Ginx snewx Posted September 16, 2011 Share Posted September 16, 2011 Yeah, I would agree with that assessment. The buoy data showed a surprisingly concentrated wind field. (I was kind of surprised, at least.) Josh, a coworker just walked into my office and handed me a book written in 2005 by Cherie Burns. The Great Hurricane of 1938. Never new it existed, very interesting forward. Link to comment Share on other sites More sharing options...
forkyfork Posted September 16, 2011 Share Posted September 16, 2011 A "hurricane" at this latitude, in this state of transition, and with that forward speed is going to have the highest winds well E of the center, so I'm not surprised. i understand that... still, i would have expected to see higher than 25 kt in the western eyewall Link to comment Share on other sites More sharing options...
Ginx snewx Posted September 16, 2011 Share Posted September 16, 2011 i understand that... still, i would have expected to see higher than 25 kt in the western eyewall Yea,I wonder if its wind speeds are suspect, all the buoys on either side were much higher sustained, here is the text data as the center passed overhead. Man I miss quikscat 09 16 12:00 pm WNW 29.1 38.9 - - 29.40 09 16 11:00 am W 3.9 9.7 - - 29.20 09 16 10:00 am ESE 25.3 33.0 - - 29.28 Immediately to the southeast the Laurentian Fan recorded this 09 16 10:00 am NW 40.8 58.3 29.28 09 16 9:00 am SSE 25.3 33.0 29.10 09 16 8:00 am SE 35.0 42.7 29.31 Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 16, 2011 Share Posted September 16, 2011 Wouldn't the wind field spreading away from the center just be part of ET? Link to comment Share on other sites More sharing options...
phil882 Posted September 16, 2011 Share Posted September 16, 2011 That 15-20 knots, does that mean it has -30 knots (or a South wind) West of the center? That doesn't sound quite right. The flow west of the storm is still northerly, but its no longer associated with the system, but with air mass behind the baroclinc zone. Hence the storm has become tangled in the front. Thus when forecasters mention a system has "become absorbed by a front." It means that its no longer has a closed circulation free of temperature gradient, and in this case this is true since the northerly flow behind the storm is associated with the frontal boundary. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 16, 2011 Share Posted September 16, 2011 The flow west of the storm is still northerly, but its no longer associated with the system, but with air mass behind the baroclinc zone. Hence the storm has become tangled in the front. Thus when forecasters mention a system has "become absorbed by a front." It means that its no longer has a closed circulation free of temperature gradient, and in this case this is true since the northerly flow behind the storm is associated with the frontal boundary. It hadn't merged with the frontal zone when it was being accelerated. It was obviously starting to feel the Westerlies, but it wasn't ET yet. When it was moving around 40 knots, and had 70 knot top winds, it had calm winds on the West side? I also think once it did get close to the frontal zone, winds would not mix down well into a stable near surface layer. I'm impressed with gusts to hurricane force even over the East side, considering the temps in Nfdld when they still had South winds, honestly. I just have an issue with the assumption of straight addition/subtraction of the speed of the storm as far as left side/right side wind actions. I just have a suspicion it is an over-simplification. Link to comment Share on other sites More sharing options...
Amped Posted September 16, 2011 Share Posted September 16, 2011 It hadn't merged with the frontal zone when it was being accelerated. It was obviously starting to feel the Westerlies, but it wasn't ET yet. When it was moving around 40 knots, and had 70 knot top winds, it had calm winds on the West side? I also think once it did get close to the frontal zone, winds would not mix down well into a stable near surface layer. I'm impressed with gusts to hurricane force even over the East side, considering the temps in Nfdld when they still had South winds, honestly. I just have an issue with the assumption of straight addition/subtraction of the speed of the storm as far as left side/right side wind actions. I just have a suspicion it is an over-simplification. Yes the storm is accelerating air that is already moving so it moves faster. However Kinetic energy =1/2MV2 This means that adding the same amount of energy to air already moving 100mph won't accelerate it nearly as much as it would air that is stationary. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 17, 2011 Share Posted September 17, 2011 Yes the storm is accelerating air that is already moving so it moves faster. However Kinetic energy =1/2MV2 This means that adding the same amount of energy to air already moving 100mph won't accelerate it nearly as much as it would air that is stationary. That I understand, I just think treating a hurricane as a rotating solid and doing simple addition and subtraction is an oversimplification. And I really think it gets more complicated when the storm is moving at a mean speed of steering while the strength of the winds above the surface isn't a constant. I also have a gut feeling on a storm in the deep tropics, nothing hinky/baroclinic going on, close to due West, the winds 20 miles due East of the center would not be exactly equal to 20 miles due West of the center, which treating the storm as a rotating solid would imply. Link to comment Share on other sites More sharing options...
k*** Posted September 17, 2011 Share Posted September 17, 2011 That I understand, I just think treating a hurricane as a rotating solid and doing simple addition and subtraction is an oversimplification. And I really think it gets more complicated when the storm is moving at a mean speed of steering while the strength of the winds above the surface isn't a constant. I also have a gut feeling on a storm in the deep tropics, nothing hinky/baroclinic going on, close to due West, the winds 20 miles due East of the center would not be exactly equal to 20 miles due West of the center, which treating the storm as a rotating solid would imply. I understand what you are saying and agree that viewing it in such simplistic terms isn't ideal, but...everything is a simplification since the windfield is always already too complex to describe in a complete manner. Even HRD wind plots are gross oversimplifications. IOW, The idea that we can add and subtract forward speed might not be completely accurate but I still think it is a useful heuristic. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 17, 2011 Share Posted September 17, 2011 I understand what you are saying and agree that viewing it in such simplistic terms isn't ideal, but...everything is a simplification since the windfield is always already too complex to describe in a complete manner. Even HRD wind plots are gross oversimplifications. IOW, The idea that we can add and subtract forward speed might not be completely accurate but I still think it is a useful heuristic. That I agree with, there is obvious value to things like 'the strong side' and 'the weaker side' of a landfalling TC, although judging from the direction of most of the downed trres in my hood after the 2008 storm, the supposed weaker side may have been stronger than the strong side. Or maybe trees exposed to wind from one direction and hours of rain are more likely to uproot when the wind shifts. Link to comment Share on other sites More sharing options...
salbers Posted September 17, 2011 Share Posted September 17, 2011 I think adding or subtracting wind speed has more to do with the isallobaric wind rather than the analogy of a solid body moving. Link to comment Share on other sites More sharing options...
Ed Lizard Posted September 17, 2011 Share Posted September 17, 2011 I think adding or subtracting wind speed has more to do with the isallobaric wind rather than the analogy of a solid body moving. I can see isallobaric wind contributing to the right front being the strongest quadrant, but the tack motion on or off is broader than just a quadrant, it is half the storm. Link to comment Share on other sites More sharing options...
salbers Posted September 17, 2011 Share Posted September 17, 2011 I would suggest that farther from the center there is less wind added, consistent with the smaller isallobaric gradient. And to the left of the center the isallobaric field will properly subtract from the wind. It seems to me like it all works out for various locations around the storm. Link to comment Share on other sites More sharing options...
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