This update is primarily intended as an anti-hype update. Also, this is a great time to ask questions for things that don’t make sense. If you don’t understand something, please do ask! I’m here to help and explain what it means.
I’m starting out with the NHC forecast track. As Rafael is forecast to strengthen to a major Category 3 hurricane making landfall in Cuba, people are going to worry about a major US impact.
A major US impact is extremely unlikely at this time.
The NHC forecast cone is the first “line of defense” to consider.
What this cone is visually telling you is that the system is expected to weaken from a Cat 3 hurricane back to Cat 1-2 as it moves west in the Gulf. Toward the end of the forecast period, there is a HUGE amount of uncertainty, as the system is forecst to weaken to a tropical storm.
But let’s delve a bit further:
The spag shows a rather uncertain forecast for the first 3-4 days, then even more uncertainty after that. It is likely that Rafael will be a hurricane somewhere between the Yucatan and Louisiana in the Gulf, but from there, it will either break north or south. If it breaks north, chances are that it will weaken and dissipate; if it breaks south, there might be a landfall in Mexico.
That’s essentially what this is telling us.
If you go back and look at the previous spaghetti models:
You can see that the models had been seeing this possible southern route, but a more likely northern route.
It’s also notable that you can see how the system has generally tracked within the spag from then until where it is now.
The amount of uncertainty there is toward the end of a forecast period affects my lack of surprise at a major location change in the forecast like this. That’s what I’m trying to explain.
Sometimes the steering weather patterns make it so we’re pretty sure where the system will be in even 6-7 days out. It’ll shift, of course, but nothing like this. This is a great example of how it’ll be another couple of days before we know where this thing is going.
That’s all for this update. Please ask questions!
On imgur: https://imgur.com/gallery/hurricane-rafael-update-no-us-threat-0ZlHPMh