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Chasing ERNESTO


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josh checked in on FB:

https://www.facebook...151018841584597

It was a small, violent cyclone. Rode it out in a roadside restaurant in Buena Vista, near 18.882N 88.244W, which is W or WNW of Costa Maya. Lowest pressure 975.0 mb at 12:34 am CDT

Josh will probably have to send the barometer to the NHC for calibration or something like that. Quite a feat to record the minimum pressure in a storm and change history a little.

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I'm pretty skeptical...looking at recon this thing has really unwound that tight core and it's doubtful the coc will ever get more than 30 miles away from the coast. Also, although the last advisory lists the speed at 7 mph, the speed between the last 2 recon was must faster than that.

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There are so many thank-yous to give, I don't even know where to start. You guys in this thread have been awesome. Believe it or not, it really helps your morale to know you have your "home crowd" rooting for ya when you're driving alone, at night, in the middle of nowhere . :wub:

Like all chases, this will get a full write-up—but for now, here's the quick 411:

post-19-0-71687100-1344495135_thumb.jpg

I honestly wasn't planning on chasing Ernesto. Scott and I decided I wouldn't. But very early yesterday morning, the storm started to give me vibes—just the look of it on infrared satellite imagery. And I knew I had to chase it.

I packed a bag and rushed to the airport—and then from Cancun rushed down the Yucatan Peninsula to meet Ernesto's tiny but powerful core as it roared ashore in the swampy darkness.

Key points of meteorological interest:

  • Chase Location. I rode out the storm in a roadside restaurant in Buena Vista, near 18.882N 88.244W, which is WNW of Costa Maya/Mahahual.
  • Pressure & Proximity. The lowest pressure of 975.0 mb occurred at 12:34 am CDT, with the winds seeming to peak and coming roughly from the W at that time. I never had a lull. Based on all this, I think I was a mile or two S of the center. Today I noticed that in Limones, approx. 10 mi to the N, the trees were bent the opposite direction—so my theory is that the very small eye passed between the two towns.
  • Dimensions. The cyclone was very small: the winds did not become destructive until about 30 minutes before the center's closest approach. It was about 12 midnight when it suddenly came roaring in, and the worst of it was over within about one hour. The sharp V-shape of the air-pressure trace (recorded with my Kestrel 4500) is the classic barogram signature for a small, intensifying, deep-tropical hurricane. The gradient was extremely sharp: at one point, the pressure was dropping 1 mb every 2 minutes.

Ernesto_Barogram2.png

All of the above analysis is preliminary—I need to look at it all more closely.

Re: video... I shot some, but I don't know how good it is. It was very dark and the conditions were not great. I'll be reviewing the footage over the weekend, and I'm hoping to pull something together that captures the experience.

Big, enormous thanks to the iCyclone team—especially Scott, who deftly maneuvered me into position during those final, hectic hours. He's a total pro. This was a tough chase and it wouldn't have been as successful without Scott, as well as additional assistance from Adam and Steve. :thumbsup:

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There are so many thank-yous to give, I don't even know where to start. You guys in this thread have been awesome. Believe it or not, it really helps your morale to know you have your "home crowd" rooting for ya when you're driving alone, at night, in the middle of nowhere . :wub:

Like all chases, this will get a full write-up—but for now, here's the quick 411:

post-19-0-71687100-1344495135_thumb.jpg

I honestly wasn't planning on chasing Ernesto. Scott and I decided I wouldn't. But very early yesterday morning, the storm started to give me vibes—just the look of it on infrared satellite imagery. And I knew I had to chase it.

I packed a bag and rushed to the airport—and then from Cancun rushed down the Yucatan Peninsula to meet Ernesto's tiny but powerful core as it roared ashore in the swampy darkness.

Key points of meteorological interest:

  • Location. I rode out the storm in a roadside restaurant in Buena Vista, near 18.882N 88.244W, which is WNW of Costa Maya/Mahahual.
  • Pressure & Proximity. The lowest pressure of 975.0 mb occurred at 12:34 am CDT, with the winds seeming to peak and coming roughly from the W at that time. I never had a lull. Based on all this, I think I was a mile or two S of the center. Today I noticed that in Limones, approx. 10 mi to the N, the trees were bent the opposite direction—so my theory is that the very small eye passed between the two towns.
  • Dimensions. The cyclone was very small: the winds did not become destructive until about 30 minutes before the center's closest approach. It was about 12 midnight when it suddenly came roaring in, and the worst of it was over within about one hour. The sharp V-shape of the air-pressure trace (recorded with my Kestrel 4500) is the classic barogram signature for a small, intensifying, deep-tropical hurricane. The gradient was extremely sharp: at one point, the pressure was dropping 1 mb every 2 minutes.

All of the above analysis is preliminary—I need to look at it all more closely.

Re: video... I shot some, but I don't know how good it is. It was very dark and the conditions were not great. I'll be reviewing the footage over the weekend, and I'm hoping to pull something together that captures the experience.

Big, enormous thanks to the iCyclone team—especially Scott, who deftly maneuvered me into position during those final, hectic hours. He's a total pro. This was a tough chase and it wouldn't have been as successful without Scott, as well as additional assistance from Adam and Steve. :thumbsup:

Good stuff Josh... that pressure graph is textbook, and I'm sure the folks at NHC would be more than interested to see that. I'm sure you are planning on sending Landsea or Beven those obs from the storm once you have written up your full report (if you haven't done that already ;) ). In any event, congrats on another successful chase!

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I did a simple gradient wind calculation on your pressure trace, V2 = (dp/dr)*lengthofintegration/density, dr and the length of integration are basically the same if you take the simplest approximation, and I found them by multiplying the speed of the storm at landfall (24 km/hr) by the time (2 hours) for a distance of ~48 km. Density ~1.2 kg/m^3, and dp is ~24 hPa.

In the end this yields a wind speed of 45 m/s (100 mph), which has some semblance of reality despite being so approximated. Caveats that must be taken into account though are that this doesn't account for friction, nor does it account for the fact that you weren't at the very center of the storm. I'm sure a drag term or correction can easily be added though. Also if you did this with every pressure observation you have (which would be easy to do in excel) you would get a more precise result than estimating a single dp/dr for the entire storm like I did. Obviously the pressure drop is steeper towards the center than on the outsides and this changes things than if the pressure drop was linear throughout the storm.

How strong do you think the winds were Josh?

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Congrats Josh. I couldn't be as active posting, but would get back to my phone to occassionally look at how things were going.

It was raining in Tampico, heavily at times, this morning...at least I got something out of Ernesto :P

:weenie:

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I have a bunch of people to thank in this thread, and I'll do that later-- but for tonight, I just wanted to let ya know my chase video is now live!

Hey, it's not beautiful camerawork—the darkness and chaos made it almost impossible to setup a clean shot—but it captures the experience of riding out a direct hit from a small, strengthening hurricane in a roadside restaurant deep in the tropics.

The video starts quietly and it builds as the hurricane approaches. The roaring climax happens just after 12:30 am (note the timestamp), when Ernesto's center passes just a mile or two to the south and we're in the punishing inner north eyewall. Not surprisingly, this is also the time of the lowest pressure (975.0 mb). This radar image below is from that moment—with the red diamond showing my location.

You'll notice in the video that the cyclone doesn't last long—the whole thing comes and goes in less than an hour. It's a swift, hard kick!

I'll post a complete chase account tomorrow. In the meantime, enjoy the video!

post-19-0-26658100-1344829833_thumb.png

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great video Josh! I think you mentioned it before, but it's always sobering to see just how powerful even a "measly" Cat 1 storm is.

Isn't it??

Ernesto really reminded me of how powerful any hurricane is if you get a bull's-eye, direct hit. They might upgrade this to a low-end Cat 2 in seasonal postanalysis, but the bottom line is that even this tiny, non-major hurricane was violent and mean as it passed over us.

Glad you like the video-- thank you.

Great video Josh!

Thanks, Tony! I really appreciate it.

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Isn't it??

Ernesto really reminded me of how powerful any hurricane is if you get a bull's-eye, direct hit. They might upgrade this to a low-end Cat 2 in seasonal postanalysis, but the bottom line is that even this tiny, non-major hurricane was violent and mean as it passed over us.

Great video as always Josh!

I was just about to make the same comment about the power of even a cat 1 or 2 if you're well positioned but I see hm8 beat me to it :P

It kinda reminds me of those videos of Katrina by Mike Theiss taken from S FL while she was still just a cat 1 but nonetheless caused considerable damage.

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