Monday, September 04, 2017

Hurricane Irma and the Hashtag Trailer: September 3, Update A

There are two little things (British understatement strikes again! ;-)) on the menu today... Hurricane Irma (of course!) and I’m proud to be able to share the Hashtag trailer with the world today (please feel free to share if you wish – on social media, it’s #HashtagFilm or please include @jyovianstorm and/or @runicfilms J):

As for Hurricane Irma, she’s now at 17.2N, 51.0W heading WSW at 14mph. Central pressure is 961mb, and winds are 115mph which makes her a weak cat 3 storm (cat 3 range: 111-129mph). They sent a plane in this afternoon and it returned the data this evening and I would agree with these numbers because we can see from both the visible and infrared satellite imagery that she has improved in intensity as she opened her eye a few hours ago:

Interestingly, this increase in intensity corresponds to an increase in water vapour (yes, with a 'u') in the storm, which you can see from this satellite imagery where the green parts show more water vapour in the atmosphere: 
And that, in turn, corresponds to her breaking through that final patch of dry and dusty Saharan Air Layer that I’ve been harping on about for the last couple of days:
So it is no surprise to me that she is now a cat 3 storm - that is as expected. Where I differed from the NHC is that I say she had weakened when she didn't have an eye and only when it began to re-develop did she re-intensify. Makes sense, right? They really should have too because when everyone looks at the statistics of storms at the end of the season, it will be skewed with higher numbers than it should be - it bugs me because it's not scientifically accurate and it's hard to get to the right seasonal conclusions if the data is wrong! Grrr.

Anyway, looking ahead at the intensity, I don’t see much to stop her from getting stronger now… she has a solid structure throughout the troposphere, sea surface temperatures are 27-29 deg C in front of her (for the next day or two at least, and then they get slightly warmer), and she is about to move over water where the upper 100m is warmer than 26 deg C, and there is no wind shear or very dry air to inhibit her development. So I would agree with the NHC from here on, that she will slowly grow into a stronger storm – possibly a cat 4 in the next 24-48 hours. She’s forecast to reach the islands in about 48 hours, on Tuesday evening – and as they are a bit hilly, they will take a little steam out of her.

She is heading WSW (which you can also see in the satellite imagery) and is very fractionally slower than she was yesterday, moving at 14mph:
I definitely do not have the best data for track anymore and would go with the NHC track forecast - it is very good at 1 day out. But I do see a high pressure in front of her, even on that WSW track, so there’s a chance that she will move slightly further south than forecast in the next 24 hours (stay on the southern edge of the cone) or may slow down a bit tomorrow. Of course, I could be way off on this one, so I am curious to see what happens tomorrow! If she slows down, it means she has a bit more time to grow. If she moves southward, then that track at 2 or more days out may shift southward too. Regardless, she is a beautiful big storm as you can see from the overall Atlantic satellite images:
It’s not just about the center of the storm – so regardless of where her eye goes, it will get breezy and rainy in the Antilles... stock up on the ice cream and wine, dust off the raincoats and galoshes!   

Until tomorrow... 
Toodle pip!

Blogs archived at
Twitter @JyovianStorm
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. 

No comments: