Here we are again just a few weeks out from the Atlantic hurricane season beginning and we have something to watch in the waters off the Southeast coast.
The National Hurricane Center has outlined an area of interest associated with a remnant frontal system that has managed to park itself over fairly warm water (for this time of year). The atmosphere and ocean could work together to spawn a semi-tropical storm system later this week. Before anyone gets too worked up about it, let’s look at some facts.
First of all, it is May. We typically don’t see much tropical or sub-tropical activity during the month of May. However, of all the off-season months that we do get development, May is the most active. In fact, it is active enough, around two dozen or so developments over the past 100+ years, that I am not sure why the hurricane season doesn’t officially begin in May. That’s a story for another day perhaps.
This time of year, water temperatures are warming but are not typically warm enough to allow for the deep moisture content needed to support a tropical storm or hurricane. On the other hand, the southwest Atlantic is running a bit above normal right now with the 26C line (79.5F) extending northward out of the Bahamas just off the Southeast coast. This region of marginal water temp threshold is narrow and limited. It is surrounded by much cooler water temps, mid-70s or so. This gives us reason to believe that what ever tries to develop will have very limited conditions to work with.
The other aspect of this potential development, as noted in the NHC’s Tropical Weather Outlook (actually they issued a special version of it since it’s not officially hurricane season yet), is that the low pressure area that is forecast to develop is non-tropical in origin. This means it lacks the true deep warm-core structure that we see in say a tropical wave origin storm or hurricane. Take Gonzalo last October, its birth can be traced back to a tropical wave, full of heat and moisture, that emerged from Africa. The low pressure that is likely to spin up off the Southeast coast will come from a non-tropical environment off of an old frontal boundary. While this is often an excellent genesis point for tropical storms and hurricanes to grow from, it usually takes longer for them to acquire full tropical characteristics. This simply means that we are likely going to see a very shallow, limited convection based storm system develop by mid-week.
As far as impacts go, a storm over the ocean is always a concern for boaters and beach interests. An increase in swells, rough surf and winds along the coast from northern Florida up through the Carolinas is likely later in the week. Think of it as a kind of hybrid storm, not fully what we would look for during the height of the hurricane season. Thus, the bottom line here is that while it’s possible we’ll have something interesting to talk about this week, the effects will be confined to the coast and just inland and shouldn’t amount to more than passing rain showers, breezy conditions and rough surf.
One note about this: the North Carolina Outer Banks took quite a beating from a departing ocean storm late last week. Some beaches sustained heavy erosion and can ill-afford any additional aggravation right now. Hopefully this potential storm system will not meander far enough north to rough up the area any more than has already taken place. That being said, interests along the Outer Banks in the usual flood prone areas should pay close attention to what happens with this low pressure area. It’s been a rough few years, dating back to Irene in 2011. Since then, storm after storm has lashed the region and even weak systems add more to the problem.
I’ll have more here on this developing system throughout the week ahead. I’ll also be posting a video blog to our app, Hurricane Impact, as well as to our partner app, Hurricane Pro and HD, later today. It’s that time of year again, well, almost anyway…
M. Sudduth 9:10 AM ET May 4