TD 10...Back Again

[gkrangers]

I am not sure if I am asking this in the right place and I am sorry for the ignorant question. How many NM are there between points? Like 74 W and 75 West? Is it the same North? Thanks for any responses.
Debbie

Depends on where the points are relative to the equator.

At the equator, it is the same as latitude: 1° = 60 nm.

However, as you head north or south from the equator, the distance shrinks.

The conversion factor is the cosine of the latitude. For example, for 20° latitude , cos(20) ~= .9397 .9397* 60 = 56.3 . So at 20° latitude 1 ° longitude = 56.3 nm ...

For the tropics, the conversion factor doesn't take much off, so 60 nautical miles is a reasonable approximation if you don't have a calculator or trig table handy. However, as you head further north or south from the equator, the differences become significant.

hope this helps...

Wow... I knew the day that people started using cosine in their post was going to be a strange day indeed.

OK my next question. What is cosine? I tried to look in a weather glossary before I asked and couldn't find it.

Debbie

I see someone didn't make it through Trigonometry in high school.

[Matt-hurricanewatcher]

No I'm not on drugs.

I also you can see that surge of SAL on visible/Sal maps. Once that hits it it will not make it.

[jabber]

I am not sure if I am asking this in the right place and I am sorry for the ignorant question. How many NM are there between points? Like 74 W and 75 West? Is it the same North? Thanks for any responses.
Debbie

Depends on where the points are relative to the equator.

At the equator, it is the same as latitude: 1° = 60 nm.

However, as you head north or south from the equator, the distance shrinks.

The conversion factor is the cosine of the latitude. For example, for 20° latitude , cos(20) ~= .9397 .9397* 60 = 56.3 . So at 20° latitude 1 ° longitude = 56.3 nm ...

For the tropics, the conversion factor doesn't take much off, so 60 nautical miles is a reasonable approximation if you don't have a calculator or trig table handy. However, as you head further north or south from the equator, the differences become significant.

hope this helps...

I just realized it wouldn't be in a weather glossary but it is more of a mathematical term, right?

Debbie

Right google and learn.

[Wnghs2007]

No I'm not on drugs.

I also you can see that surge of SAL on visible/Sal maps. Once that hits it it will not make it.

[elysium]

If the NHC isn't mentioning the SAL, it's for a very good reason, but beyond the scope of this discussion. As for TD 10's satellite presentation, it has scarcely been better than right now. Perhaps I'm taking into account that the shear has lessoned considerably and that while TD 10 may be presenting weak as you say, what is out there in front of it that can dissipate now? It looks pretty good ahead of it now. But my whole point is that when I look at TD 10, perhaps it's that the road ahead of it is so glittering by anyone's interpretation unless you add something in there that isn't in the NHC forecast, or any credible forecast for that matter, that makes TD 10 just appear on satellite imagery to have never looked better.

Actually though, TD 10 looks great no matter how you look at it. What is it about the satellite imagery that doesn't impress you?

I think that we need to shed some additional light on the trough forecasted to be moving off the east coast on around day 5, and how that trough might effect TD 10 forward speed and directional heading. It's pulling teeth out there to get a handle on the trough's progression. We may have to wait until the NHC gets a better handle on this feature before trying to forecast TD 10.

[sweetpea]

Trig? what is trig? LOL just kidding. No I didn't have to take that. In college I was only going for a paralegal degree so I didn't need it there either. Thank God. Math is definitely not my strong point. Thanks for all your help guys.

Debbie

[wzrgirl1]

No I'm not on drugs.

I also you can see that surge of SAL on visible/Sal maps. Once that hits it it will not make it.

Congratulations you get the John Kerry of the Week Badge.

Thing looks great its back to TD 10, now: Its dying, argh! Flip Floppity Flip

remember that when you make political inuendos you insult half of the posters

[BensonTCwatcher]

It's a good thing the NHC does not have to issue advisories based on the average strenght based on posts here. Perhaps a rating like Dvorak, except here a system will go from a wave to cat 5 to back to wave hitting Miami then VA beach and back to Galveston....and that would all happen from the 5p to 11p advisory

[cycloneye]

No I'm not on drugs.

I also you can see that surge of SAL on visible/Sal maps. Once that hits it it will not make it.

Congratulations you get the John Kerry of the Week Badge.

Thing looks great its back to TD 10, now: Its dying, argh! Flip Floppity Flip

Please let's refrain from political remarks.

[clfenwi]

I am not sure if I am asking this in the right place and I am sorry for the ignorant question. How many NM are there between points? Like 74 W and 75 West? Is it the same North? Thanks for any responses.
Debbie

Depends on where the points are relative to the equator.

At the equator, it is the same as latitude: 1° = 60 nm.

However, as you head north or south from the equator, the distance shrinks.

The conversion factor is the cosine of the latitude. For example, for 20° latitude , cos(20) ~= .9397 .9397* 60 = 56.3 . So at 20° latitude 1 ° longitude = 56.3 nm ...

For the tropics, the conversion factor doesn't take much off, so 60 nautical miles is a reasonable approximation if you don't have a calculator or trig table handy. However, as you head further north or south from the equator, the differences become significant.

hope this helps...

Wow... I knew the day that people started using cosine in their post was going to be a strange day indeed.

OK my next question. What is cosine? I tried to look in a weather glossary before I asked and couldn't find it.

I just realized it wouldn't be in a weather glossary but it is more of a mathematical term, right?

Debbie

Yep, it's a math term, from trigonometry, specifically. For this particular purpose, there's no need to go into the gory details.

To find the conversion factor that I mentioned in my original post, go here:

http://www.industrialpress.com/Trig.htm

and go down the first column until you find the latitude you want the conversion factor for. The second column (labeled) is the conversion factor for that latitude. Take that number, multiply it by 60, and you have the number of nautical miles in 1° of longitude at the particular latitude.

Like I said earlier, (and as gkrangers noted) 60 nautical miles is a good approximation, especially for low latitudes (i.e. the Tropics).

However, my father was among other things, a navigator. He would not be happy with me just saying 'oh yeah, it's 60 nautical miles'.

[gkrangers]

If the NHC isn't mentioning the SAL, it's for a very good reason, but beyond the scope of this discussion. As for TD 10's satellite presentation, it has scarcely been better than right now. Perhaps I'm taking into account that the shear has lessoned considerably and that while TD 10 may be presenting weak as you say, what is out there in front of it that can dissipate now? It looks pretty good ahead of it now. But my whole point is that when I look at TD 10, perhaps it's that the road ahead of it is so glittering by anyone's interpretation unless you add something in there that isn't in the NHC forecast, or any credible forecast for that matter, that makes TD 10 just appear on satellite imagery to have never looked better.

Actually though, TD 10 looks great no matter how you look at it. What is it about the satellite imagery that doesn't impress you?

I think that we need to shed some additional light on the trough forecasted to be moving off the east coast on around day 5, and how that trough might effect TD 10 forward speed and directional heading. It's pulling teeth out there to get a handle on the trough's progression. We may have to wait until the NHC gets a better handle on this feature before trying to forecast TD 10.

Well for one, the environment ahead is not "glittering".

And from the 8:05PM EDT TWD, issued by TAFB.

Here is your SAL.

AN ATLANTIC OCEAN TROPICAL WAVE IS ALONG 49W SOUTH OF 19N MOVING
WEST 15 KT. AFRICAN DUST IS NOTED FROM 10N-20N BETWEEN 30W-50W
MOVING W. CONVECTION IS CONFINED TO THE ITCZ.

[Wnghs2007]

No I'm not on drugs.

I also you can see that surge of SAL on visible/Sal maps. Once that hits it it will not make it.

Done

[sweetpea]

LOL about your dad. Thanks cf

Debbie

[storms in NC]

Don't know what you are looking at but 10 L is looking fine as of now. It is the same as it was earlyer this evening

[hurricanetrack]

It sure looks bad now- none of the global models "like" this system very much- it's small, weak and getting beat like a rented car for Spring Break. I actually hope to see this thing dead and buried soon on the TWO. It is getting annoying- let's move on and await the big dogs that we know are coming. These dried up, scrawny low pressure areas are not worth all of this anguish. If we had no Internet, we would not even know it was there. Unless you happened to catch TWC for the 90 second tropical update. But that's a whole other issue.

[gkrangers]

Yeah....I dont't expect strong wording in the TWO tonight. Maybe they'll even throw in a "if it survives".

[Ivanhater]

exactly, steve lyons was just saying to watch the caribbean wave very closely as well as the very strong wave coming off africa tomorrow

[elysium]

TD 10 has never looked better. Appears to be right on track of the NHC's forecast of when to expect more robust regeneration.

The models are also weakening the trough and don't have it digging potently to the south. The SAL is also abating on satellite imagery, but this comes as no surprise as it progersses into richer and richer moisture laden longitudes which are heavier to penetrate. We still have no idea about where TD 10 is going or what it is likely to do until we get a better handle on the trough. Waiting for the 00Z from GFS, but so far nothing yet, and 18Z is too vague to base even a guess upon. The EURO has retrograded the trough over twenty degrees westward. The thing is it is unclear whether the westward component was added in response to the ridging or weakness of the trough since it weakens the trough somewhat in the 00Z but maintains its 18Z position on the ridge. Once the NHC chimes in we should get a better picture of TD 10 response to the trough in whatever form it makes it to the east coast.

[Sanibel]

Can't estimate direction because the spiral is too weak right now.

Sometimes a fading spiral precedes a center relocation...

[hurricanetrack]

While I have no idea how strong the shear really is since I did not look it up on any site- you can see on the colorized IR floater animation that any new pop-corn convection that fires up in what looks like a curved band to the west, gets torn off from SW to NE. Looks a lot like a meteor zipping across the sky. Up goes a thunderstorm tower, and ZIP- there it goes off to the NE. It just looks painful and I cannot believe I am actually pulling for this thing....this is crazy.....no one wishes for the calamity that comes with hurricanes, but we're beating ourselves up over a horrid little scrap of a cyclone.