Friday, July 31, 2020

Hurricane Isaias: July 30, Update A

It's Thursday again, isn't it? Wasn't it just Thursday a couple of days ago? I never can get the hang of Thursdays... they are especially rocky when there's an earthquake (a good pun is it's own re-word by the way). ;-) 

Still, the two pieces of good news from today are that we (humans) have three missions on their way to Mars and, of equal importance of course, that we (the NHC and I) are finally in agreement over Hurricane Isaias!

They increased his intensity, which I fully agree with.... Isaias is now a fully-fledged hurricane. This makes a lot of sense given that there has been a vorticity (circulation) signal in his upper troposphere (sign of a hurricane!) since yesterday. It's still not perfectly round and contained, so a cat 1 seems reasonable - he's currently a weak cat 1 storm with winds of 80mph, central pressure of 995mb (cat 1 range: 74-95mph). You can see that he's got a lot of convection (rain, thunder, and I expect tornadoes in there somewhere) from the infrared satellite imagery:
There isn't a clear eye and the convection doesn't quite wrap around the center fully which aligns with winds around 80mph (and eye starts to appear somewhere around 90mph). 

He is still being impacted by wind shear, which we can see as the clouds stream off to the northeast. And he also still has dry and dusty air ahead of him, which is still keeping his convection in check. 

As for his track, he did turn to the NW overnight/during the day today and he did go over Hispaniola, which is as the NHC forecast. For the most part along the Greater Antilles he wasn't as much of a wind issue as a rain and thundery weather sort of storm. I heard things are ok on St. Thomas, apart from a propane gas explosion that blew up a yacht in a marina earlier in the week (just because this week was going to be slow). 

Once they had the center location, that track forecast improved dramatically. His center is now at 20.4N, 72.2W and he's heading NW at a more reasonable hurricane pace of 18mph. It is a little more straightforward from here on out, so I would agree with the NHC track: 

As he crosses the Turks & Caicos and Bahamas, I expect he will get a little stronger - most likely a mid-to-strong cat 1 (but no more than a weak cat 2). As I said, he has some dry and dusty air ahead of him as well as that wind shear. And if his center goes directly over one of those islands, it will help keep his intensity in check - even just a very little.

That track forecast is now better than any data I have, so I'll go with that. Keep an eye on the entire cone of course, not just the center. 

Also, just in case those of you in Florida haven't seen this yet - your Emergency Managers have been busy working with hotels across the state to set up shelters that allow for social distancing. The link takes you to a website/map with those places. The notice when you get to this site says that all decisions on using those shelters will be made by local emergency managers. 

I think that's almost all for this Thursday. I'm also keeping half an eye on the new Atlantic Blobette that's just come off the coast of Africa - currently around 12.5N, 20W. She has a 40% chance of developing in the next 48 hours. I'm not going to mention her unless she gets a little more robust. 

More tomorrow!

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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