Saturday, August 21, 2021

Hurricane Henri: 21 August, Update A

A quick note to wrap up Grace and then on to the main story for today, Henri.

Grace made landfall in Mexico just before 1am local time near Tecolutla, Mexico, as a cat 3 storm with winds of 125mph, central pressure 962mb (cat 3 range: 111-129mph). She is now crossing Mexico and has weakened quite considerably - winds are 25mph, so she is not even a Tropical Storm. Her circulation is, however, intact enough that she may re-form in the Pacific. This is my last note on Grace. 

In the Atlantic, Hurricane Henri was upgraded to a cat 1 storm this morning. He is currently at 36.3N, 71.4W heading NNE at the very rapid 18mph, as expected. He is on track to make landfall in the Long Island/Connecticut/Rhode Island part of the world tomorrow:
I would still keep an eye on the Cone of Uncertainty because he could shift within that (to the east seems possible), but at 24 hours away from landfall, the NHC generally do a reasonably decent job with the track and I see no reason why this would change. 

It is still daytime, so this is what he looks like in the satellite imagery by day:

He looks like quite a beast but in a tale as old as time, he's not that ferocious. H
e is officially barely a cat 1 storm with winds of 75mph, central pressure 991mb (cat 1 range: 74-95mph). The intensity is a bit of an overestimate in my opinion. There is still a tremendous amount of wind shear with the clouds streaming off to the south and to the northwest. The NHC think that the wind shear will die down soon, but I am currently not seeing that happening enough to stop those clouds from streaming away. Peeling back what is visible in the satellite imagery above to see what his convection looks like shows us that a lot of those clouds are just clouds or nice rainy weather, and not as much of the heavy rain or thunderstorms we saw yesterday:   

It looks like has run into some lovely dry air again at the lower levels of the atmosphere, which is why the convection took a bit of a nose-dive and has weakened him further. To show you, here is the water vapour at the higher altitudes:

From the top, he looks like he has enough water vapour to keep going, but you can see that dark purple streak coming in from the west - that's dry air and it's at a lower altitude. To confirm that, here's the water vapour from a slice lower down in the atmosphere:

Here we see that not only is there dry air (yellow) on the west, but there is also some to the north as well (yellow/purple). 

He may regain some of that rainy weather and convection, but soon he will cross the Gulf Stream (warm water) and start to move over cooler waters which will make it a little more difficult for him. 

That's it for now, but as it's a Saturday I think you may get another update from me in a few hours. With wine.

For those in the path, be good and be ready, just in case. I hope you have your ice cream supplies... I mean hurricane supplies!

Ciao for now,

ps... New York? Today: Hurricane preparations and a 'We Love NYC' concert in Central Park? You crazy kids! 



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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