Friday, August 24, 2018

Hurricane Lane - a Central Pacific special: August 23, Update A

Well things are looking brighter today than they were yesterday - unless you are on a few of the Hawaiian islands, in which case things are looking cloudier and rainier today than yesterday. But it's looking generically-speaking brighter for you too!

Hurricane Lane did actually get steadily weaker throughout the day today and is officially now a mid-size cat 3 storm with estimated winds of 120mph (cat 3 range: 111mph - 130mph), central pressure 959mb. And it's great - we can very clearly see the impact that the wind shear is having on him in the satellite imagery:

He's gone from that symmetrical circular shape to an egg shape (technical term ;-)) and the outer band clouds (blue) are streaming off to the north and east. (By the way, if you're looking for Hawaii - it's under all that cloud cover (blue) and rain (yellow)):
There is still a LOT of strong convection and thunderstormy weather in him though - that large area of red in the above infrared images indicates that. He does still have an eye, which is easier a little easier see in the visible imagery (although the light is fading towards the end):
And really great circulation (vorticity) in all layers of the troposphere, so he is definitely at hurricane strength, but with that wind shear being so strong, I think he will continue to weaken.

<Technical Alert!> If you want to see the vorticity (as I mentioned a couple of days ago) and the wind shear, the best place to look is the University of Wisconsin-Madison's CMISS site: Scroll down to the lower map and over the box that covers the area that you are interested in. In this case, the Northeast Pacific. From the drop-down menu you get if you hover your mouse over that area, pick the top one - Winds & Analyses. At the top you will see a bar. Pick 'Wind Shear' and you should see something like this:
Find Hawaii (no, this is not a drinking game!). Just to the south and under all the squiggly lines, you'll see Hurricane Lane as the mass of gray clouds (this is like that picture where everything becomes clear if you squint and turn your head just right ;-)). You'll see it is mostly under some pink lines and some red lines (having moved through the green and yellow lines earlier in the week). The pink lines are the wind shear - the closer they are, the stronger the shear. The red lines are contours and have numbers on them - this indicates the amount of wind shear in that area. And if you haven't squinted too much, you'll notice little arrows on the pink lines - this is the direction of wind shear. 

For vorticity, got back to the bar at the top and you'll see '850mb Vorticity' (for the lowest level of the troposphere), '500mb Vorticity' for the mid-troposphere, and '200mb Vorticity' for the highest level of the troposphere. Here's the vorticity map from 850mb:
Although there is clearly a signal, it's not as round and detached as it was before. Another clear sign that he's weakening. <End Technical Alert!>

He's forecast to be cat 2 storm in 24 hours - and I think he may even drop down to a cat 1. 

He is centered at 17.8N, 157.9W, and is heading almost due north (NNW) at 6pm. 
They think that the track will stay to the south of the islands - this is because he has been staying consistently to the west of the center of that cone. There is a turn expected, as you can see. The reason why the cone is so large is because they don't know quite where the turn will take place - it could get closer to the islands in which case the weather will be worse. I will go with the track forecast as I don't have any data over the Pacific that would be helpful. 

Wine paring for this storm today... he's a little mellower, but still full of flavor. Hmm. Maybe a Chenin Blanc? 

Stay safe in Hawaii my friends. It'll still be rainy and windy and rainy some more! 


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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