?? on Track Error vs. Intensity Error

[Ixolib]

In reference to this piece from Thursday's 5pm advisory...

EXTENDED OUTLOOK. NOTE...ERRORS FOR TRACK HAVE AVERAGED NEAR 250 NM ON DAY 4 AND 325 NM ON DAY 5...AND FOR INTENSITY NEAR 20 KT EACH DAY.

...isn't this saying that the track error is greater than the intensity error? In my observation, I always thought the track was easier to pin down than the intensity??

What's the deal with that. Are they saying their error in track has actually averaged 325NM five days out, yet the intensity forecast has only varied by 20KT???

[wjs3]

I think the track error is a cone, BTW--so 325 miles in either direction.

In the short term, especially, track is not as hard as intensity, as I understand it. There are about a million (it seems) models that will give you track, but I believe the GFDL and the SHIPS are the only two that do intensity. And they can be way, way, way far apart. Checke earlier threads, but I think SHIPS called this one about right, but the GFDL was calling for 118kts at landfall (?!).

I think that in the short term, track is a lot more accurate than intensity, but in the long term, either is pretty weak.

That make sense? Anyone else?

[caneflyer]

You can't compare different physical quantities and say that one is larger than the other. Track error is measured in units of length (n mi) and intensity error in units of speed (n mi/hr, or kt). Comparing the two is like saying that 20 minutes is larger than 5 feet!

Yes, they are saying what the average 5 day errors are for track and intensity. One thing to keep in mind is that intensity is a bounded quantity, since the actual intensity is pretty much bounded to be between 25 kt and, say, 150 kt. This limits the size of the intensity error. On the other hand, it is possible to have a track error of over 1000 nmi, particularly in recurvature situations. Yet, think of all the fuss that people make when a category 1 is forecast and you get a category 3. Such an error could be as small as 20 kt (80 kt vs 100 kt).

[Jim Cantore]

the LBAR was off by like 800 miles

[Ixolib]

You can't compare different physical quantities and say that one is larger than the other. Track error is measured in units of length (n mi) and intensity error in units of speed (n mi/hr, or kt). Comparing the two is like saying that 20 minutes is larger than 5 feet!

Yes, they are saying what the average 5 day errors are for track and intensity. One thing to keep in mind is that intensity is a bounded quantity, since the actual intensity is pretty much bounded to be between 25 kt and, say, 150 kt. This limits the size of the intensity error. On the other hand, it is possible to have a track error of over 1000 nmi, particularly in recurvature situations. Yet, think of all the fuss that people make when a category 1 is forecast and you get a category 3. Such an error could be as small as 20 kt (80 kt vs 100 kt).

Very good points... Thanks.