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What does Gate-to-Gate Mean?
Posted: Sat May 28, 2011 10:11 pm
by Cyclenall
In terms of tornadoes, when people state during when a tornado is on the ground that a particular supercell TOR signature has (for example) 145 knots gate-to-gate, what does that mean?
Re: What does Gate-to-Gate Mean?
Posted: Sun May 29, 2011 1:44 am
by RL3AO
If the radar shows velocities of +75 and right next to it -70, its said to have 145 g2g shear.
Re: What does Gate-to-Gate Mean?
Posted: Tue May 31, 2011 1:23 am
by Cyclenall
RL3AO wrote:If the radar shows velocities of +75 and right next to it -70, its said to have 145 g2g shear.
That explains how the number is derived, but if by velocity you mean wind speed how can you have -70? Wind shear is the difference of wind speeds in different levels of the atmosphere so its not referring to the intensity of the vortex (tornado) but an atmospheric value?
Re: What does Gate-to-Gate Mean?
Posted: Tue May 31, 2011 7:55 am
by RL3AO
The greens are heading towards the radar and have a negative number. The reds are moving away from the radar and have a positive number. The tornado is circled (one of the EF4s from Oklahoma on May 25).
You can see winds moving (looking at the scale on the left) about 105kts one direction and 105kts the other direction right next to it. That would be 210kt gate to gate shear.
Posted: Tue May 31, 2011 8:02 am
by brunota2003
They do positive and negative to help separate which direction the winds are heading (relative to the radar)
Re: What does Gate-to-Gate Mean?
Posted: Tue May 31, 2011 10:32 pm
by Cyclenall
Thank you both, I now have a complete understanding of what it is. It doesn't necessarily mean the intensity of the main vortex but it "probably" is in a sense. Any word on who and when the jargon expression "gtg" was coined?
RL3AO wrote:The greens are heading towards the radar and have a negative number. The reds are moving away from the radar and have a positive number. The tornado is circled (one of the EF4s from Oklahoma on May 25)
Two things: If what is circled is the tornado, I thought the pink triangle was the signature? And it was May 24 when Oklahoma got some.
Re: What does Gate-to-Gate Mean?
Posted: Tue May 31, 2011 10:43 pm
by RL3AO
Cyclenall wrote: Two things: If what is circled is the tornado, I thought the pink triangle was the signature? And it was May 24 when Oklahoma got some.
It probably hadn't updated since the previous scan. Also I just realized the arrows should be flipped since we're not in the southern hemisphere.
Re: What does Gate-to-Gate Mean?
Posted: Wed Jun 01, 2011 10:37 am
by thetruesms
RL3AO wrote:Cyclenall wrote: Two things: If what is circled is the tornado, I thought the pink triangle was the signature? And it was May 24 when Oklahoma got some.
It probably hadn't updated since the previous scan. Also I just realized the arrows should be flipped since we're not in the southern hemisphere.
Yes, the arrows should be flipped, but it has nothing to do with what hemisphere we're in. Tornadoes are too small and too short-lived to see significant influence from the Coriolis effect. There can be both cyclonic and anti-cyclone tornadoes in the northern hemisphere.