Hurricane threat growing for Caribbean as long range outlook very uncertain

Morning model plots showing a general west track for the next several days.

Morning model plots showing a general west track for the next several days.

It has been a strange year for Atlantic hurricane activity. So many sputtering, long-lived but relatively weak systems have formed with minimal impact overall to land areas. Luck has been kind to us for sure but I am not so sure it can hold out for much longer.

We should have a tropical depression or possibly even a tropical storm by later today just east of the Windward Islands. We will know a lot more once the Hurricane Hunters fly out late today for on-site info from the low pressure area. Right now, it certainly looks like it is well on its way to developing but it needs a defined low level center of circulation and the recon crew can confirm whether or not that exists.

Whether or not this becomes a tropical depression or a storm before reaching the Windward Islands will not change the outcome for that region very much. Squally weather will move in beginning later tomorrow with tropical storm conditions likely across a good deal of the Windwards, especially to the north of where the center passes. Expect heavy rain, gusty winds and building seas as the low pressure area moves in.

Once past the islands, what should be Matthew at that point will have an opportunity to strengthen and become a hurricane. The upper ocean heat content in the Caribbean Sea is ample and could support a very intense hurricane if upper level winds allow.

As far as where the system tracks over the next five to seven days? More than likely, we’ll see a westward movement in to the central Caribbean not too far north off the coast of South America. As such, the so-called ABC islands could feel some impacts from this system. We simply need to wait and see to know the depth of those impacts as the week progresses.

Obviously areas such as Hispaniola, Jamaica, Cuba and the Cayman Islands should all be watching the progress of this system very closely. Before any possible impacts along the U.S. coast would happen, the islands along the northern Caribbean could be hit first. There’s no question about it, the next few days will be full of anxious moments as we wait and see how the steering pattern evolves.

A lot of talk has been made of recent runs of the GFS model which takes the storm/hurricane north out of the Caribbean and along or just off the U.S. East Coast. With a huge area of high pressure building over Canada and the Northeast this could be a bad scenario for a large stretch of coastline. But will it happen this way? It is impossible to know right now. Other model guidance shows a slower moving system that tracks farther to the west with potential tracks in to the Gulf of Mexico. Split the difference and Florida becomes a target.

So what do we do? My advice: just keep up to date with the latest info and be ready to react if this comes your way. No one has the answer right now. I sure don’t. It’s just like last year at this same time ironically when Joaquin was a threat to the Mid-Atlantic according to the American generated models. You remember that duel right? The Euro was the outlier it seemed and yet it turned out to be correct and Joaquin missed the United States. Right now we simply don’t have enough to go on in terms of making a forecast of where this ends up in a week to ten days. As I often say, it’s hurricane season and people should be ready for anything no matter what.

M. Sudduth 12:45 PM ET Sept 27

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New tropical storm likely to develop as 97L moves west towards eastern Caribbean

Invest area 97L poisted to become a tropical depression as it nears the eastern Caribbean this week.

Invest area 97L poised to become a tropical depression as it nears the eastern Caribbean this week.

It is remarkable how well the GFS model in particular has “advertised” what we are seeing now and will see in the coming days. I first mentioned the possibility of something emerging from Africa back on September 21 and ever since then, the GFS has been locked on. Now, several days later, we have invest area 97L with a 90% of becoming a tropical depression or stronger over the next five days.

Right now, the system is still gathering itself over the deep tropics. It has a large area of energy and plenty of moisture to work with. Water temps are warm and the upper level winds are favorable. All of the intensity guidance eventually strengthens this system in to a hurricane but not until the eastern Caribbean Sea.

First up will be impacts for the Windward Islands. While it’s impossible to know exactly where the center will track let’s not focus entirely on that right now. Instead, let’s look at the hazards that are likely headed towards areas such as Martinique, Saint Lucia, Barbados, Grenada and Trinidad and Tobago. At the very least, squally weather will build in by early Wednesday morning it looks like. Heavy rain with gusty winds along with rough surf and larger waves will accompany the system no matter how strong it is at that point. It would not surprise me at all to see tropical storm conditions for portions of the Windward Islands as it appears that the low pressure area will be strengthening as it passes by. This is what people need to be ready for and not focusing on the center of circulation once it develops. The effects will extend well beyond the center – I know most people should know this but a friendly reminder never hurts.

After entering the eastern Caribbean Sea, what should be TS Matthew at that point is likely to intensify and become a hurricane as the week progresses. Upper ocean heat content will increase dramatically for the system meaning that there is ample fuel for it to become a formidable hurricane.

So what happens next? Obviously a lot of people want to know the answer to that question. I simply don’t know at this point. We are faced with yet another challenging forecast period with all kinds of variables thrown in from the possible interaction with northern South America to upper level low pressure areas digging in like we saw last year with Joaquin and almost every other scenario in between.

The model guidance beyond five days has been interesting to say the least. I won’t pretend that people can’t see the output from various social media and other hurricane related websites. One run of a model will show a hurricane moving in to the Gulf of Mexico. Twelve hours later, that same model has it turning north near Hispaniola. Let me make this very clear: we are talking about predicting the movement of a very complex weather system that will be interacting with equally complex pieces of energy, land masses and other unknowns that will ultimately shape the outcome. To think that we will have the solution six to ten days out is not a good idea. The wild swings from the various global models will be very interesting to watch but beyond five days exceeds the grasp of most in the weather community, especially when talking about a potentially powerful hurricane.

For now, let’s see how things develop over the next 48-72 hours and for interests in the Windward Islands especially, it’s time to pay close attention and be ready for impacts by mid-week.

As for how the story ends? I guess we will all find out together.

I’ll have more here later today with my video discussion followed by another blog post late tonight.

M. Sudduth 6:30 AM ET Sept 26

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Karl headed out as we focus on next system

Satellite image showing low pressure area over eastern Atlantic. Most of the global computer models suggest it will gradually develop over the next several days as it moves west.

Satellite image showing low pressure area over eastern Atlantic. Most of the global computer models suggest it will gradually develop over the next several days as it moves west.

Karl passed within about 60 miles of Bermuda in the over night hours bringing tropical storm conditions to the area. The storm is now moving away and will do so with increasing forward speed throughout the weekend. Winds and seas will subside and by sunset this evening, it will be quite gorgeous in Bermuda. There is still a chance that Karl becomes a hurricane over the open Atlantic but it will only be an issue for shipping lanes.

As we say goodbye to Karl, we will need to become more and more vigilant as we monitor a tropical wave and low pressure area moving across the deep tropics. This one has potential for becoming a strong hurricane at some point as all signs point to a change in the conditions that have been preventing the storms this season from reaching their full potential.

The GFS model in particular has been extremely consistent with its run to run depiction of a gradually developing tropical cyclone headed right for the eastern Caribbean Sea. We’re not talking five or seven days out any longer, this looks like it could happen as early as Monday with a possible tropical storm threatening the Windward Islands.

Right now, satellite data indicates¬† a large area of energy associated with a tropical wave that moved off of Africa a couple of days ago. The moisture content is high, also known as precipitable water. There is increasing vorticity meaning spin in the atmosphere and water temperatures are plenty warm. I see no reason to believe that this system won’t develop as it moves steadily west over the coming days. In fact, the NHC is now indicating a 50% chance of development over the next five days and says that a tropical depression could form as it approaches the Lesser Antilles.

NHC graphical outlook map showing the increasing chance for development of eastern Atlantic tropical wave as it moves west towards the Caribbean Sea.

NHC graphical outlook map showing the increasing chance for development of eastern Atlantic tropical wave as it moves west towards the Caribbean Sea.

For now my concern is for the Lesser Antilles and specifically the Windward Islands. It is impossible to know which area could see the most significant impacts from a system that has not even developed yet. This one looks like the real deal and as such, interests in the Lesser Antilles and eastern Caribbean as a whole need to be paying attention to this feature. Even if it is slower to develop than the GFS is indicating, the threat of heavy rain seems to be almost a certainty at this point. Anything beyond that will be determined by just how quickly it organizes over the next few days.

I will be watching this system very closely. Look for an in-depth video discussion to be posted later this afternoon here, our YouTube channel and to our app.

M. Sudduth 7:30 AM ET Sept 24

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Tropics quite active as we enter second 10 day period of the month

Satellite photo showing 97L (left, near the Bahamas) and 98L (right, near the Lesser Antilles)

Satellite photo showing 97L (left, near the Bahamas) and 98L (right, near the Lesser Antilles)

There is quite a lot going on this morning with two very active systems in the Atlantic Basin. One is 97L near the Bahamas and the other, 98L nearing the Lesser Antilles.

First up- 97L. The small low pressure system has probably been a tropical depression for a few hours but it is not bothering any land areas so it does not really matter all that much. The NHC may upgrade it later this morning but the window of opportunity for it to intensify further is rapidly closing. However, the system has a vigorous and well defined low pressure area and is producing persistent convection and therefore has some time left to strengthen a little more. The big inhibitor will be very strong upper level winds that are approaching from the west. These winds will quickly disrupt the process of upward motion and shear out the low quite efficiently.

Next we have 98L which continues to get better organized as it approaches the Lesser Antilles. The main impact right now will be an increase in tropical downpours accompanied by periods of gusty winds. These conditions will spread across a good deal of the Lesser Antilles later today and through the upcoming weekend.

There is a good chance that 98L will become a tropical storm at some point over the next 72 hours or so and this could make for a rather stormy period for the islands. I do not see any solid indication that 98L will become a hurricane while passing through the region but its fairly slow movement means a prolonged period of heavy rains.

The steering pattern is such that we should see the system turn northwest and eventually north as it feels the effects of a strong trough in the western Atlantic. This is very common for this time of year and should easily turn what ever develops away from the Bahamas and Florida by early next week.

The remainder of the Atlantic and Caribbean are quiet with no additional areas of interest noted this morning.

In the east Pacific, there is a disturbance well to the south of Mexico that has potential for development as it moves westward and away from land.

I’ll have more on the two Atlantic features this afternoon with a complete video blog analysis posted to our iPhone app early this afternoon.

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