Saturday, September 12, 2020

Tropical Storms Paulette and Rene, Tropical Depression 19, and assorted Blobs: September 11, Update A

OK, I think we've had enough art from the NHC this year. My fridge doesn't have any more room to put them up so you can put your paint brushes away now. Really. 

And if you wanted to know what that looks like 'IRL' (In Real Life)... here's the corresponding satellite imagery across the Atlantic: 

Tropical Depression 19

Starting with the one closest to land... yesterday this officially had a 10% chance of developing in the next 48%, but I suppose that's the probability for everything in 2020 so I should have paid more attention! It's at 25.7N, 79.8W, heading WNW at 8mph and is already bringing a few drops of rain over the Bahamas and southern Florida. 

It's winds are 35mph, central pressure is 1007mb, so it's not a Tropical Storm. There is some circulation in the lower half of the troposphere, but not very strong, so I agree that this is a Tropical Depression at the moment. It's tricky to see the center where they say it is from the satellite image... 

That's because there is some wind shear which is pushing the convection to the south. From the imagery and the vorticity maps, I'd say the center is a little south of the official location. However, they got the center from the Miami radar, so I'll go with that. 

This part of Florida is quite soggy (Everglades), so the land interaction won't really stop this one from developing slowly. It is also over some very warm water - 30 deg C - which will also help in the slow development. However, there is a bit of wind shear over the southern point of Florida, so that will stop her from rapidly developing. Still, I think they'll name her tomorrow. The next name is Sally. 

Tropical Storm Paulette

She's at 25.8N, 54.8W, and continues to head NW but at a faster 16mph. Regarding the track - she can go anywhere in that cone, so don't just focus on the middle part (unless you live on Bermuda, in which case, you probably should focus on that middle part!). 

Winds are now a little stronger than yesterday at 70mph, central pressure is 987mb, which makes her a very strong Tropical Storm (TS range: 39-73mph). There is still some wind shear which we can see as the clouds continue to drift off to the north east in the satellite imagery above, but she should start emerging from that tomorrow, so I can see why they say she'll be a hurricane soon. The current NHC forecast is for a cat 2 storm with winds close to 100mph as she passes Bermuda on Monday morning. 

The vorticity maps show a strong circulation in the lowest level of the troposphere (850mb):

And in the mid-level (500mb): 

The upper level (200mb) is interesting - she is actually on the edge of an upper level low pressure trough, which you can see sweep around and to the east, so she's not quite a hurricane yet. 

The one thing that will keep her in check once she clears the wind shear is dry air, but it doesn't look like it will last all the way to Bermuda... 

Bermuda peeps - after you've secured your boats, don't forget to secure the car... I found this helpful photo...

(Image from the Bermemes website) 

Tropical Storm Rene

He's still chasing after Paulette, but not very successfully. He's barely a Tropical Storm with winds of 40mph, central pressure of 1004 mb. But he is still one because there is circulation in the lower half of the troposphere. However his convection is struggling to take hold because of dry air and the NHC expect him to become just a TD by Monday evening as he will also be in some wind shear before then. He's at 21.4N, 42.4W, heading WNW at 14mph. 

I think I'll stop with the Rene updates after this one as he's 'Mostly Harmless'. But if he doesn't behave, I'll have a few more words to say. 

Atlantic Blob - the red one

This is the one that came Out of Africa a couple of days ago. There is some circulation in the lower half of the troposphere, but it is part of a much larger area of activity as we can see in the vorticity maps, so it's not quite the structure of a Tropical Storm yet. This has an 80% chance of developing into something in the next 48 hours. It is currently moving westward at 15-20mph. 

Atlantic Blob - the yellow one

This one has a 20% chance of developing into something in the next 48 hours and is moving generally westwards. The vorticity appears to be connected to the other Atlantic Blob, so it really isn't very well developed at all. 

Gulf of Mexico Blob

This one also has a 20% chance of development and is moving generally westward. It may have some showers but you can see that it doesn't have much circulation at all from the vorticity maps. So not really much going on here. 

Did I miss any? Headcount... ok, good, all the kids are accounted for. Phew, I'm glad I went shopping yesterday and got two more tubs of ice cream and re-stocked on wine. It looks like it may be a silly sort of looong weekend... ;-)

Ciao for now,


Twitter: jyovianstorm

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 local 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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