forecast examinations--mathematical

[ncweatherwizard]

This is not a method that I use to make a forecast; however, it can sometimes be helpful in deducing particularly where a storm won't go beyond the forecast period. Let's assume the worst situation first (and assuming that the NHC forecast is exactly correct; I doubt they'll be too far right with it), let's extrapolate that point (25.5N 76.5W) at 120 hours.

Plot those points from NHC, and determine a function to roughly represents a curve. I almost always use natural log for these types of situations, because it most accurately reflects the path of a system, and is most able to adjust to curves in the path (exception, earlier cubic would have been needed--but anyway). Assuming I can accuracy to three figures, the function is:

f(x) = 0.0823*e^(-0.0616*x) + 16.3, where x is the longitude as a negative number.

Take the derivative...blah blah...get a slope at 120 hours (or x = -76.5) of -.564--or the change in latitude per degree longitude. Take that slope all the way to the Florida coast, and go to 80.5W, get a latitude of 27.8N--close to Vero Beach. Well we know, that more curve will likely be experienced after 120 hours, and this isn't modeled in our function; therefore, with high confidence in the forecast, you could rule out landfall from Vero Beach southward.

Then take the geographical features--particularly that the coast of FL runs northwestward, and you see the ability to parallel and not hit.

If you do the same with my forecast, at 30.5N the longitude would be 28.9N, or approaching Daytona.

And this is just extrapolating at a point, and not continuing the pattern indicated in the function, so actually these points would actually slip northward, and can be adjusted with later forecasts.

[Anonymous]

Question...Does this take the storm into Gates County North Carolina?

[x-y-no]

Well, your whole premise depends on this assumption: "(and assuming that the NHC forecast is exactly correct; I doubt they'll be too far right with it)".

I, for one, wouldn't mind if your were correct, but I don't see the basis for your confidence that they aren't too far to the right.