Invest area 90L, which is tucked away in the northwest Caribbean Sea, just off the coast of Belize, is keeping a lot of people guessing as to what its eventual outcome will be. This is fairly typical of late May or early June tropical systems, especially in the Gulf of Mexico – which is where this system is headed.
So let’s start with what we know as of now:
NHC says development chances are now at 60% over the next five days. This means we could see a subtropical or purely tropical depression form before all is said and done. What ever it is classified as, it will have some negative impacts on Memorial Day weekend plans, including travel on the busy I-10 corridor and elsewhere.
Right now, the low pressure area is broad, diffuse and void of any solid thunderstorm activity. Dry air in the mid-levels plus strong upper level winds are keeping things in check for the time being.
As we head in to the weekend, the NHC mentions the fact that conditions are forecast to become more conducive for slow development and this is when we may see more organization of the system – perhaps enough so that it is classified as a depression. The subtropical label means it has a mix of mid-latitude storm features, a spread out wind field and a much broader area of overall impacts. On the other hand, a purely tropical depression or storm has a more compact wind and pressure field, tighter overall banding features and a smaller geographic footprint so to speak; in short, it’s more concentrated.
The label won’t matter – I am sure you have heard this a lot about this system already. It’s true – we name weather systems to give us clarity and a way to keep up with everything. The end result is what really matters and for 90L, and/or what ever it ends up being called, that means rain and a lot of it.
WPC’s 7 day precipitation map showing a huge area of potentially very heavy rain as the low pressure area takes shape in the Gulf of Mexico.
I have again posted the Weather Prediction Center’s 7 days precip forecast and it shows the potential for widespread heavy rain across a good deal of the Southeast, including all of Florida. Now, this does not mean that this map will verify as depicted, it is a guidance tool to indicate the potential for heavy rain across the region as the low pressure area moves slowly north towards the central Gulf Coast.
If you have plans to travel across the I-10 corridor this weekend, please pay close attention to local weather info and radar updates. Driving at 60-75 mph in torrential downpours can be hazardous to your health – take it from someone who has been in more rain than most people will ever see! Slow down, leave early and take this seriously. Rain is a hazard, even if it’s not causing major flooding like Harvey did last August.
For areas that receive sustained onshore flow, the possibility of large wave action and some minor to perhaps moderate coastal flooding will present challenges as well. We will have to watch this potential problem closely as we get further along in time and the low pressure area develops (or not) more. I suspect that some coastal flood watches will be posted at some point over the coming days.
The wind won’t be too much of an issue overall but consider this: if we get gusts to 45-50 mph in any heavier downpours or thunderstorms, plus the saturated ground, well then, you can imagine the trees with their newly dense leaf system could be toppled in some cases. Obviously, we need to wait and see how strong the low gets but be aware that power outages due to downed trees may be a problem where the wind gusts are high enough to lay some trees over.
So the bottom line is this: we have a real mess on our hands for a very busy weekend ahead. Millions of people will be hitting the road in anticipation of the start of summer. This low pressure system, what ever it ends up being called, will be an issue to contend with. Understanding the totality of the potential impacts is important so I encourage anyone with interests along the Gulf Coast and in to the Southeast to keep up with the latest as we move towards the weekend.
I will post a detailed video discussion later this afternoon and will go over the most updated computer guidance as well as focus on what impacts to expect.
8:40 AM ET May 23