Large low pressure area will bring a lot of rain, some wind and minor coastal impacts this weekend

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.

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.

M. Sudduth

8:40 AM ET May 23

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Chances for storm to form off Southeast coast going up

Satellite photo of invest area 90L off the coast of Florida

Satellite photo of invest area 90L off the coast of Florida

It looks like we may have a preseason named storm before too long. The NHC has increased the chances of development for what is now invest area 90L, just off the east coast of Florida. As of this morning, the odds were placed at 60% for either a subtropical or purely tropical storm to form over the next 48 hours or so.

As you can see from the satellite picture, the low pressure area is beginning to organize but it still has that spread out, subtropical look to it. This is common when seeing systems develop from non-tropical origins, especially this early in the (almost) season.

It is interesting to note that some of the computer models do suggest a quick transition in to a purely warm-core, tropical storm before it impacts the coast Friday or Saturday. Water temps are only just warm enough to support such a scenario but we have seen instances when storms have ramped up despite having less-than-ideal conditions to work with.

All that being said, it’s not the heart of the hurricane season and as such, we do not need to be concerned with a high-impact event. However, that is not saying that we need to downplay the impacts and ignore what ever forms off the coast.

At the beach, an increase in surf and associated rip-currents will be an issue from parts of Florida up through the mid-Atlantic. Check your local NWS site for more information specific to your area.

Breezy conditions are likely (winds are already picking up now here in Wilmington, NC where my office is) as the low takes shape and moves slowly northward. I suppose that there is at least a chance for tropical storm conditions in parts of the Carolinas along the immediate coast as we end the week. A lot will depend, obviously, on how well organized the storm becomes while over the warm water of the Gulf Stream.

The other impact will be rain, sometimes heavy as bands move onshore. This is likely to be more of a nuisance than a true flood threat. Any outdoor plans Friday and Saturday should take this in to consideration. We’re looking at a few inches of rain at the most since the system is likely to be rather shallow in terms of deep thunderstorm activity. This should help to keep the rain from being too heavy over a wide area.

The Hurricane Hunters will eventually investigate the area and we will know more about its structure and intensity at that point. This probably won’t be until tomorrow. Kind of ironic that they are touring in Myrtle Beach right now as part of the NHC’s East Coast Hurricane Awareness Tour. Timing could not be better, eh?

I’ll have more here tonight with a brief update. I’ll also post a video blog to our app, Hurricane Impact. If you haven’t opened it in a while, now is a good time. Check the video section later today, I will have the discussion posted by 1pm ET.

M. Sudduth 11:35 AM ET May 6

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Subtropical storm Fay develops, should bring squalls to Bermuda late this weekend

Subtropical storm Fay tracking map from the NHC

Subtropical storm Fay tracking map from the NHC

We have another named storm to add to the rather shallow list for 2014: Fay. It is not a purely tropical storm, so it is being called “Subtropical Storm Fay”. I covered this designation and the reason behind it in my blog post from earlier today. The bottom line is that it is not quite the same structurally speaking as a pure tropical storm would be but the effects are very similar.

 

For Bermuda, Fay will mean an increase in wind, seas and squally weather. Because the wind field of a subtropical storm is more spread out and less uniform in nature, the effects will be felt far away from Fay’s center.

The forecast calls for Fay to strengthen a little more before being absorbed by a larger weather system over the northern Atlantic. Top winds are forecast to be around 50 mph and again, these will be seen far away from the low level center unless Fay can quickly consolidate and become a more typical tropical storm with winds focused more around the center. Either way, this is not going to be a big problem for Bermuda, we’re not talking about a hurricane or anything close to it at this point.

Elsewhere, two more areas bear watching in the Atlantic. One of them, invest area 90L, has the potential of becoming a hurricane as it tracks generally west-northwest this weekend. Several of the reliable global models are quite aggressive with development and so it will have to be watched closely.

I will have more here over the weekend with updates posted to our Twitter feed: @hurricanetrack

M. Sudduth 5:00 PM ET Oct 10

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