The next five days

GFS model output showing the position of what would likely be a hurricane at day five. Here we see it approaching eastern Cuba after passing east of Jamaica and very close to Haiti.

GFS model output showing the position of what would likely be a hurricane at day five. Here we see it approaching eastern Cuba after passing east of Jamaica and very close to Haiti.

The very latest from the NHC indicates that we still do not have a tropical depression or a tropical storm from invest area 97L. In other words it remains a very well organized tropical wave of low pressure. That being said, it is producing winds of 40-45 mph in some of the heavier squalls as the entire system moves off to the west at around 15 mph. The Hurricane Hunter crew is currently flying through the area to sample the wind field and we will know by later this morning whether or not this is officially a tropical storm.

On the current track, the organizing system will pass through the Windward Islands today and bring with it more squally weather which will mean tropical storm conditions in some locations. Fortunately the low did not intensify quickly and as such we are not too concerned with much more than moderate tropical storm conditions at worst. By tomorrow, winds and seas will subside across the region.

Once the wave moves in to the eastern Caribbean Sea it is almost certainly going to strengthen. Water temps are very warm and the upper levels of the atmosphere support development. Some models are more robust than others but the bottom line is that this will be on its way to becoming a hurricane with time.

The track over the next five days will be very important for several reasons. First, we could see impacts as far south as Aruba, Bonaire and Curacao as what will eventually be a tropical storm passes by. Just how close to the north coast of South America this tracks remains to be seen but it is possible that it will be close enough for an increase in wind and rain by the weekend.

By late in the weekend and in to Monday, we should see a turn to the north as the western portion of the ridge of high pressure over the Atlantic begins to erode some. This will allow the sharp turn to the north that we are seeing in the model guidance. Some people have asked me how this is possible and has it happened before? It is possible due to the fact that the high pressure area, which is more dense an air mass than the tropical cyclone, relaxes some and allows the would-be hurricane to move north with time. It’s like holding a helium balloon down with your hand – once you move your hand away, which is essentially a form of high pressure, the balloon drifts up and away.

This type of set up was seen a few times in history but perhaps the most infamous was Hazel in 1954. Its track looks similar to what the models are hinting at for this system.

Around the five day time frame, it is possible for Jamaica, Haiti and Cuba to begin feeling the effects of what is more than likely going to be a hurricane. The GFS model is slightly east of the ECWMF or Euro model. The GFS moves the system over eastern Cuba and misses Jamaica but just barely. On the other hand, the Euro takes the center across Jamaica and then in to eastern Cuba. Obviously this needs to be monitored very closely by interests all along the islands of the Caribbean.

What happens after five days is the subject of much debate. Since we can all see the long range models now thanks to access on the Internet I won’t pretend to ignore it. Yes, I see the landfall in eastern North Carolina in about nine days. I also see the Eruo model taking a much slower path with a turn back to the northwest towards Florida by days nine and ten. I caution that these are extreme time frames when it comes to any large scale weather feature let alone adding a hurricane to the mix.

I for one am glad to see people talking about the models and the potential for impacts. It shows that people are in fact aware – it has their attention. That is a positive thing. We are so distracted by everyday news of politics, local and national issues, etc. that sometimes a bull horn is what we need to get people to pay attention. Knowing that there is a possibility of a hurricane threat for your area 10 days out is enough to get people motivated to at least keep track of it. Most people do not adequately prepare as they should well ahead of a landfall. Maybe the age of social media and the ability to share long range forecasts is not such a bad thing simply because it raises much needed awareness. No one I know is actually scared of a map. If they are, they need to dig deeper and ask questions about what the map means and how it might change. Social media allows for that too; it gets people engaged and talking and that is an advantage that many people can use.

So for now, let’s see what the Hurricane Hunters find and hopefully we can begin calling this what it is destined to be: Matthew. From there, the next five days are fairly straight-forward with regards to what happens. After that, no one knows for sure but it is great to see people paying attention.

I’ll have more later today.

M. Sudduth 8:15 AM ET Sept 28

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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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Danny will bring some rain (not nearly enough), a little wind but not much else

Recent satellite photo of TS Danny. You can clearly see the low level center becoming exposed on the southwest side of the storm

Recent satellite photo of TS Danny. You can clearly see the low level center becoming exposed on the southwest side of the storm

Danny is getting closer to the Lesser Antilles and will pass through over the next day with little more than some passing squalls and increased surf. The one-time category three hurricane is now fully engaged with stronger upper level winds than it can handle, coupled with drier mid-level air. This has led to quite a weakening trend which was exactly what was forecast to happen as of late.

For interests in the Caribbean, Danny will bring much needed rain but it won’t even begin to put a dent in the long-term drought that has affected the region. I suppose every drop counts and it’s better than nothing and certainly better than say, a category three hurricane bearing down.

I think it is safe to say that Danny will be all but gone by mid-week, chewed up by strong upper level winds and running over land that will further gut the storm down to little more than a low level swirl. That’s the circle of life in the tropics sometimes.

Meanwhile, we will need to be watching invest area 98L quite closely in the coming days as it looks to be well on its way to becoming a tropical depression. The models are not much help. One run can show a significant hurricane heading west while another run has barely anything at all. The only sure thing is that it is far from land and we have plenty of time to monitor its progress as the new week begins.

In other news, it was 10 years ago today that I began my planning for what would become hurricane Katrina. There is a lot that will be said by many people who had to deal with not only that historic hurricane but also the unprecedented 2005 season as a whole. I will have a separate blog post on this topic later in the coming week.

M. Sudduth 4:50 PM ET August 23

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Danny prompts tropical storm watch for portions of Caribbean islands

Danny put on quite a show yesterday, becoming the first major hurricane to form in the MDR or Main Development Region in quite some time. Its small size almost certainly aided in its impressive strengthening, shielding the tiny core from any dry air intrusions.

Things are different today for Danny as it heads in to a region where stronger upper level winds will pound away at the deep convection located around the center. This will also help to force drier mid level air in to the core which will induce fairly rapid weakening. As such, Danny is forecast to be of tropical storm intensity once it reaches the vicinity of the Caribbean Sea. In response to this forecast, several governments of a handful of Caribbean islands have issued a tropical storm watch (see graphic). This does not mean the center of Danny is expected to pass over any particular location but rather that tropical storm conditions are possible within the watch area within the next 48 hours.

I think that most people in the region will welcome Danny because of one major benefit that it will bring: rain. The Caribbean is going through a serious drought right now and any rain will at least curb the situation even if only a little bit. Fortunately, Danny is not a large, moisture-rich hurricane and thus it won’t be able to dump more rain than the region can handle. Perhaps this truly will be a small blessing for the region as Danny passes by over the next few days.

The forecast is interesting beyond the next three days as models have shifted the track of Danny more north with time. In fact, it won’t surprise me at all to see Danny’s center miss the Caribbean islands entirely. This would keep what ever center remains intact after doing battle with the dry air and shear over very warm water. That is probably going to be the only plus in Danny’s favor as most of the reliable computer guidance strongly suggests that Danny will weaken to a tropical depression and likely dissipate in to a trough of low pressure as it travels close to the southern Bahamas. It goes without saying, you never just ignore a tropical system in late August in the southwest Atlantic – we’ll see what happens with the modeling in the coming days but odds favor Danny being very weak to non-existent by early next week.

Meanwhile, another area not too far off the African coast is being monitored for possible development over the coming days. Water temps are plenty warm and it seems that the dry air is not much of an issue over much of the tropical Atlantic right now so we may see a period of time with several named storms coming up as we head in to September. So far, with the exception of Danny, none pose a threat to land and all will give us plenty of time to monitor.

Out in the central Pacific, tropical storm Kilo has managed to kick up quite a bit of buzz about being a possible threat to Hawaii. So far, it looks like the storm (and probably a hurricane at some point) will track well west of the string of islands before it turns back to the north and east. Of course, it needs to be monitored to make sure that does in fact happen. Hurricanes approaching from the south are much more likely to impact Hawaii than those tracking in from the east. Hurricane Iniki in 1992 comes to mind but it looks like Kilo won’t be a repeat of that event.

I’ll have a Saturday edition of my video blog posted later this afternoon and will go over in great detail what the impacts from Danny are likely to be for the Caribbean.

M. Sudduth 1:35 PN ET August 22

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Tropics becoming busier as Danny makes a run at becoming a hurricane

Recent microwave imagery showing a clearly developed core of Danny

Recent microwave imagery showing a clearly developed core of Danny

It is approaching late August and all of a sudden the tropics are becoming increasingly busy. We have TS Danny which is probably on its way to becoming a hurricane as well as two other areas of interest to watch over the coming days.

First up, Danny. The little storm has really come to life overnight with a clearly defined eye and eyewall developing as seen in every aspect of satellite imagery. The little bit of room that the storm has for developing is being taken advantage of and it won’t be long now before Danny is a hurricane.

The really interesting aspect to this is that Danny is small in size and so its environment currently in a favorable state makes all the difference. Water temps are warm, shear is light, outflow seems excellent and the dry air has been dealt with for the time being. However, things can and likely will change in a hurry for Danny – no matter how strong it gets in the near term. Its small size is a positive for its growth now but will be a drastic hindrance later on as stronger upper level winds await to the west.

5 day forecast track for Danny as of 5am ET Aug 20

5 day forecast track for Danny as of 5am ET Aug 20

The official forecast from the NHC takes Danny in to the northeast Caribbean during the early part of next week which means some impacts are expected for the region. How much wind and rain accompanies Danny remains to be seen. Obviously, it all hinges upon whether or not the hostile conditions play out as forecast by the major computer models. If all goes according to the forecast, Danny will encounter rather strong shear and this will literally inject any dry mid-level air still around directly in to the core of the storm/hurricane. This is where Danny’s small size can play against it – only a modest increase in shear can easily displace the convection or thunderstorms away from the low level center and weaken Danny rapidly.

We have plenty of time to watch and see how things evolve. The hope by many I am sure is that Danny brings much needed rain to parts of the Caribbean without all of the other nasty side-effects. We will get a better idea of what to expect over the next couple of days but odds are, Danny won’t pose much of a wind threat but it’s not prudent to ignore the storm either. Rain and too much of it at once can be a big problem too, especially in mountainous areas and as such, Danny needs to be monitored closely by interests in the northeast Caribbean.

Two-day tropical weather outlook map from the NHC showing the increasingly active pattern across the Atlantic Basin

Two-day tropical weather outlook map from the NHC showing the increasingly active pattern across the Atlantic Basin

Elsewhere, a complex weather pattern is developing in the vicinity of Bermuda (designated by the NHC as 97L) that could eventually lead to a subtropical storm taking shape. As I said, the situation is complex and involves an upper level area of low pressure interacting with a surface trough. The two will basically intermingle and produce what will best be described as a hybrid type storm or as we know it, subtropical storm. Water temps are certainly warm enough that it’s not out of the question for the system to take on more tropical characteristics but probably not before moving on to the north and away from Bermuda.

Meanwhile, another tropical wave moving off of Africa is likely to try and develop over the coming days as we see conditions becoming more favorable out that way. There is less and less SAL or Saharan Air Layer which means less dry air to battle with. Most global computer models show this next system developing and moving generally west with time. Obviously, we will have plenty of time to track it and observe as the pattern ebbs and flows so no need to worry about it just yet.

Model plots for Central Pacific area of interest 93C

Model plots for Central Pacific area of interest 93C

And not to ignore the Pacific – we have an area of interest, designated as 93C for Central Pacific, well to the southeast of Hawaii. This system looks like it has a strong chance of becoming a hurricane and possibly threatening the western extent of the Hawaiian Islands. Interests in the region should closely monitor the progress as history has shown us that hurricanes approaching from the south are far more dangerous for the area than those coming in from the east. The Central Pacific Hurricane Center will be handling the advisories for 93C once it becomes a tropical depression and eventually a named storm. I’ll have more on this developing situation in the coming days.

Farther to the west a pair of typhoons are roaming the warm waters with typhoon Goni expected to pass fairly close to Taiwan this weekend before turning northward – perhaps towards southwest Japan. There is certainly plenty to watch across the tropics as we head in to the last third of August.

I’ll have an in-depth look at Danny and the rest of the tropics in my video discussion to be posted later this afternoon.

M. Sudduth 10:25 AM ET August 20

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