Some Education About How Hurricanes and Forecasting Works

One thing that I despise more is newscasters that utilize fear-mongering to boost ratings during a major storm approaching. So I am not going to be posting any more reminders, rebuttals, whatever on anyone who wants to keep posting these various “look at all of these times models said a storm was going to go to X but it really went to Y!” posts. I’m too damned tired to do it anymore.

Every single one of those posts are wrong, misleading, poorly written, or contrived. Every single one of them fail to respect the fact that in every one of their cases, the eventual path/landfall was entirely within the NHC’s forecast cone of uncertainty, and that in every one of these cases the NHC essentially showed the final path in their warnings at least 3 days – and in some cases, 5+ days – ahead of time, all of which are remarkable.

Are models 100% accurate? Of course not. Are they generally good for <= 2 days from initialization? Yes. Do storms “suddenly” turn, or make “surprise” changes? Only if all you are paying any attention to is the NHC’s central forecast line. I continue to post on social media when people talk about these storms making “quick” turns, and I’ve asked each time if these people could show me one example where a named storm made a “sudden” change/turn that took it to a landfall which was completely out of the NHC forecast cone for a period that was <= 2 days from the forecast point, and no one has been able to take me up on that offer. It just doesn’t generally happen.

So, no, Charley didn’t make a surprise turn into Florida – it was inside of the forecast cone the entire time. No, Irma didn’t make a surprise turn into Florida.No, Katrina didn’t suddenly go to New Orleans without warning (it was in the original forecast cone 6 days before landfall, and was essentially directly targets by the forecast path 3 full days before landfall). All of these are bunk. The bottom line has, and always should be, that if you are located inside of the white margin of error in an NHC forecast, you should be preparing as though it’s a lock that the storm is coming straight to your house.

The 0Z GFS and GFS-Legacy models, after nudging westward during the 18Z runs and bringing the storm closer to the coast, have now edged back to the east. We’re going to see these adjustments throughout the next day or so as models continue to refine. The HWRF 0Z run brings the storm ashore around Ormond/Daytona Beach, and the Euro 0Z run is strangely missing tonight. Either my site I follow hasn’t gotten it yet or its delayed, not sure.

We need to watch tomorrow for updates and stay on top of it until we know how that blocking ridge is doing. Keep in mind if the models and forecast are remotely close that we’re going to be watching a storm literally creeping slowly along the coast, so it’ll take some time to work itself out.

Maybe a little tutorial on forecasting is needed for these people. I just made this comment on one of the newscasts. forecasting attempts to cope with the uncertainty of the future, relying mainly on data from the past and present and an analysis of trends. forecasting models answer what are the trends telling us. there is a most likely scenario called the trend line with a margin of error that uses + or -, thus the cone of uncertainty. the further in time you go, the greater the margin of error. with each model run, confidence continues to grow has to where the storm is going to go if the previous model runs hold.

When preparing for a hurricane is to look at all the data. Look at all of the model runs and pay attention to trends. Are the model runs staying consistent. Also, keep in mind the wind field. For example, hurricane dorian now has hurricane force winds that extend 45 miles from the center. Only the most destructive winds are around the eye wall. From that point and out 45 miles from there, are hurricane force winds ranging from 75 mph plus.

Pay attention to where the center of the hurricane passes. If you live 70 miles away from where the center of the storm passes, you will get tropical-storm-force winds, which is just a typical rainy day for all of us Floridians. Also, since the storm will remain off shore, that places the strongest winds off shore on the north side of the storm, and on the east side. The north and east side of any tropical system is the strong side. The left side is the weaker side.

I hope that this tutorial on how hurricanes work as well as how forecasting models work helps to educate you the next time you prepare for a hurricane.

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