Slower development means more of a chance for impact later

Recent satellite shot showing invest 99L and the limited convection associateed with it currently. This will allow the tropical wave to move farther to west since it will not be influenced by any weakness in the subtropical ridge, allowing it to turn out to sea.

Recent satellite shot showing invest 99L and the limited convection associated with it currently. This will allow the tropical wave to move farther to the west since it will not be influenced by any weakness in the subtropical ridge.

It looks as though the Main Development Region or MDR is still struggling in terms of the ability for tropical cyclones to take shape. The area between Africa and the Lesser Antilles is usually fertile grounds for development this time of year but it seems that for the past several years, dry air has been the rule. The result is we see vigorous tropical waves move off of Africa, various computer models over-develop them and then nothing much happens. It’s like the models (some, not all) are simply not “aware” of the dry, more stable environment that has become a semi-permanent feature of the deep tropics.

However, this is not necessarily a good thing in the end. I’ll explain why…

It is actually quite simple. The longer a tropical wave takes to develop, the farther west it will track. The low level easterly flow which is dominant in the tropics this time of year pushes the tropical waves generally westward. If they don’t develop at all, they often end up in the southeast Pacific and try to develop there. It’s when they don’t develop until they get past about 60 degrees west longitude that is problematic for land areas.

Think about it, a larger storm or hurricane in the atmosphere will more than likely feel the effects of the mid-ocean trough that is usually waiting to allow systems to turn north and eventually northeast and away from land. Sometimes, like 2008, the subtropical ridge of high pressure is so well established that even hurricanes such as Ike can make it from Africa to Texas. Obviously this is rare – otherwise no one would want to live on the coast of Texas or anywhere else for that matter – the hurricanes would be too numerous year after year.

On the other hand, a shallow tropical wave, void of deep convection or thunderstorms, can sail along with the easterly trades and gain longitude day after day. Eventually, conditions improve and a tropical depression forms. By now, the system is nearing the eastern Caribbean and it will most certainly bring squalls, heavy rain and brief high seas to the region.

Hurricane Earl is an example of this scenario. The parent tropical wave struggled as it raced westward across the tropical Atlantic and in to the Caribbean Sea. It was not until it reached the western Caribbean that it developed and became a hurricane. It made landfall in Belize instead of developing early, way out in the MDR, and turning out to sea.

So what does this have to do with anything currently going on in the tropics? Perhaps it has huge relevance. This is because as we watch the recent trends with 99L, we have seen some of the models delaying development until it is only a day or so away from the Caribbean Sea. This ends up sending a slowly strengthening tropical system in to the region, bringing heavy rain and other hazards to the region. Beyond that time frame, anything seems possible, including threats to the United States.

Even though we expect development out in the open Atlantic, just because it doesn’t happen there doesn’t mean it won’t happen at all. The farther west these tropical waves track, the warmer the sea surface temps get. It’s only a matter of time, I believe, until we see something strengthen quickly and close to home. I just don’t know whose home yet.

Bottom line – over the coming days we will see a lot of variations of the “end result” for 99L and perhaps even Fiona and soon-to-be 90L coming off Africa now. The down side to delayed development is that more people take notice when a hurricane is coming from seven to ten days out. It makes sense, the hurricane is there longer and it gets more attention and more people know about it. If it blossoms later, like Katrina did in 2005 (5 days from tropical storm to landfall) then it gives us all less time to react.

The next few weeks will likely be very busy with one named storm after another forming in the Atlantic Basin. Some will be possible impact threats, others will not. It will be important to keep up with what’s going on at least daily if not more. The advantage of seeing a hurricane coming from a week out might not be there and as such, being ready in case one pops up with only 72 hours to prepare will be more important than ever.

I will go over this topic in greater detail on today’s video discussion which I will post here. You can also follow along in our app, Hurricane Impact, available on the App Store. All of our blog posts and video discussions are posted to the app for easy access on the go. Plus, the app has incredible landfall features which I will talk about more when and if the time comes.

M. Sudduth 12:20 PM ET Aug 20

Plenty to monitor over the next several days but beware of “scary maps”

NHC map showing potential for development in the eastern Atlantic, spreading towards the Caribbean, as the days progress

NHC map showing potential for development in the eastern Atlantic, spreading towards the Caribbean, as the days progress

We have several areas to monitor in the Atlantic Basin and one area in the east Pacific. Fortunately, none pose a direct threat to land for the time being but one area, in particular, warrants close scrutiny in the days ahead.

First up, tropical storm Kay in the eastern Pacific. Not much to say here except that it will weaken as it tracks well off of the Baja peninsula and eventually turns westward over cooler water. I do not see any appreciable impacts from this storm for the southern Baja except some added moisture. Once Kay dissipates early next week, that should do it for the time being in the eastern Pacific with no additional areas of development seen.

Next we have tropical storm Fiona in the open central Atlantic. Top winds are only 45 mph with limited deep convection noted on satellite imagery. Overall the dry mid-level air, partly due to the incessant Saharan Air Layer (SAL), is keeping Fiona from strengthening and this will likely remain the case over the next five days. In fact, the NHC is forecasting the storm to weaken as it moves farther to the north and west, well to the southeast of Bermuda. While I do not anticipate any issues arising from this storm, we never just ignore them until they dissipate or are headed away from land areas.

Of greater concern, especially for the eastern Caribbean islands, is invest area 99L deep in the eastern tropical Atlantic. The NHC gives it a 50% chance of becoming a tropical depression or stronger within the next five days.

The overall envelope of energy with the tropical wave is impressive. The large sprawling size makes me believe that development will be gradual at best. The SAL is far enough to the north to allow for slow but steady organization and it should go on to become the next named storm. If so, it will be “Gaston”.

Computer models are very aggressive with strengthening, perhaps a little too much so. Most of the intensity guidance suggests 99L will become a hurricane but I think its large size and overall state of the deep tropics will limit intensification until later in the period.

Interests in the Lesser Antilles should be watching 99L closely. Almost all of the track models indicate a general westward movement in to the eastern Caribbean early next week. As we have seen time and time again, it does not take a strong tropical storm or a hurricane to cause life-threatening flooding. The people in parts of Louisiana know this all too well and we need only to look back at Erika last season as a reminder for the Caribbean. There’s not much you can do to prepare for heavy rain, just being aware and making sure there is safe haven is at least something as opposed to nothing.

There is no doubt going to be a lot of speculation about where 99L and its eventual transition in to a tropical storm (or hurricane) will end up. In today’s world, computer model forecast maps can be shared with literally millions of people at a moment’s notice. Under the wrong context, this can be harmful. Not everyone has the weather geek know-how to realize that a 5, 7 or 10 day map has extreme limitations. On top of that, graphs showing intensity will only lead to more anxiety when it is probably unwarranted.

My point is, we are likely going to have to deal with a tropical storm and possibly a hurricane some time next week. The first area of concern is for the eastern Caribbean Sea. Beyond that, it’s wait and see just like it has been since I began this site back in 1999. Sure, the Internet has made things a lot faster, more weather models are available and so forth but with great access comes great responsibility (sorry Spiderman, had to borrow your uncle’s catch-phrase). Staring at a map that shows a giant hurricane on it 10 days out is not helpful to most people. If you see such things in social media, say to yourself, “Hmmm, guess I better keep an eye on that one”. Worrying about it this soon is futile – instead, maybe do a little more to prepare in case this, or any future storm/hurricane, comes your way. I’ve said my piece on this issue but just know, it’s coming (the scary weather maps) and you’ve been warned. Be smart and don’t spread the fire by sharing such images.

Last in my list of things to cover, the NHC has highlighted the area just off the African coast, out in to the eastern Atlantic by a few hundred miles for possible development next week. This too is just something to monitor but hey, if you live in the Cape Verde Islands, you could be impacted by squally weather as this tropical wave moves by.

It’s getting towards late August and we were told this hurricane season could be the busiest in four years. So far, it has generally lived up to that expectation. We are headed in to a busy period with a lot to keep up with. Considering the world around us and the inherent, constant distractions, it will be more important than ever to stay aware and be ready….just in case.

I’ll have more in my video discussion later this afternoon followed by another blog post in the morning.

M. Sudduth 2:30 PM ET Aug 19


Erika gone, new tropical storm developing near Africa, Pacific as busy as can possibly be

NHC map showing remnants of Erika (orange) and invest area 99L (red)

NHC map showing remnants of Erika (orange) and invest area 99L (red)

There is a lot to talk about today. I do realize it is also the 10th anniversary of Katrina’s historic landfall but instead of piling on more about that right now, let’s save it for another time, another in-depth blog post perhaps. For now, let’s focus on the current goings on.

Erika caused quite an uproar this past week with model mayhem galore. One day it looked like Florida would see an end to the hurricane drought. The next day, look out Carolinas! It just went on and on and yet Erika completely failed to behave as the models suggested – most of them anyway.

Now, to be clear, Erika had major consequences for some locations in the Caribbean Sea. Dominica has had terrible loss of life and an overwhelming loss of infrastructure. All of this due to one seemingly benign effect: rain. Over the centuries, I bet freshwater flooding has led to more misery than any other hazard from tropical cyclones. Storm surge poses the greatest risk in any one vulnerable location but flooding from too much rain seems to rear its ugly head one time too many as of late.

Erika is now just a remnant low moving across the southern portion of the Florida Straits. I do not see anything that leads me to believe that it has a chance of any significant comeback. While we need to certainly monitor its progress in case of any surprise endings, I wouldn’t worry too much about the left-overs becoming more than a nuisance – though it might bring heavy rain which of course has its own potential for causing issues.

Invest area 99L just off the coast of Africa

Invest area 99L just off the coast of Africa

Meanwhile, another strong tropical wave and associated low pressure system just off the coast of Africa is likely to be our next named storm: Fred. However, it won’t last very long. The favorable environment that it is currently a part of will be short-lived. It will be interesting to see the effects on the Cape Verde Islands as it looks like the system will pass over that location while intensifying some. I fully expect it to die out over the open eastern Atlantic some time next week.

One thing to note – if this system (99L) does in fact become a tropical storm or even a hurricane, it will be the third in a row to come from the so-called MDR or Main Development Region. I bring this up because this alley-way was supposed to be almost completely dead this year due to hostile conditions. I believe the warmer than normal water that has developed across much of the MDR has changed things somewhat. But, the upper level winds are still just too strong and as we saw with Danny and Erika, we may have MDR development but it will be tough for it to survive or thrive very long.

In the Pacific, we have three incredible hurricanes going on at once: Kilo, Ignacio and Jimena. None pose a substantial threat to land but all three are a testament to the remarkably warm water of the northern Pacific Ocean. This really has little to do with the El Nino itself, just a much warmer Pacific, away from the Equator, than we are used to seeing.

Hurricane Ignacio forecast track map from the CPHC

Hurricane Ignacio forecast track map from the CPHC

Hurricane Ignacio could bring tropical storm conditions to parts of Hawaii and as such, the Central Pacific Hurricane Center has posted a tropical storm watch for the Big Island. As long as Ignacio remains on track, the overall impact will be minimal to the area.

It has been a busy couple of weeks and it looks to remain that way going forward. So far, the United States has had little to deal with from the tropics. As we saw 10 years ago, that can change and have long-lasting effects that linger for generations. As August draws to a close, we know that September is traditionally the peak month for hurricane activity. We’ve been fortunate so far in 2015 (except for Dominica) and we can hope to have a quiet second half ahead of us. Only time will tell.

I’ll have more here tomorrow.

M. Sudduth 5:10 PM ET August 29

Tropics getting more active as favorable conditions show up in western Atlantic

99L well on its way to becoming a sub-tropical storm later today

99L well on its way to becoming a sub-tropical storm later today

The Atlantic hurricane season is about to get busier than we have seen it in quite some time. By later today, we will likely have a new sub-tropical storm (more on what that means in a moment) and a new area has developed east of the Lesser Antilles that needs to be watched closely in the coming days.

First, invest area 99L, which is situated to the south-southeast of Bermuda by about 600 miles or so, looks poised to become the next named storm in the Atlantic. However, it is not purely tropical in nature and resembles a blend of a mid-latitude storm system with more of a comma shape to it. This means too that the wind field is not as symmetrical as what we would expect in a purely tropical storm. In this case, most of the strong winds will be felt on the north and east side of the large center of circulation. In a well-developed tropical storm or hurricane, the wind would be more focused near the center and in all quadrants (at least to some extent).

The developing storm has very warm water underneath to work with and this is driving areas of very deep convection which could help to strengthen it enough to be classified and get a name later today. If this happens, the name will be Fay.

Interests in Bermuda should closely monitor the future track and intensity of this system as it could pass fairly close by later this weekend. In this case, if it passes to the west of Bermuda, then the effects will be significantly stronger than if it passes to the east. It’s too soon to know for sure just yet how this will play out but an increase in winds and seas, along with general squally weather, is likely for Bermuda in the coming days.

Once past Bermuda, the low should move on out in to the open Atlantic and not pose a threat to the United States except for an increase in swells some time next week.

Two other areas to watch in the tropical Atlantic

Two other areas to watch in the tropical Atlantic

The next area to watch is a tropical wave well to the east of the Lesser Antilles, over the tropical Atlantic. This area has not been favorable in recent weeks but things are changing within the atmosphere and it is likely that we will see something develop out of this feature.

Water temps are still very warm in the western Atlantic and now upper level winds are becoming more favorable as the MJO or Madden-Julian Oscillation becomes more conducive in the Western Hemisphere. This allows for a protective bubble, if you will, of upper level winds that allows for upward motion in the atmosphere. It is this upward motion that is needed to allow for convection or thunderstorms to form and flourish. We are entering a period of time where by this pattern will favor development across the western Atlantic.

Computer models are in excellent agreement that we will see a tropical storm, perhaps a hurricane, form from this system. This time, we have the GFS and the ECWMF models showing development. It would not surprise me at all to see two named storms develop within the next five to seven days.

So far, the global models suggest that any development that takes place would steer north of the Lesser Antilles enough to warrant only minor concern there. However, it’s early and we’re talking about the very beginning stages here, probably too soon to worry about track, there will be plenty of time for that later on.

Last, but not least, a large area of convection, associated with a tropical wave, is noted just west of the Cape Verde Islands. This area is typically not favored this time of year but it too looks like it has potential to develop more in the coming days. The NHC did not mention it just yet in their outlook but I think it’s coming sooner or later. We will have a lot going on as we progress through the weekend.

Did I mention it’s not over until it’s over? I think we are going to get a solid lesson in that before the month is out.

I’ll have more here later this afternoon.

M. Sudduth 9:00 AM ET Oct 10

Invest 99L doesn’t look like it will amount to much

Invest 99L well to the southeast of Bermuda

Invest 99L well to the southeast of Bermuda

There’s only one area in the Atlantic to discuss and that’s invest area 99L. Remember, the NHC designates suspect areas with a number and letter system to help keep track of what’s what and to allocate resources such as computer models and satellite imagery. The numbers 90-99 are used followed by the letter “L” for Atlantic. So, now that we are caught up on that, here’s the latest on the newest invest area, 99L…

As you can see in the satellite image, there’s not much to it. We have a rather broad area of low pressure at the surface that is interacting with an upper level low pressure. It is possible, considering the warm water underneath, that the system could become more organized over the next few days, enough so that a tropical or sub-tropical depression could form. Basically this tells me that what ever becomes of it won’t be much more than a nuisance and that is just for Bermuda if it passes close enough. Interests there should keep an eye on it as some squally weather could move across the area this weekend, possibly bringing tropical storm conditions for a brief time before it moves on out in to the open Atlantic.

Elsewhere, not much going on at all as the very sluggish Atlantic season continues to march on. We do have a period of time coming up where the upper level winds are forecast to become more favorable but that is still a week to 10 days away. For now, and as we head in to the weekend, no worries in the Gulf of Mexico or the Caribbean Sea.

I’ll post more here tomorrow morning about 99L and its potential impact on Bermuda.

M. Sudduth 4:45 PM ET Oct 9