Sunday, August 28, 2016

Hurricane Gaston and the Atlantic Blobette and Atlantic Blob: August 27, Update B

Before we delve into the 'slightly busy' Atlantic, I know many of you have pooches. So, in honor of National Dog Day in the US yesterday, this...  
:-) (from Crufts 2012 dog show I think, photo credit: Reuters)

Hurricane Gaston
He did become a hurricane and now has winds officially at 85mph, central pressure of 980mb, which makes him a mid-sized cat 1 (cat 1 range: 74-95mph). He is currently at around 29.6N, 54.2W, heading NW at 8mph. If we look at his visible and infrared satellite images, we see that an eye is developing, which would happen around 90mph, so I agree with the NHC on his strength:

The circulation is very strong in the lower half of the troposphere, and there is a small signal in the upper troposphere, although it is attached to a trough - an elongated area of vorticity. A signal that high in the troposphere does suggest a hurricane, and given that it is not strong yet, this is another clue that this is a cat 1 storm at the moment. As he moves into that area of elongated upper tropospheric vorticity, there is a good chance he will get stronger.  

Another reason he may continue to strengthen a little is because wind shear is relatively weak at the moment and he is over very warm sea surface temperatures - over 29 deg C - with the upper 50-75m warmer than 26.5 deg C. However, it looks like the wind shear may get a bit stronger in a day or so, which may at least slow his growth. 

It looks like Gaston is on track to move to the North and then the Northeast by Monday. 

Atlantic Blobette
The Atlantic Blobette is still struggling as far as her convection goes, because she is still interacting with Cuba:

However, her circulation in the lower troposphere has improved since yesterday. She is in relatively weak wind shear and it looks like it will remain weak in front of her. The water temperatures ahead of her are very warm, with surface temperatures greater than 30 deg C and the upper 100m in the Straits of Florida warmer than 26.5 deg C. The thing that is really inhibiting her growth at the moment is Cuba. Although she is weak and messy, I think her circulation is centered somewhere near the northern coast of Cuba. If she retains her circulation once she moves away from Cuba, and if all other things remain the same, it looks like she will intensify into a Tropical Storm. Looks a bit rainy out there! 

Regarding the track, I have been reunited with my pressure fields (although the NOAA page links still don't work!). It looks like she'll continue in a WNW-NW direction for now, along the northern edge of Cuba. 

Atlantic Blob
And then there's the Blob near Bermuda. The good news here is that although there is circulation in the lower levels of the troposphere, there isn't much in the middle or higher troposphere. The convection is also very weak:
The only reason to keep an eye on this for a little while longer is because it does have that low-level circulation (vorticity). We'll see how he is doing tomorrow. 

I think that's it 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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