Shane Young
EF1
Gotta think it was noise or scale issues or such. Do you have an image of what you were looking at?
10/10/2018 - Hurricane Michael
- Thread starter Warren Faidley
- Start date
rdale
EF5
Always use spectrum width when analyzing velocity data to judge specific pixel reliability.
David Cox
Enthusiast
I didn't but I should of. I was going back and forth between Eglin and Moody (Tallahassee was down) It was a couple of pixels in a sea of green on the upper right of the eye wall before it came on shore. They were gone on the next pass. The green pixels read some very high numbers (173 to a max of 183 mph as crossed Mexico Beach from about 12:50 to 13:15 EDT at 3K' to 4K'), but they seem reasonable considering the strength of the storm. I was using Radarscope Super-Res Velocity and the altitude came from the screen measurement from Eglin radar. I'll remember to screen shot in the future so there is something more concrete to discuss. Thanks..
David Cox
Enthusiast
Thanks for the info. It will really help when looking at thunderstorms where I am (NE FL).
rdale
EF5
I noticed on SN Doug Keisling was hunkered down in Mexico Beach yesterday. I tracked down his footage of the aftermath. It looks like the city was torn apart from stem to stern except a few well built buildings that are still standing.
Warren Faidley
Supporter
Really difficult and extremely dangerous to shot in those unprotected areas with 100+ mph winds. Gulf surge is always hard to predict with any accuracy, especially if you change your position at the last moment. Michael was moving and intensified too fast to build a super-surge. One of the most disturbing surge moments I've had was not with a massive surge, but the day before Hurricane Katrina when increasing waves nearly stranded me on a deserted coastal highway. You know you are going to get a 20+ foot storm surge when it starts flooding the day before the big event like with the 1900's storm, Camille and Katrina.
Jake Orosi
EF4
I'm not saying there's any particularly safe place to be driving in a monster like that; but surely choosing to drive along the beachfront road while the eyewall was making landfall was not a moment of brilliance.
Is there any information about what happened to those two individuals? They abandoned their vehicle in the height of the storm with debris and storm surge washing against them. I really hope they made it to some kind of shelter.
Dan Robinson
EF5
From what I understand, everyone is safe and accounted for. There are reports of at least 3 chaser vehicles lost in storm surge, and 1 unconfirmed lost or heavily damaged from a structure's roof or wall collapsing on them. That last one is a secondhand report, so I do not know who it is nor the details.
Even with preparation and knowledge of what was coming, even I was caught off guard by the actual intensity of the eyewall. I have chased two Category 3 landfalls (Rita and Ivan) and this wasn't just "one notch higher" than those.
I lingered a few minutes too long several blocks east of my parking garage shelter, and my car was constantly being pelted with debris. Storage containers were going airborne. Structures don't provide much shelter, as most of them lost roofs or part of walls which collapse on the downwind side of the structure. Large rooftop HVAC units also were being blown off of buildings and crashing to the street below. Like this at a big church downtown - imagine someone sheltering from the wind there:
Even with preparation and knowledge of what was coming, even I was caught off guard by the actual intensity of the eyewall. I have chased two Category 3 landfalls (Rita and Ivan) and this wasn't just "one notch higher" than those.
I lingered a few minutes too long several blocks east of my parking garage shelter, and my car was constantly being pelted with debris. Storage containers were going airborne. Structures don't provide much shelter, as most of them lost roofs or part of walls which collapse on the downwind side of the structure. Large rooftop HVAC units also were being blown off of buildings and crashing to the street below. Like this at a big church downtown - imagine someone sheltering from the wind there:
Warren Faidley
Supporter
I hate to say it, but I honestly believe we are at the same point in hurricane chasing as we were with storm / tornado chasing before the first fatalities. People are taking increasingly stupid risks to up each other during violent hurricanes. It's just not worth your life for a clip that is already old news 24 hours later.
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Dan Robinson
EF5
So, we have a little bit of an El Reno-esque controversy brewing on Michael's intensity. I'm not as well versed in the nuances of hurricane ratings as I am with tornadoes, so I've been trying to keep up with the discussion between the more "in the knows" about whether or not Michael will be upgraded to Category 5 status in NHC's post-season analysis. Here is what I've been gleaning so far:
Arguments in favor:
- The worst of the observed damage is consistent with Cat 5 winds
- Hurricane Hunter aircraft SFMR instrumentation measured 138kts (158mph) in the *southwest* quadrant of the eyewall during landfall, that's exceeding the Cat 5 threshold on the *weaker* side of the eyewall.
- The storm's satellite/radar presentations (Dvorak) strongly suggest a strengthening Cat 5 at landfall, even post-landfall intensification is noted
- Chaser/research group pressure readings suggest a minimum at or below 918mb at landfall, lower than the official reading.
- Since the one "solid" recon measurement of 135kt (155mph) is just below the threshold, it is highly likely that some other part of the storm exceeded this.
Arguments against:
- SFMR readings can be contaminated by two factors: 1.) "shoaling", which is breaking waves on the ocean surface due to shallow water, and 2.) heavy precipitation rates. Either of those can artificially increase the SFMR readings, and if it is found that either/both of those were present, the 138kt reading must be disqualified as a factor in the final analysis.
- Satellite/radar presentations are not considered in official ratings.
- Ratings are rounded to the nearest 5kt, so the evidence will need to show at least 137.5kts before the storm will be reclassified at 140kts (160mph).
- In the modern era, most of the relevant data used for ratings is available to the NHC in real-time. In other words, it is rare that some rating-changing factor is missed by the official evaluation at the time of landfall. It's not impossible for something extraneous to surface later, but the bar is very high to overturn the operational rating.
Relevant Twitter thread:
https://twitter.com/JustonStrmRider/status/1050783750932566019
Arguments in favor:
- The worst of the observed damage is consistent with Cat 5 winds
- Hurricane Hunter aircraft SFMR instrumentation measured 138kts (158mph) in the *southwest* quadrant of the eyewall during landfall, that's exceeding the Cat 5 threshold on the *weaker* side of the eyewall.
- The storm's satellite/radar presentations (Dvorak) strongly suggest a strengthening Cat 5 at landfall, even post-landfall intensification is noted
- Chaser/research group pressure readings suggest a minimum at or below 918mb at landfall, lower than the official reading.
- Since the one "solid" recon measurement of 135kt (155mph) is just below the threshold, it is highly likely that some other part of the storm exceeded this.
Arguments against:
- SFMR readings can be contaminated by two factors: 1.) "shoaling", which is breaking waves on the ocean surface due to shallow water, and 2.) heavy precipitation rates. Either of those can artificially increase the SFMR readings, and if it is found that either/both of those were present, the 138kt reading must be disqualified as a factor in the final analysis.
- Satellite/radar presentations are not considered in official ratings.
- Ratings are rounded to the nearest 5kt, so the evidence will need to show at least 137.5kts before the storm will be reclassified at 140kts (160mph).
- In the modern era, most of the relevant data used for ratings is available to the NHC in real-time. In other words, it is rare that some rating-changing factor is missed by the official evaluation at the time of landfall. It's not impossible for something extraneous to surface later, but the bar is very high to overturn the operational rating.
Relevant Twitter thread:
https://twitter.com/JustonStrmRider/status/1050783750932566019
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rdale
EF5
I don’t think the ASOS units have been interrogated... I’m under the impression that they still record data as long as they are powered - but obviously unable to transmit that out.
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Sent from my iPad using Tapatalk Pro
What is the source of these points? I have not heard of anything like this...anywhere.
Dan Robinson
EF5
MClarkson
EF5
This storm was well sampled by the eglin radar and doppler velocities were consistently in the high end cat 4 range during the landfall with winds ~4000-6000 feet up of about 160kt. Following a standard flight level reduction this places surface winds in the ~130kt range.
There were isolated occurrences of stronger pixels, so brief cat 5 winds could have occurred. I would personally call it a 135kt cat 4. But its close enough that I don't have a very strong opinion... measurement error could easily cross the threshold between 4/5 in this case.
Interestingly the traditionally much weaker left side of this storm was only about 5kt weaker than the right side. Stronger convection in the left eyewall looks like it almost overcame its geometry.
There were isolated occurrences of stronger pixels, so brief cat 5 winds could have occurred. I would personally call it a 135kt cat 4. But its close enough that I don't have a very strong opinion... measurement error could easily cross the threshold between 4/5 in this case.
Interestingly the traditionally much weaker left side of this storm was only about 5kt weaker than the right side. Stronger convection in the left eyewall looks like it almost overcame its geometry.
