Thursday, September 13, 2018

Hurricanes Florence and Helene, Tropical Storms Isaac and Joyce, the Gulf of Mexico Blob, and Super Typhoon Mangkhut special: September 13, Update A

Which star constellation does this Constellation of Storms remind you of?
Hurricane Florence: She's currently at 32.5N, 74.3N, heading NW at 17mph. The track is towards the Wilmington area: 
I've heard from a few - some have evacuated, some are staying put. Definitely get out if you are in a flood zone! If you are hunkering down you may be without power for days (or weeks), so be prepared for that. 

The outer rainbands have already reached the coast. The good news is that she steadily decreased in intensity from a cat 4 yesterday and is now officially a cat 2 because of that wind shear:

Winds are officially 110mph, which really makes her a borderline cat 2/cat 3 storm (cat 2 range: 96-110mph), and central pressure is 956mb. The even better news is that the wind shear now looks like it will stay put all the way to the coast, so she may weaken further. I do see that the eye is struggling to maintain itself - if it does go away, then we definitely have a cat 1 storm. So that would be jolly good as far as the wind impacts go. 

But there is still the issue of the water, and in particular, the Gulf Stream...she has to cross this deep warm current. The faster she moves, the less time she'll spend over it. If she does slow down over it, she'll have a LOT of rain. If she takes that curve and moves along the coast just off shore, she'll also have a LOT of rain. We saw this when Tropical Storm Fay (not a strong storm) stalled just over the Florida Current (which is the Gulf Stream off the east coast of Florida) some years ago and dumped a lot of rain over the Melbourne area, causing major flooring issues (if I recall correctly... I could go and read my blog from then, but I'll only find out how boring I am now that I've grown up compared to then, so why bother? :-)). The storm doesn't have to be big or windy to bring a lot of water with it. 

A couple of data resources for you (assuming you have power and time!) to monitor Florence:

1. Storm Surge: to look up the storm surge for yourself in the area closest to you, read the <Technical Alert!&gt in this post which discusses NOAA's unfortunate replacement of their storm surge site tidesandcurrents (, which doesn't load very well for me and is still difficult to use. Currently it looks like the highest is around 0.5ft above normal. 

2. SECOORA resources: SECOORA stands for the South-East Coastal Ocean Observing System Regional Association. This is a collection of off-shore and coastal measurements and models made by a bunch of people (e.g. universities, government entities etc.) - this includes things like winds, water temperature, currents, waves and a whole host of other useful information. (by the way, SECOORA is one of 11 such Ocean Regional Associations around the country). There is a lot of information on this page that they have kindly put together to focus on Hurricane Florence: This includes live-feed cameras (it's nighttime now, so these aren't too interesting at the moment) and other goodies.

Right now for example, the winds at an buoy 27 miles offshore from Wrightsville Beach, NC (run by UNCW) is showing that the winds close to the sea-surface have started to pick up and are just under 27 knots, which is around 31 mph (screenshot):

Hurricane Helene: She has weakend further and will continue to do so. She's currently a mid-sized cat 1 storm with winds of 80mph, central pressure is estimated to be 983mb. She's at 22.4N, 36.9W, heading N at 13mph. The dry air and wind shear continues to be her enemy and she's looking rather worse for wear because of it: 
She's going to continue heading generally northwards, towards the Azores, but will continue to weaken:

Tropical Storm Isaac: Isaac is barely a Tropical Storm now with winds of 45mph, central pressure of 1006mb (TS range: 39-73mph). He's at 15.3N, 58.5W heading W at a very rapid 20mph. He'll be crossing the islands today and be in the Caribbean by this evening: 

He'll be a lovely breeze, bringing with him a nice cooling drizzle: 

If you are on one of those islands, you may not even notice anything much amiss. I don't think he'll even disrupt your umbrella drinking activities. 

SubTropical Storm Joyce: I wasn't even going to bother, except that on the day Joyce is planning to join her big sister, Helene, in the Azores and will arrive about a day or so later...
 Luckily she's a dinky little thing with winds of 45mph. 

Gulf of Mexico Blob: Yes, for those of you who are still awake after all of the above, there is a blob in the southern Gulf of Mexico. There is a very weak circulation signal in the lowest level of the troposphere: 
And an equally weak signal in the mid-troposphere, which is not in the same location because of wind shear. There is some disjointed convection and the NHC give this one a 60% chance of development. 

Stay tuned. Next name is Captain Kirk... 

Super Typhoon Mangkhut: A quick update as this is a big one... it will make landfall in the Philippines at around the same time as Florence in the US. She's now strong cat 4 storm with winds of 150mph (cat 4 range: 131-156mph) and is a very very robust and good looking system:

Ok, that's it for today (a travel day). More tomorrow (also a travel day) when I can. 

Be good out there... don't do anything daft!  
Until tomorrow, 

Twitter: jyovianstorm
These remarks are just what I think/see regarding tropical storms. If you are making an evacuation decision, please heed your local emergency management and the National Hurricane Center's official forecast. This is not an official forecast.

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