Max sustained winds already adjusted for forward speed?

[NC George]

I thought the speed reported was already adjusted for forward speed. In other words when they report 125 mph winds that's the wind you can expect in the NE quad. If the storm is moving forward at 12.5 mph, wouldn't you expect to find 100 mph winds on the other (SW) side? Please clarify, as I think they confuse me every year on this.

[mdlemin]

Sounds like someone was playing pranks. Just wait for the next NHC update.

[Wthrman13]

I thought the speed reported was already adjusted for forward speed. In other words when they report 125 mph winds that's the wind you can expect in the NE quad. If the storm is moving forward at 12.5 mph, wouldn't you expect to find 100 mph winds on the other (SW) side? Please clarify, as I think they confuse me every year on this.

I replied to this in the original thread. The winds reported are always actual, ground-relative wind speeds. There is no adjustment to forward speed. Because of this, the winds on the right flank of the storm will generally be stronger than on the left. It's no more complicated than that. Hope that clarifies things.

[NC George]

No, this is a serious, general question, not specific to this hurricane, but all hurricanes.

As I understand it, there are two components to the windspeed in the hurricane: the wind speed about the circulation and the forward speed of the storm. Because on the right side (relative to forward direction) of the hurricane the wind speed and the forward speed are additive, and thus the measured speed will be the sum of the forward speed and the circulation speed; and on the left side of the hurricane the forces will be subtractive, and thus the measured speed will be the circulation wind speed minus the forward speed. The net effect of this is the windspeed on the right side will be higher than the left side by a factor of two times the forward speed.

Now I'm pretty sure everything I've just said is correct. The question is, when the NHC quotes the max sustained speed, do they quote the combined windspeed seen only of the left side of the storm, or do they report the circulation wind speed. I say they report the combined windspeed containing the forward motion component and the circulation windpeed component.

[Wthrman13]

No, this is a serious, general question, not specific to this hurricane, but all hurricanes.

As I understand it, there are two components to the windspeed in the hurricane: the wind speed about the circulation and the forward speed of the storm. Because on the right side (relative to forward direction) of the hurricane the wind speed and the forward speed are additive, and thus the measured speed will be the sum of the forward speed and the circulation speed; and on the left side of the hurricane the forces will be subtractive, and thus the measured speed will be the circulation wind speed minus the forward speed. The net effect of this is the windspeed on the right side will be higher than the left side by a factor of two times the forward speed.

Now I'm pretty sure everything I've just said is correct. The question is, when the NHC quotes the max sustained speed, do they quote the combined windspeed seen only of the left side of the storm, or do they report the circulation wind speed. I say they report the combined windspeed containing the forward motion component and the circulation windpeed component.

Yes, exactly, which is exactly what I said in my previous post

It's the ACTUAL wind speed measured relative to the ground

[NC George]

I replied to this in the original thread. The winds reported are always actual, ground-relative wind speeds. There is no adjustment to forward speed. Because of this, the winds on the right flank of the storm will generally be stronger than on the left. It's no more complicated than that. Hope that clarifies things.

Then either you misunderstood me in the original RECON thread or you just contradicted yourself. If they are reporting measured windspeed from the aircraft of 100 mph on the left (SW) side of this particular storm, wouldn't that equate to a windspeed of 128 on the NE (right) quadrent. Which, since I just heard it was upgraded to 135 would make me essentially correct. Not trying to be argumentative, just want to get is straight.

[Wthrman13]

I replied to this in the original thread. The winds reported are always actual, ground-relative wind speeds. There is no adjustment to forward speed. Because of this, the winds on the right flank of the storm will generally be stronger than on the left. It's no more complicated than that. Hope that clarifies things.

Then either you misunderstood me or you just contradicted yourself. If they are reporting measured windspeed from the aircraft of 100 mph on the left (SW) side of this particular storm, wouldn't that equate to a windspeed of 128 on the NE (right) quadrent. Which, since I just heard it was upgraded to 135 would make me essentially correct. Not trying to be argumentative, just want to get is straight.

Ok, let me try this one more time. Sorry if I sound a little frustrated, it's late and I'm going to bed after this

Wherever the aircraft is, it measures the ACTUAL wind speed. No adjustment to forward speed is made. So, let's say it measures 125 mph on the left side, and the hurricane is moving due north at 10 mph. This means that, assuming the hurricane is symmetric about it's center, that the winds on the right side would be on the order of 145 mph. Does that make sense? If another plane were in the right side, it would measure around 145 mph. Both of those would be actual ground-relative wind speeds, but would be higher on the right side because of the addition of the forward motion.

[NC George]

We are both on the same page now. Thanks for your clarification.

[Wthrman13]

We are both on the same page now. Thanks for your clarification.

No problem, sorry for the confusion. It can be tricky.