If you’ve been following the news at all lately, you’ve likely heard about now-Category 4 Hurricane Florence currently over the open waters of the Atlantic Ocean. In just 24 hours, Hurricane Florence went from a relatively non-threatening minimal storm to a dangerous category 4 hurricane with winds of 130 mph. Let’s take a closer look.
Florence continues to strengthen this evening, but shouldn’t become much stronger over the next few days as shear begins to increase in its path. Normally hurricanes well out in the Atlantic aren’t discussed in the mainstream media until they are more of an immediate threat to land, but with modern social media and some extra hype as well as some rapid intensification, Florence has already been making headlines as a storm that could potentially bring big issues to the US sometime later next week. With so many sources available online, those who aren’t weather experts have to wonder: Is this just more hype, or is there a legitimate hurricane threat to the eastern seaboard coming in the next 7 days? Well, don’t worry. We’ll break down exactly what you need to know at this point in time, and also discuss what’s left to figure out before sounding the alarms for a landfalling east coast hurricane.
Wednesday Morning Category 3 Hurricane Florence
Mesoscale vs Macro-scale Analysis:
Don’t worry, this sounds more complicated than it actually is.
There are two important perspectives that need to be taken into account when analyzing a hurricane like Florence. One is the mesoscale analysis of a hurricane, which takes into account some of the more micro-scale variables like strength and movement of the storm, and the other is the macro-scale analysis, which takes into account the larger overarching pattern and features that might have an influence on a given hurricane. Both of these are crucial in determining the future of Hurricane Florence, and both of these can be rather difficult to predict, even just several days out.
On the mesoscale level, we have a rapidly strengthening major hurricane that is already exceeding expectations and forecasts. Florence has taken advantage of the environment around it better than what was modeled by computer guidance. The storm is also positioned slightly further north than most models. These smaller features can actually end up having a much bigger impact down the road than most think, especially with a setup like this.
On the macro-scale level, we have an unusually large ridge placed over the entire central and eastern half of the United States. This ridge will be one of the most important features in dictating where Florence will end up 4-7 days from now. A stronger ridge that is more difficult to break through directly on top of a hurricane will force it to move further west and towards the coastline, while a weaker ridge could allow the storm to slip through and head harmlessly out to sea.
Breakdown of the Future of Hurricane Florence / WeatherOptics
The team at WeatherOptics has put together this graphic to try and break down everything (both on a mesoscale and macro-scale level) that could impact the future track and strength of Hurricane Florence. We’ve labeled each important feature to make it as simple as possible to understand exactly what’s going on, and the questions that we need to answer before trying to determine whether or not this is an actual threat to the eastern seaboard.
1. Strength and Position of Hurricane Florence:
Hurricane Florence Model Intensity Guidance / TropicalTidbits
Starting off with some mesoscale analysis, the exact strength and position of Florence at each given hour will have an impact on what happens 7+ days out. A stronger hurricane that is further to the north has a better shot at gaining more latitude, thus being put on a path further to the north than modeled. A stronger system could also have an easier time breaking through or finding a weakness in the ridge to the north. In other words, stronger storm –> further north storm –> easier time breaking through the ridge –> better chance of heading harmlessly out to sea.
While Florence may currently be stronger and further north than modeled, it has a long road ahead. We can already see from the shear out ahead of it that things won’t necessarily be smooth sailing from here on out. Most guidance suggests that Florence is hitting a peak state of intensity right now, and will likely weaken before entering another period of intensification. Future weakening and shear could steer the system back south and bode better towards a solution that brings the storm closer to the US coastline. Not good. We’ll have to continue monitoring this hour by hour.
2. Strength and Position of Ridge:
12z GFS showing massive ridging overhead Florence @ Hour 156 / TropicalTidbits
The massive ridge that has been situated over the entire central and eastern US for several weeks continues to redevelop, refusing to budge very much. Anytime this is the case during hurricane season, forecasters are typically on high alert because it means there’s an “open entrance” to the eastern US coastline. Any system that gets trapped underneath this ridge automatically has a higher chance of impacting the mainland because it’s very difficult for a storm to break through to the north, and it ends up having no other choice but to go due west.
We are dealing with a highly unusual ridge in its strength, size, position, and consistency. We already know that there is a high chance with Florence’s current movement that it slips underneath this ridge. The real question is, does it become trapped under and forced west? Or does it find a weakness in the ridge that allows it to escape out to sea? This is something that we probably cannot answer for another 2-3 days, and would be foolish on anyone’s part to try to predict right now. We need to continue seeing updated model information and data before we can say anything definitively.
If we break down the scenario even further (which we’ve done for you of course), a weakness in the ridge (4 / B) makes for an easy escape off to the north and east. But on the other hand, a ridge that continues to develop on the east side and doesn’t form a gap between A and B will literally force the storm into the coastline. At the same time though, If too much strength builds up on the eastern side, and we see something similar on the western side towards the central US, a strong storm like Florence could find enough of a gap (or even create its own) to miss the East Coast altogether. Again, we won’t be able to determine how this shapes up until more model guidance data becomes available for us to analyze.
3. Strength and Position of Northern-Atlantic Trough:
12z GFS showing developing N-Atl Trough @ Hour 216 / TropicalTidbits
A digging trough over the north-central Atlantic Basin will also have the potential influence Florence and its future track. Model guidance is trying to decide the strength, size, and movement of this trough, but is struggling considerably. There are a few scenarios here to watch for, stay with us here. If the trough digs deep enough and expands out far enough to the west, it will push the ridge to its west further overtop of Florence and possibly even aid in some strengthening. This will make it harder for the storm to escape out to sea, as we previously discussed. On the other hand, a drifting trough that doesn’t expand and does not dig as much will allow the ridge overhead to expand out more, becoming more loose and giving room for potential weaknesses to develop. This would allow Florence to have a better shot at escaping.
Clearly long-range hurricane forecasts like this are not easy. There are so many players and moving parts, each changing if and how they are affecting the system, that to make definitive forecasts at this point wouldn’t do any good. As more data becomes sampled and we move closer to the actual “potential impact date,” many of these features will become more clear. Again, that won’t happen for another 2-3 days at least. In the meantime, it’s important to keep an eye on overall trends. Are models showing stronger and stronger ridging? Does Florence go into a period of substantial weakening or remain relatively unharmed? These are questions we’ll be asking for you. We’ll be consistently updating our analysis over the next 7 days, will work to continue to provide you with the best coverage and information possible. Expect another large update on Hurricane Florence tomorrow.