5 day Cone

[Rainband]

I just found out recently that the 5 day cone was insisted upon by emergency managers to help make long range plans. It is essentially worthless and causes more panic than good. Ernesto really made this point valid. I tend to agree with the assessment but I want to see what you all think too.

[Stratosphere747]

IMO, it is useless, and if you asked the honest opinion of the NHC forecasters they would be more than happy to get rid of it..

[Bailey1777]

My thoughts would be along the level is there anything in the near future technology wise that will be able to make long range forecasting more accurate so the 5 day cone can be counted on. Are there any synoptic factors out there that we have not tapped yet, or is it timing?

[wsquared77]

I personally don't put any stake in it, especially since it always covers such a wide area...like the ENTIRE state of FL!

[StormTracker]

I think it's purpose is to keep people on their P's & Q's so that they don't get lackadaisical about hurricane season!!! "Better Safe Than Sorry!!!

[Brent]

I like the cone, it's the black line that needs to go.

[StormTracker]

I like the cone, it's the black line that needs to go.

Yeah Brent, that could work!

[Rainband]

I like the cone, it's the black line that needs to go.

Good point but who focuses on that line

[StormTracker]

I like the cone, it's the black line that needs to go.

Good point but who focuses on that line

Everyone accept us!!!

[Brent]

I like the cone, it's the black line that needs to go.

Good point but who focuses on that line

Too many people(mostly not on this board), but I'm even guilty of it sometimes.

[StormTracker]

I like the cone, it's the black line that needs to go.

Good point but who focuses on that line

Everyone accept us!!!

Meaning people like us on forums like this!

[windycity]

The five day cone is a joke, almost a sure thing you wont get hit if your area is in the 5 day outlook. I dont see it going away, people want it!

[cpdaman]

most storms will have less complex steering currents than ernesto, along with better model agreement, in most cases the 5 day cone does more good than harm

there will always be panicky people but thankful more are rational and will make possible preparations. those that live in hurricane prone areas must realize that if they live near the water or in cities like neworleans, and tampa they must get out, and if i was in neworleans i wouldn't trust the levees and i would be out of there for a cat 1, i would go inland in most cities if i was near the water even for a CAT 1. Why some may ask?

water my friends is more dangerous and unpredictable than wind, however that being said if there is a cat 4 or more coming my way i am getting out of florida.

and i understand some people don't have the means to leave as easily , but the governor and mayor's of the respected states should have the awareness and plan in place to get people out, and the gov't better support and aide in doing so

[SouthFLTropics]

I personally don't think that it is worth anything. But it does do two things. One, it does tend to keep the publics attention. Two, it sure generates some really interesting debates here on Storm2k, ie. It's Texas, NO it's Florida, NO it's Nova Scotia. LOL

[brunota2003]

almost? well someone forgot to give my area that memo about the 5 day cone...Isabel, Alex, Bonnie, Charely, Ophelia, and now Ernesto...the one that missed was Irene...so please pass the memo on to my area that when your in the 5 day cone you normally dont get hit...please!!!

[StormTracker]

I personally don't think that it is worth anything. But it does do two things. One, it does tend to keep the publics attention. Two, it sure generates some really interesting debates here on Storm2k, ie. It's Texas, NO it's Florida, NO it's Nova Scotia. LOL

I concur SFLT!!!

[Opal storm]

I like the 5 day cone.I know it changes everyday but I think people would take the storm too lightly or wait to the last minute to prepare if it was just a 3 day forecast.

[Rainband]

I like the 5 day cone.I know it changes everyday but I think people would take the storm too lightly or wait to the last minute to prepare if it was just a 3 day forecast.

after the past two seasons anyone who takes as storm lightly needs to move to montana.

[wxman57]

I don't know how useful the 5-day cone is to the general public, but I can explain how it is generated.

The NHC calculates average track error for each time step out to 120 hours. The data are summarized in the graphic below:

http://www.nhc.noaa.gov/verification/fi ... r_dist.gif

Beginning in 2006, there has been a change from using the average error over the past 10 years to the past 5 years. This was done because of recent improvents in model projections and significant increases in track accuracy.

The cone size at each time step is determined by drawing a vertical line through teh 60% value in the graphic above. This means that over the past 5 years, the storm tracked within the cone 60% of the time. It also means the reverse - the track was outside the cone 40% of the time.

Problems with the cone:

1. The cone is always the same, no matter what the confidence in the forecast track.

But there are times when average track error is much less than normal - like a strong hurricane moving at a fast speed. For those hurricanes, the average error is likely a lot lower so the cone should be reduced. The reverse is true for newly-formed depressions or stalled storms. One solution would be to tie the cone size to forecast confidence based on the physical characteristics of the current storm (intensity and speed of movement).

2. 5-year track error is assumed to be perpendicular to the track, which can lead to values that are too high in the graphic above.

Consider a storm where the forecast is off 800 miles at the 120-hr point but that error is exactly along the track (timing error). That 800 mile error is assumed to be perpendicular to the track, and that's how it's averaged in.

So now you know how the cone is calculated. You can decide if it's of any value to you.

[caneflyer]

While NHC has changed the time period for their long-term means from 10 years to 5 years, they did not change how the cone is calculated. The cone is still (at least during 2006) drawn using the average errors from the last 10 years. And it only HAPPENS to contain the actual track 60% of the time - it wasn't drawn purposely that way.