Hurricane lesson: Better understand what 'cone' tells you

High vs low confidence in the forecast

By John Gaughan - Chief meteorologist

ssd.noaa.gov

JACKSONVILLE, Fla. - Once again, tens of millions are under the gun of a potentially severe hurricane. Many sitting impatiently with their smartphone or tablet in hand, or by their computer at work or at home hitting -- refresh, refresh, refresh.

Then as the newest model spills out, either a tightening in the stomach or a smooth exhale, depending on whether the forecast tracks have shifted towards or away from their homes.

Major Hurricane Florence continues to track west-northwesterly, taking aim at the North Carolina Coast near Wrightsville Beach. This part of Florence's forecast has a very, very high probability of occurring. Many beach communities will be devastated. 

It is what happens after that which is also so intriguing and potentially devastating to South Carolina.and possibly Georgia.

The two models and the official forecast from the NHC diverge this weekend.

See the image? This shows the National Hurricane Center's "cone of uncertainty".

Want a tip when interpreting this? 

When the cone is very tight (close together) it is basically a "lock" that this will happen. Conversely, when you see the cone look like a big bubble, it means there is little confidence or a very low probability this will occur.

There appears to be a huge loss of confidence after Saturday as the cone "bubbles outward".

Why? Well, once again, leave it to the Euro to lead the way. The Euro is indicating that Florence may ride down the South Carolina coast passing near Myrtle Beach to Charleston before, finally moving inland in Georgia. 

This would be quite the twist. 

What if it does? How does this impact Jacksonville?

Even if it tracked further south than this, the expectation would be that Florence would be nearly washed out before any impacts could be felt in Southeastern Georgia and North Florida.

But everything depends on the final track and storm strength.

The Euro model is released between 2-3 a.m. and p.m. each day.

I'll update this article with another tip on how to interpret hurricane models later, too...

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