It seems to be happening more and more on social media – someone takes a model forecast image at 200+ hours out (8+ days) and posts about it as though it’s a lock to happen. Whether it was an epic snow storm this winter or a potential hurricane this summer, it’s bound to happen again. Take those long range images with a grain of salt. Long range model images aren’t forecasts at all – they’re guidance to be used by forecasters.
Some of you may have seen, or even shared an online forecast about an impending “major hurricane in the Gulf next week.” While I’m not saying that can’t happen, it’s far too early to say anything about this potential system with any degree of certainty or accuracy. After all, it’s not even a “system” yet…only a broad area of disturbed weather in the tropics.
Let’s take a closer look at the long-range American forecast model (GFS – Global Forecast System) for next week. This computer model is run four times daily and its output is readily available on any number of public websites.
For simplicity’s sake, I’ll focus on the same forecast time next week: 7 pm CDT Thursday, August 28.
I’ll start with the run from 7pm CDT on Monday. Here we are at 216 hours (9 days) from when the model began…notice anything suspicious or threatening? I don’t.
Let’s fast-forward six hours to the next run (at 1am CDT Tuesday). Now we’re 210 hours into the future, and it’s quite a different story in the Gulf.
Why don’t we take a look at the next run (at 7am CDT Tuesday)? I’d be concerned in the Valley if this is what actually happens! Remember, we’re at +204 hours (8.5 days) here, any computer model is highly inaccurate this far into the future.
Below is the model forecast from the run 12 hours later (that’s 7pm CDT Tuesday if you’re following along). Notice the “storm” has shifted well to the southwest.
At this point you may be asking yourself, what should I take away from all of this? The short answer, continue following trusted weather sources like Storm Team 48 or the meteorologists at the National Hurricane Center. It’s far too early to make any drastic decisions about next week’s weather. This computer model (and others) will continue shifting the intensity and track of this potential storm.
While this particular model has locked onto a something in the Gulf for now, there’s plenty of time for that to change. At 168+ hours out (7 days if you prefer), computer models are notoriously inaccurate. Some models are taking the storm up the East Coast while others bring it onshore near the US/Mexico border. Even this model shifts the storm position around quite a bit from run to run.
We’ll be watching things play out at WAFF, and we’ll let you know if/when it’s time to be concerned. It’s never too early to have an emergency plan in place, but right now, it is too early to hit the panic button.