pip for now!

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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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