From Meteorologist Liam Healy:
While we don’t think much about the tropics here in WV, its never a bad idea to keep an eye on them, especially if you’re a weather geek like myself. Hurricane Season officially starts on June 1st, but things sometimes get a bit of a head start and it’s not that uncommon believe it or not. Since 1852 (the beginning of the National Hurricane Centers database) 40 named storms have formed in the month of May! Now obviously, that’s not very many when you spread it out over 150+ years, but it’s still an interesting fact.
Based off of the graph above it’s obvious that while May, June or even the first half of July aren’t the most active months storms are still liable to form. Which brings us to the topic of this blog! We are tracking some potential tropical development in the next 5 days off of the Southeast US coast. It has a ‘High’ or 70% chance of formation according to the National Hurricane Center or NHC. If it does manage to form, and organize into a storm with winds of 40 mph or more, it will be named Arthur, the first name on the list for this years Hurricane Season.
To preface, this is not expected to be a hurricane, or even a tropical storm but something we refer to as a sub-tropical depression. One of the main differences, without going to deep into the science, is that a tropical system doesn’t have any fronts associated with it, but a sub-tropical depression will.
One of the tools we tend to use when talking about tropics are Sea Surface Temperatures or SST’s, and it is quite warm down there. In the Gulf SST’s are in the low 80’s, and off the Southeast coast they’re in the upper 70’s. Heck if we weren’t in the middle of a pandemic, I’d be calling out and hitting the beach with water temperatures like that! Okay, now back to the weather stuff… A baseline often used in forecasting for the tropics is 80° water temperatures and above are ideal for the formation of a tropical system. So we have a few of the pieces more or less there already for this to come together.
Next we need a low pressure system, this is the heart of any storm tropical or not! At the moment there is none because it hasn’t formed yet. Over the next few days what is called a stationary front, or just a front that doesn’t move, is expected to develop off the Florida Keys. This will bring some heavy rain and thunderstorms to Florida and the surrounding islands, but more importantly a ‘wave’ of low pressure is expected to develop along the front. This low pressure is what will become our suspected sub tropical cyclone!
While this isn’t expected to be strong, or even make much of a direct impact to land, it’s an interesting little feature to watch over the next few days, and with another active season expected we’ll have to watch and see what else might form as we get into the summer!