Ophelia another storm that makes me question!!!!!

[oneness]

One of the best examples of differential friction occured with Isidore when it would not leave the Yucatan.

I'm not a met, so maybe one with more expertise could weigh-in. This is my layman's understanding:

The wind over the water accelerates (highest winds are almost always there), then when it hits land it deccelerates, which causes differential friction. The net effect is for the storm to pull itself against the coast.

If the land mass is to the left, the storm pulls left (like Isidore); if it's to the right, the storm will tug right (like Charley).

The more intense the storm is, the higher the topography is, the greater the effect.

If so, the question is, is there a viable pressure coupling or feed-back mechanism which could thus affect the rest of that particular massive storm’s rotational energy levels which are far greater than the differential energy?

[jasons2k]

One of the best examples of differential friction occured with Isidore when it would not leave the Yucatan.

I'm not a met, so maybe one with more expertise could weigh-in. This is my layman's understanding:

The wind over the water accelerates (highest winds are almost always there), then when it hits land it deccelerates, which causes differential friction. The net effect is for the storm to pull itself against the coast.

If the land mass is to the left, the storm pulls left (like Isidore); if it's to the right, the storm will tug right (like Charley).

The more intense the storm is, the higher the topography is, the greater the effect.

If so, the question is, is there a viable pressure coupling or feed-back mechanism which could thus affect the rest of that particular massive storm’s rotational energy levels which are far greater than the differential energy?

I can't answer that. I need to look in AccuWx's archives and see if I can find JB's write-up on this topic. When Isidore was at the Yucatan, he said that the storm would hug the coast, actually pull itself WSW, and essentially rip itself to shreds until the windspeeds were low enough for the storm to be 'released' back over the water. None of the models indicated this movement ahead of time, and sure enough, that's what happened.

I'll see if I can find it, he explained the physics behind it much better than I ever could.

[oneness]

just uploaded pics of some of the damage from ophelia in my area (morehead city, atlantic beach, salter path)...

http://www.digital-ink-graphics.net/ophelia/

lot of damage for category 1, but the wind lasted FOREVER it seemed

~orion

Great photos. I'm always agast when I see modern buildings within areas regularly visited by tropical cyclones using pine as a structural material, in the roof of all places!

Is that really allowed under local building codes?

[oneness]

One of the best examples of differential friction occured with Isidore when it would not leave the Yucatan.

I'm not a met, so maybe one with more expertise could weigh-in. This is my layman's understanding:

The wind over the water accelerates (highest winds are almost always there), then when it hits land it deccelerates, which causes differential friction. The net effect is for the storm to pull itself against the coast.

If the land mass is to the left, the storm pulls left (like Isidore); if it's to the right, the storm will tug right (like Charley).

The more intense the storm is, the higher the topography is, the greater the effect.

If so, the question is, is there a viable pressure coupling or feed-back mechanism which could thus affect the rest of that particular massive storm’s rotational energy levels which are far greater than the differential energy?

I can't answer that. I need to look in AccuWx's archives and see if I can find JB's write-up on this topic. When Isidore was at the Yucatan, he said that the storm would hug the coast, actually pull itself WSW, and essentially rip itself to shreds until the windspeeds were low enough for the storm to be 'released' back over the water. None of the models indicated this movement ahead of time, and sure enough, that's what happened.

I'll see if I can find it, he explained the physics behind it much better than I ever could.

Thanks, would like to read it.

[Robert]

just uploaded pics of some of the damage from ophelia in my area (morehead city, atlantic beach, salter path)...

http://www.digital-ink-graphics.net/ophelia/

lot of damage for category 1, but the wind lasted FOREVER it seemed

~orion

Great photos. I'm always agast when I see modern buildings within areas regularly visited by tropical cyclones using pine as a structural material, in the roof of all places!

Is that really allowed under local building codes?

Great pictures, lots of places I recognize.

And about building codes, yes, pine is fine. I built a house on the inter coastal waterway last year (finished last June). As far as I can tell we overbuilt most of it (built it beyond code). Exmple we used one thickness more then was required on all the plywood (roof and walls). Our walls are 2x6 with threaded steel rods from the top plates on the walls all the way down through the walls (bolted together) and then into J/hooks into the block foundation (I think code requires these on corners, we added them every 6 feet around the house). Hurricane clips are required. The only thing we did not do was increase the size of the roof trusses. Those are just 2x4's. The building inspector was very strict about how the trusses were joined together. The plans called for one 2x4 on the center upright all the way down, with the ends braced with additional 2x4's. We ran ones down each side (on the diaganals), plus braced on the ends much more then that was called for. However, when he came out for the inspection he failed us because we modified the plans (to what we through we be stronger). Because we had not put on the ones that were not required, but had not put the one that was, we did not pass.

My thought when I was building the house is that there is a cost/ benefit relationship. According to our plans (which were approved by the local building inspector) our house should still be standing if we get a Cat 3 hurricane (all things being equal, no trees falling on it or anything like that). You can (I think) build a house that will withstand a stronger hurricanes, but the building costs go up. There is a point, in most peoples budget where you say enough is enough.

Robert

[cancunkid]

My sister has always claimed hurricanes prefer water. She says that is why the Georgia coast is not hit as often as say the North Carolina coast. It just doesn't stick itself out there to get hit! I don't know if it is true but I have to say GA doesn't seem to get a direct hit near as often as some others.

[coriolis]

I've also wondered if gyroscopic procession - the effect that makes a top wobble slowly, affects hurricanes. I have a gut feeling that it only applies to rigid bodies, though. Need to do some research on that.....

Wouldn't that just create delamination and turbulence?

I would imagine, yes. That effect probably does not apply to hurricanes. Sometimes it's easy to envision hurricanes as objects, while they are really patterns of air flow.

[oneness]

I've also wondered if gyroscopic procession - the effect that makes a top wobble slowly, affects hurricanes. I have a gut feeling that it only applies to rigid bodies, though. Need to do some research on that.....

Wouldn't that just create delamination and turbulence?

I would imagine, yes. That effect probably does not apply to hurricanes. Sometimes it's easy to envision hurricanes as objects, while they are really patterns of air flow.

Yeah, it's a bit of a tricky one as it is not entirely clear-cut. The atmosphere basically behaves like a fluid and pressure waves in the fluid may allow a feedback 'response' to propagate through the lower circulation, well, to some extent.

I just kind of suspect that in the battle of the relative energies of the overall rotation verses the opposing frictional lumps and bumps creating a turbulent boundary layer above the land surface, that the circulation’s movement is not going to be affected all that much.

Having said that though, if the steering forces were weak to almost nothing then maybe a very small effect is enough to make a significant difference? Cyclones do dissipate their energy via friction with land and resistance (accelerations) from other air masses … so … maybe a land mass should cause a storm to torsion to some extent if the friction was differentially distributed.

Not entirely sure, but it sounds like I may have just changed my mind.

[oneness]

just uploaded pics of some of the damage from ophelia in my area (morehead city, atlantic beach, salter path)...

http://www.digital-ink-graphics.net/ophelia/

lot of damage for category 1, but the wind lasted FOREVER it seemed

~orion

Great photos. I'm always agast when I see modern buildings within areas regularly visited by tropical cyclones using pine as a structural material, in the roof of all places!

Is that really allowed under local building codes?

Great pictures, lots of places I recognize.

And about building codes, yes, pine is fine. I built a house on the inter coastal waterway last year (finished last June). As far as I can tell we overbuilt most of it (built it beyond code). Exmple we used one thickness more then was required on all the plywood (roof and walls). Our walls are 2x6 with threaded steel rods from the top plates on the walls all the way down through the walls (bolted together) and then into J/hooks into the block foundation (I think code requires these on corners, we added them every 6 feet around the house). Hurricane clips are required. The only thing we did not do was increase the size of the roof trusses. Those are just 2x4's. The building inspector was very strict about how the trusses were joined together. The plans called for one 2x4 on the center upright all the way down, with the ends braced with additional 2x4's. We ran ones down each side (on the diaganals), plus braced on the ends much more then that was called for. However, when he came out for the inspection he failed us because we modified the plans (to what we through we be stronger). Because we had not put on the ones that were not required, but had not put the one that was, we did not pass.

My thought when I was building the house is that there is a cost/ benefit relationship. According to our plans (which were approved by the local building inspector) our house should still be standing if we get a Cat 3 hurricane (all things being equal, no trees falling on it or anything like that). You can (I think) build a house that will withstand a stronger hurricanes, but the building costs go up. There is a point, in most peoples budget where you say enough is enough.

Robert

Ah, very interesting. We are not allowed to use pine in any structural application. It can be used for non-structural walls and panels, but definitely not in the roof. Hardwood or steel for the roof structures. Usually each truss is bolted through two 6 mm steel plates embedded within reinforced concrete wall capping in cinder-block structural walls, or else, into steel or hardwood structural walls.

Lots of strapping and cross-bracing thread is used, of course. No one uses a shingle roof. All are either ribbed sheet steel or heavy cyclone rated tiles. An interesting difference here is that no one shutters their windows or doors. The reality is that the windows usually don't break but if a storm gets that strong that it breaks the windows, then it won't make much difference either way, because everything is going to get wet and wrecked regardless. So you pack up and stow everything in the interior rooms and make your sheltering place away from exposed walls and windows.

And yes, I see neighbours applying the classic masking-tape ‘X’ to their windows. If you point-out that the tape is weak, made of paper and adhesive film, they still remain sure the tape will make a difference. It’s a bit scary to see the lack of understanding in most of the new people in my area. It seems people learn the hard way about cyclones, because there is no way to get across what one can get like.

Hope you guys get things back together quickly in NC.

[Recurve]

Trop cyclones do reach high, but that's the top of the chimney. The inflow and high winds are also all the way down at the surface and the body of the storm does get land effects.

Gyroscopic procession -- sure, why not that kind of force too.

The circulation might be totally different, but I've heard about tornadoes following topography, running through river valleys and not up steeper land.

Anthropomorphizing a wee bit, you just know that warm-water-driven cyclones have an aversion to land.

[ANVANA]

Hell, why not sunspots?

[shaggy]

i am impressed and surprised that other people had thought this out like i have and i see there are alot of ideas/theories on this.Wish there were some better tools of research to try and get a better idea of what is really happening when this phenom occurs!

[Windy]

Just a shot in the dark, but wind speeds slow through friction as they move over land. Lower winds = higher SLP.

[shaggy]

I find the theory of lower winds = higher pressure pretty interesting because one other thing almost all storms that dance along coastal areas have in common is the slow speed as the storms approach the coast.It makes since considering that storms follow the path of least resistance.