Friday, September 01, 2017

A note about Harvey, Hurricane Irma, and Tropical Storm Lidia: August 31, Update A

A note about Harvey
The fallout from Harvey continues in Houston and surrounding areas. Although the water is receding, the residents are going to need a lot of help! From one of my amazingly intrepid on-the-ground reporters (from a couple of notes, merged), Fiona L. (a big and special thank you for the updates throughout the storm too – so glad you are ok!):

“We are doing well. Our danger is over. The sun is out and I got my first good nights sleep since last Thursday. The water in our area has receded incredibly quickly and now the horrific job of cleaning out the flooded houses begins. I made my first venture out in the car today, as the grocery store reopened. The shelves are very depleted but the roads are clearing so I am sure supplies will be getting in soon. I have 3 local grocery stores. The H-E-B and Randal’s are flooded. The Kroger opened back up on Thursday. I was hoping to restock on fresh produce. These were the dairy shelves. Produce, meat and ice cream was much the same! 

Seeing the hundreds of volunteers and friends helping people load up the sidewalks with sodden belongings and dry wall, not 5 mins from our house, is horrific. The problem in this climate is how quickly the mold sets in.”

So, that takes me to the question I left hanging earlier in the week: Why didn’t people evacuate? This is a very complicated discussion, but it essentially boils down to the critical importance and relevance of science and technology in our modern world (not that I’m biased at all! ;-)) and the sheer number of people that need to be evacuated.

There are at least four issues:
1.     To evacuate an entire city like Houston safely with a population of over 6.5 million people would take a very long time. Easily over a week (have you been to Houston during rush hour?). There have been countless instances where more people died in trying to evacuate ahead of a major storm. For example, in the case of Hurricane Charley in Florida in 2004, people evacuated inland to the Kissimmee/Orlando area only to find that the storm had shifted track slightly and went to there instead of passing by. Houston has been burned on this before too – prior to Hurricane Rita making landfall in 2005, tens of thousands of people tried to evacuate resulting in a massive traffic jam that lasted long enough for the storm to reach them, out in the open. I think over 100 people died. Evacuation is not as easy to do as it is to say.

2.     We would need to know exactly what the impact of a storm would be about 1.5-2 weeks ahead of time so everyone could pack up and leave in an orderly manner (including hospital patients, the elderly and young, pets etc.) and not get caught in bands of stormy weather. Our understanding of storms and the technology we have means we have an idea about 2-3 days ahead of time, and even then, it’s just an estimate of intensity – the intensity forecast is not great, even at 1-2 days yet. Let alone the 1-2 week needed. We need more scientific study to better understand intensity, and we need more technology to (a) get the data for that understanding, and (b) implement that understanding into a forecast with enough lead time to undertake a massive evacuation like this.

3.     We would also need a place to evacuate all those people to – somewhere with extra hospital beds in other cities, animal shelters etc. Somewhere that could accommodate that many people (plus all the supplies 6.5 million people would need) for a week (or weeks depending on the nature of the storm).

4.     In this case, Harvey didn’t only impact Houston… it impacted the surrounding area – hundreds of miles! We would need to know the impact for hundreds of miles and everyone, including the people in neighbouring counties and towns would also need to evacuate.  

Also, here's a quick and interesting read from a Houstonian on a number of other issues (thanks Fiona L. for sending this too).

That’s it for now about Harvey, and as the sun comes out and the recuperation continues after a very long and horrible 7 days, I think people may need a little smile so the last thing to say is…
(credit: the internet - thanks Ben A. for sending)

Hurricane Irma
Ok, so a really quick analysis on this big beauty. I really think she was a cat 1 storm 24 hours ago although the NHC had her as TS. I am not hugely surprised that she continued to grow because her structure was already well developed throughout the troposphere, and I would say she is now a strong cat 2 or very weak cat 3 storm (which is what the NHC think too). If she was a cat 1, then this is not unusual in this timeframe. So, as the Hitchhikers Guide to the Galaxy says, “Don’t Panic” (much, yet).

She is currently at 17.8N, 35.6W heading WNW at 12mph. Central pressure is 967mb, and officially her estimated wind speed is 115mph which makes her a weak cat 3 (cat 3 range: 111 – 129mph). It is estimated – there are no in situ (meaning in the storm) measurements because she is too far out to fly a plane into to gather the data (this is why we need better technology!!) so they have to estimate her intensity from satellites – it is somewhat subjective.

The reason I think she is a cat 2 (range: 96-110mph)/weak cat 3 is because she has an eye, and it is fluctuating as we see in cat 2/cat 3 storms:
Normally I would not look at the infrared for the eye because it is a little misleading with regard to intensity; the visible image would give a better indication of storm strength, but I got to the imagery too late in the day and it is night already. I'll grab it earlier tomorrow if I can! But a strong cat 3 or a cat 4 would have a more robust eye.

Her circulation is still strong all the way through the troposphere, and there isn’t much to stop her from growing some more, so I wouldn’t be surprised if she became a cat 4 storm.

That takes us to the track, which hasn’t changed much from yesterday’s forecast initially, which is that she will head a little to the south:
The difference is that it looks like she will curve to the north in about 5 days. This is too far out to say with any certainty (remember, she can go anywhere in that white cone - it's not just the center that is important). So, if I were on any of the Windward or Leeward Caribbean Islands, I would prepare for a major storm as we don’t know quite what her path will be. There is a case for her to continue moving to the south but currently also another scenario where she does turn to the north.

Tropical Storm Lidia
Although my intrepid-on-the-ground-reporter didn’t actually get to Baja because the flights were cancelled, I’ll just add a quick note on this. Lidia is a mid-sized to strong Tropical Storm (although I think she may be a strong TS/weak cat 1), but her convection is a lot stronger than her structure, so there is thunderstormy weather over Baja at the moment.

As I suspect I’ll have my spare time sucked up with Irma over the next week, I am going to stop updating on Lidia unless there is someone reading this out there!

Ciao for now!

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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. 


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