Re: their 11 AM video was very good
Posted by
Chris in Tampa on 8/29/2019, 5:09 pm
It was 4:30 into this video:
https://www.facebook.com/NWSNHC/videos/773188993099825/
The most recent was a different video if that was the one you looked at.
Ken Graham: "A lot of questions about... the cone and... we talk about the uncertainty and Dan Brown's on to it... he's in the hot seat... related to the... the hurricane issuing, the forecast... Dan, getting a lot of questions about ... wow, that's a big cone... but, we're... we're still far out really, relatively... with the forecast... so you know we have some time. Why such a variability?"
Dan Brown: "We're still seeing, ya know, various spread in the model guidance. It's... very common... at this stage in the game. I just put up here all the ensemble members... so we run various models... many times... this shows both the U.S. GFS model and the European model ensembles [all run] last night. So you can still see that there's a range of possibilities, really... anywhere along the Florida east coast at this time and that's why that cone is so large, it still encompasses the entire... really... east coast of Florida. So... again, the forecast will narrow ... hone in on an area as we go through the next few days."
He makes it sound like the cone is based on the current model guidance rather than the NHC's error over the past 5 years. (not including this year) It's live, and the question was kind of rambling, so I guess that's it. I guess he was just mixing up the question about the cone with just general uncertainty. Even if there was huge uncertainty 24 hours before landfall, the cone would still be very small over the first 24 hours, based on just the 24 hour error circle based on 5 years of NHC errors.
The current cone would be the same if every model picked the same exact location 5 days out or if the spread was a 1,000 miles wide in the models and it would be good if they got that right each time. Approximately 2/3rds of the time, a storm will remain in the cone and approximately 1/3 of the time, it won't be. That's just how the cone works and I think a lot of people see the cone as something definitive. If you are out of the cone, you're safe, which isn't true. And then of course, that's the exact center of the storm, not it's impacts, which could extend over a 100 miles or more in some storms, well outside the cone. It's good to reiterate that when possible. But again, it's live. |
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