Saturday, August 25, 2018

Tropical Storm Lane - a Central Pacific special: August 24, Update A

Aloha out there! Hurricane Lane is now Tropical Storm Lane! Hurray! 

That wind shear definitely took its toll and his winds are now 70mph (TS range: 39-73mph), central pressure is 985mb. Although he's only just below a cat 1, he's clearly in a much nicer category for all concerned and for those beautiful islands:

It looks like he's just about started to make the turn from heading almost due north, to now heading NW, although his speed is a very slow 3mph. His forecast continues to show him turning and heading west: 
But despite this weakening storm and the turn to the west, the islands are still going to get a bit more rainy weather because he's still got some circulation in the lower half of the troposphere, and there's still some convection, which is being swept to the northeast (and over the islands) because of the wind shear:

He'll continue to sputter on for a few days, but he'll remain in that area of strong wind shear, so I don't think he'll be bouncing back. I'll keep an eye on him in case something wonky (technical term! ;-)) happens, but for now I think it looks like this will be my last post on Lane! 

Next up in the eastern/central Pacific would be Miriam, and next in the Atlantic will be Florence. 

Wine pairing for today's version of Lane. I'm thinking definitely lighter-bodied but still fruity - a Pinot Noir perhaps. :-) (you know, one of these days I'm going to get my storms and wines all confused and then I'll be talking about Hurricane Merlot or Tropical Storm Barbera). 

Stay safe out there!
Ciao for now,

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.

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.

Thursday, August 23, 2018

Hurricane Lane - a Central Pacific special: August 22, Update A

Aloha! The story so far... another beautiful day on Oahu today...
(photo credit: Malia M.)

Meanwhile, off in the distant south, Hurricane Lane is still a pretty good looking, decent cat 4 storm with winds estimated from satellites to be 145mph, central pressure of 939mb (cat 4 range: 131 - 156mph). Given his vorticity structure (which you know all about now - if you don't read yesterday's post! :-)) throughout the troposphere and his current satellite appearance, I think he's a little stronger than this, but there are factors that are coming into play that will hopefully weaken him a little over the next couple of days. 

He is currently at 15.9N, 156.5W and about 260 miles south of the Big Island, so he still has a way to go to get there. He's moving NW at a slightly slow 8mph:
The good news (so far) is that he has been moving a little more to the west of the center of the cone so the forecast is that he won't be a direct hit on the Big Island, however they will still get some strong winds and they are already collecting a few bucket-loads of rain. In addition to the rain, storm surge will be high on the south and west coasts because winds move in a counter-clockwise direction around a low pressure system (which is what a hurricane is), so as he passes by to the west, he'll also be pushing water on shore. 

Because he isn't going to be as close to this island, it won't have as big an influence on reducing his intensity as it looked like with yesterday's track. However, the wind shear is still in place and the main convective area should start to interact with that in the next 24 hours - by tomorrow we should see begin to see some of the effects of that in the clouds on the satellite image. For today, he is still looking good:

You can see some of the wind shear taking hold of his outer rain bands - the clouds that are streaming off to the north and then being carried away to the east. 

Tomorrow I think we should begin to see a gradual weakening but I think he'll still be a cat 4 tomorrow, despite the wind shear. One thing that will sustain him is that the ocean is quite warm, and he's about to move into an area where the upper ~100m of water is warmer than 26 deg C - which means he has enough fuel to sustain him. The competing influences of the ocean and atmosphere will only very slowly decrease his intensity.  

And now for a new feature (thanks to Aida A. for the suggestion)... a wine-paring to go with this post. Hmm... Lane is a full bodied, robust storm that is being a bit of a nuisance to some very nice islands, so I am not a huge fan of him... I think that'll be a Shiraz! ;-) 

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.

Wednesday, August 22, 2018

Hurricane Lane - a Central Pacific special: August 21, Update A

Eesh. Mr. Hurricane Lane! Well the good news for today is that my on-the-ground reporter, Malia M., said this morning that the surf was pretty good on the north shore of Oahu and it was a lovely beach day today. 

But we can see that Lane is slowly creeping towards the islands. He is currently at 14.5N, 154W, and has started that curve to the north. He is heading WNW at 9mph. The overall track has shifted to slightly to the north, but there is still a large range of uncertainty so keep in mind that he could go anywhere in that cone: 

Unfortunately, he did get stronger during the day and is now a cat 4 storm  with winds of 160mph (cat 5 range: >156mph). The data is extracted from hurricane hunter planes, but his satellite imagery also supports a robust storm. We can see a really good, solid, clear eye that has been in place all day. The infrared imagery also shows a very large band of very strong thunderstorms around the eye (the red part):  

The water vapor imagery shows the overall cloud structure more clearly and we can see a good outflow (that curved 'sawtooth' pattern) on the west and north side of the storm, which is another sign of a well developed storm: 
The final clue that he is a solid storm is his vorticity (circulation), which is is also very well strong in all levels of the troposphere. I think it's almost time for an exciting <Science Alert!> on Vorticity, but before I jump into that, a few more observations on Lane and Hawaii. 

Although the track is looking a little dodgy for the Hawaiian islands and he is the strongest storms that has passed this close to Hawaii for decades, there are a few things that may reduce his intensity before he gets close to Oahu (at least):
1. There is still some wind shear between him and the Big Island. It's may keep him slightly in check, although he is strong so it won't be as big an influence as it would be on a smaller storm, but it will be something.
2. He will interact with the Big Island of Hawaii, which has mountainous terrain, which will keep him in check and may reduce his intensity as well. The outer bands have already started to cover this island, with some light rain on the southern and eastern shores:
This poor island! I can see the movie titles: Battle of The Natural Disasters! Or stay tuned for Lane versus the Volcano!
3. As he interacts with the other islands before getting to Oahu, his intensity will also be kept in check and maybe reduced. The extent of how big an impact this will have depends on how close his center gets to the other islands. 
4. Finally, his track may keep him to the south of the islands entirely - that cone is still very wide. 

If you are on the islands, remember:
1.  Run from the water, hide from the winds. This means that if you are in a place that will flood, move inland. If you are in a place that won't flood, hunker down. The greatest loss of life in a storm is from water - storm surge, flooding from rain and rivers etc. 
2. Be careful after the storm - downed power lines and water don't work well together so be careful where you walk. 
3. Get supplies for a few days (more than 3) - if you are in a place where the roads are small, they may be impassable from debris. If the power is out, then you may be stranded for a few days until help arrives. (Get some ice cream in too - if the power goes, you'll have to eat it first and it will keep you cool as well. That's my solution to many things. :-))
4. Listen to your local emergency managers - they have the best information for your locale!

Ok, now for a fun bit-o-science! Are you ready? :-) 

<Science Alert!> Vorticity: A storm has 'circulation', and it's pretty obvious what that is, right? It simply means that a storm is going around a central point, like a carousel. Well, vorticity, is essentially the way we measure the amount of circulation that a storm has. It's a very useful tool and I've used it for ages - next to a corkscrew for opening yummy wine bottles, it's my favourite (with a 'u') tool during hurricane season. ;-)

Although satellite imagery is one piece of the puzzle, the biggest clue about what sort of storm we have is the vorticity and what it looks like in different levels of the troposphere, because that gives us a glimpse into the structure of the storm. 

All types of stormy weather have a recognizable vorticity signal in the troposphere. Like a fingerprint, you can figure out what sort of storm system you have if you know what and where the vorticity is. The vorticity for low pressure fronts looks different compared to tropical storms. For low pressure fronts, the vorticity stretches out in a long line. For proper, grown-up, tropical cylones, the vorticity is confined and generally circular. 

You can also tell how strong a tropical storm is depending on how strong the vorticity is and how high into the troposphere that signal can be seen. A Tropical Storm ALWAYS has a vorticity signal that reaches the middle of the troposphere (around 500mb) because this indicates that there is some deep convection (aka big thundery clouds). <End Science Alert!>

So lets look at the Pacific and Hurricane Lane. Here is the vorticity map for 850 mb (the lowest level of the troposphere): 

You can see the signal of Hurricane Lane just south of Hawaii - the big red splodge (technical term), conveniently covered by a hurricane symbol. 
Here's the map for 500mb (the middle level of the troposphere):

In this, you can still see a nice round, red splodge in the same place as the 850mb level map. You can also see another red splodge to the northwest... but this second one isn't a hurricane because there isn't any circulation in the lower level of the troposphere. It's just in the middle levels that there is some movement.  
And here's the map for 200mb (the upper levels of the troposphere):

In this upper level map, you still see a very nicely defined Hurricane Lane vorticity signal - still orange/red, which means that there is some good circulation throughout the troposphere - we only see a signal of vorticity in this upper level if a tropical storm is actually a hurricane. And the stronger it is up here, the stronger the hurricane. Meanwhile, that other red splodge doesn't have a corresponding signal this high up. But instead, we see a lot of lines - there is vorticity up here, but it is more like low pressure fronts (troughs). 

These amazing maps are produced by the University of Wisconsin-Madison's Cooperative Institute for Meteorological Satellite Studies - and a jolly good job they do too! I'll talk about how you can access them for yourselves in a future post. 

I think that's it for now. Get ready and be prepared my friends in Hawaii! 

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.

Tuesday, August 21, 2018

Hurricane Lane - a Central Pacific special: August 20, Update A

G'day! Surprise! I'm doing a special set of updates on Hurricane Lane in the Pacific. Hurricane who??  You know, that good looking category 4 storm that is heading towards Hawaii this week. I know, I know, I ignored the last two storms in the Atlantic (TS Debby and TS Ernesto) but really, they were just hanging out, far-ish from land, not causing too much of a ruckus. And besides, I was hanging out with the Kangaroos and Koalas in Australia, over 19,000 miles away (typical...of course Debby would pop up when I'm traveling). 

But Hurricane Lane is a different beastie from the gentle Debby and Ernesto. He's seriously thinking about visiting Hawaii to personally check out their volcano and their emergency alert system. Poor Hawaii - they have had a bit of a rough year!

Hurricane Lane is currently at 13.8N, 150.4W heading W at 12mph. His winds are officially at 130mph (cat 4 winds: 130-156mph), central pressure is 964 mb. This makes him a weak cat 4 storm. He has a pretty decent eye, which you can see in the visible, infrared, and water vapour satellite images (and may I just say how it warms me heart to be able to access these sorts of satellite images for the Pacific at least (too bad about the mess in the Atlantic) - it makes it much easier to get an idea of what is going on!!):

From these, and looking at his vorticity (circulation), I would agree with the NHC that he is a borderline cat 3/cat 4 storm. The infrared shows that he has some strong thunderstorms (the red areas) and the outer bands are not too far from the big island - they will get there within the next 24 hours:

His track is the big question... currently the forecast has a very large range: 
and the Cone of Track Uncertainty touches all the islands. For the first time in history, a NOAA hurricane hunter plane flew into a storm in the Central Pacific - this is great because it provides some desperately needed data from within the storm that feeds into the models, which help the forecast. However it isn't enough to really refine those models. Actually, this is a global issue - there simply isn't enough data over the ocean to be able to really get a good forecast (but stay tuned because we have an XPRIZE competition percolating to try and get a solution to this - although it won't be for this year!).

At this point (Monday evening) it is really too soon to tell if he will take the northernmost track in that cone, or pass to the south of the islands. But I do see a glimmer of good news -  there is some decent wind shear between Mr. Lane and Oahu, so he should at least be weaker if he heads in that direction. 

I'll be back tomorrow with an update. Hang loose my friends on Oahu! And get ready... just in case! 
Toodle pip,

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.