Mixed signals mean low confidence forecast for TD9

I am going to address TD9 in this blog post and will cover the other activity around the Atlantic and what is going on in the Pacific in my video discussion to be posted early this afternoon. With all of the interest in what happens with TD9 and its potential impact to Florida, I figure I would tackle that first.

Some deep convection has developed with TD9 in the region around wetern Cuba and just south of the island. Whether or not this is the start of a strengthening trend remains to be seen. Click for full size image.

Some deep convection has developed with TD9 in the region around wetern Cuba and just south of the island. Whether or not this is the start of a strengthening trend remains to be seen. Click for full size image.

During the overnight hours, deep thunderstorms began to develop in association with the depression in the vicinity of western Cuba and even to the south of the island. It is not clear just yet if this convection is near the low level circulation center or if perhaps that center has reformed closer to the thunderstorm activity. We will know more as morning visible satellite images come in and recon flies in to the system later today.

For now, the NHC is classifying it as a tropical depression with winds of 35 mph. The forecast is very uncertain due to a variety of mixed signals in the overall pattern for the days ahead.

Normally, a tropical depression over the Gulf of Mexico this time of year would be concerning. While it is somewhat concerning this time around, the limiting factors are fairly substantial.

First of all, strong winds blowing across the top of the depression from north to south are likely keeping the convection removed from the low level center. This is extremely important to the health of the depression and until the shear relaxes, assuming it ever does, we won’t see much strengthening.

Most of the models that do develop the depression in to a tropical storm or a hurricane do so in a couple of days – not in the immediate future. So we have some time to watch and see how the upper level pattern evolves over the eastern Gulf of Mexico. With water temps in the upper 80s in most areas of the Gulf, it won’t take much to allow the system to ramp up quickly.

The other issue is dry mid level air that would need to be mixed out in order for more efficient convection to take place. Dry air is a stable environment and tends to limit the amount of thunderstorms a tropical cyclone can produce. It is not clear whether or not the dry air will remain a limiting factor. Here too, if it abates and the low can generate deep thunderstorms, it’s only a matter of time before it starts intensifying.

Track forecast model plots showing a fairly tight clustering of the models in the Big Bend area of Florida. This could change over the next few days.

Track forecast model plots showing a fairly tight clustering of the models in the Big Bend area of Florida. This could change over the next few days. Click for full size image.

The track forecast is also tricky since we are talking about several days out for one and secondly, Florida’s western coastline is shaped that changes in the course of the would-be storm will have potentially huge impacts on who feels what effects.

For now, the official forecast calls for the center to pass in to the Big Bend area of Florida, in the northeast Gulf of Mexico. This is concerning to me because the region is very prone to storm surge, even from “weak storms”. Obviously a hurricane would be worse but even moderate tropical storm winds can push several feet of water onshore within portions of the Big Bend region.

The next area of concern is Tampa Bay. While most of the model guidance suggests a track farther north, we need to watch this closely since this area is also very susceptible to storm surge from even minor tropical storms.

It appears that it will all come down to the mid level trough that is forecast to come in and erode the strong high pressure area that steered the depression in to the Gulf in the first place. At some point, it will round the western edge of the high and begin turning more north then northeast. When and where this happens will determine what part of Florida receives the most substantial impacts. Obviously the intensity will come in to play at that point as well. It’s still just too soon to know with any degree of confidence – something we have grown accustom to dealing with concerning this system.

For now, I think that the biggest impact will be heavy rain and the possibility of storm surge flooding along the coast. It goes without saying that if the depression becomes a hurricane, those impacts are elevated quite a bit. We’re going to have to wait it out and see what happens with the upper environment over the next few days. The NHC makes it very clear in their forecast that the intensity portion especially is of low confidence. Sometimes that’s just the way it goes.

As I said, I will have a full video discussion posted here by early this afternoon. I will go over the very latest on TD9 plus what to expect as we watch TD8 off the North Carolina coast. Meanwhile, Hawaii is watching TS Madeline and hurricane Lester very closely as both could bring impacts to the region later this week. I will also discuss the coming week to 10 days and what to look for as we head in to September.

M. Sudduth 8:20 AM ET Aug 29



No real concern about 99L any longer as we focus on other areas over the coming days

Atlantic tropical weather outlook map from the NHC showing the areas of interest and the current position of TS Gaston

Atlantic tropical weather outlook map from the NHC showing the areas of interest and the current position of TS Gaston

Wanted to post some thoughts on 99L this very late hour of Friday night/early Saturday morning. It’s been a long week and tonight I can sleep soundly and not wonder what the future model output will show for the storm that never was.

I also want to comment on the other areas that bear watching as we progress through the weekend. One thing is fairly clear to me: there are no hurricane threats looming so we have that going for us.

As it turned out, the environment just didn’t support the development of the tropical wave that garnered so much attention this past week. Invest area 99L as it become widely known as will just pass in to the Gulf of Mexico from the Florida Straits this weekend with little more than passing squalls. While I can’t say development chances are zero, in my opinion, the chance of this becoming a hurricane is as close to zero as one could ask for. It’s just not going to happen this time. Despite the HWRF model blowing it up run after run in to a formidable hurricane, upper level conditions and the lack of overall organization of the system should keep this a scenario only inside of the computer model’s world.

Now we have a couple of other areas to watch – one in the Gulf of Mexico, the other not far from Bermuda over the Atlantic. Neither system look to develop much in the coming days – part of the overall negative pattern we seem to be in right now. Even TS Gaston is struggling as of late but it is forecast by most of the global model guidance to bust through the shear and other limiting factors to finally become a classic open Atlantic hurricane. It too poses no threat to land and I don’t see it ever becoming an issue except for an increase in ocean swells depending on how strong it gets and how far west it tracks.

East Pacific tropical storm Madeline is one to watch if you live in or are planning a trip to Hawaii for next week

East Pacific tropical storm Madeline is one to watch if you live in or are planning a trip to Hawaii for next week

In the east Pacific, tropical storm Madeline is forecast to strengthen and become a hurricane as it moves in the general direction of Hawaii next week. Water temps in the region are running a little above normal so it’s possible that Madeline could make it to Hawaii as a tropical storm. It’s tough as heck to hit the Big Island from the east so we’ll see how this pans out. There is plenty of time to monitor the situation and react as needed as we know more about the track and intensity of this Pacific tropical storm.

Last but not least, I will be watching with keen interest as a new tropical wave emerges from Africa early next week. The GFS in particular has been very consistent in developing it right away and moving west for quite a while. The steering pattern that the GFS has been showing is one that could keep what ever might develop moving along just south of 20N latitude for several days at least. That being said, I do not see this being a threat to the Lesser Antilles, not in the modeling anyway. It’s early and it’s prime time for the Atlantic hurricane season and we know how quickly things can change. This next system will be something to keep an eye assuming the modeling is correct and it does in fact develop. Time will tell.

That’s it for now, time for some deep sleep and then more posts coming over the weekend.

M. Sudduth 12:35 AM ET Aug 27


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


End of the road coming up for Erika? More like hitting a brick wall…

It has been a tough few days for hurricane forecasters and not because of something like Katrina 10 years ago. This time, it has been because the storm in question, Erika, has been such a pain in the neck to forecast. Fortunately, any deviations from the ideas set out by the National Hurricane Center, then echoed by others (including me), have been positives in terms of overall impact. In other words, Erika has not lived up to expectations and that is a good thing.

Before I get in to the (likely short) future of Erika, let’s not forget what happened around this time yesterday. Copious amounts of rain fell as deep convection developed right over Dominica in the eastern Caribbean Sea. This led to the unfortunate loss of life and terrifying flash flooding in the mountainous terrain of the island. Please let this be a reminder that even a tropical storm can be lethal. So much emphasis is placed on wind speed and pressure and category that the general public loses sight of the overall idea that we are talking about a destructive weather phenomenon. Rain is absolutely an impact from tropical cyclones as the people of Dominica were painfully reminded of yesterday.

So what does the future hold for Erika and any potential impacts to the United States? The answer to that question is rooted within what happens during the next 24 hours or so.

Satellite photo showing the poorly organized structure of TS Erika as it approaches Hispaniola

Satellite photo showing the poorly organized structure of TS Erika as it approaches Hispaniola

Erika is poorly organized but does have a fairly large envelope of energy. Tropical storm conditions are mainly being felt to the east of the center of circulation which itself is located just to the southeast of the Dominican Republic. In fact, you can see in the satellite photo that a burst of convection has popped up right near that center, giving Erika a little longer before the brick wall.

The United States and even Cuba for that matter owes a great deal of its hurricane protection to the island of Hispaniola. It’s all a matter of luck and geography but the fact remains that without Hispaniola in the way, many more powerful hurricanes would have lashed Florida, Cuba and eventually other locations along the western Atlantic Basin. This comes with a price though. The high terrain of the island literally wrings out the moisture from passing tropical storms and hurricanes. The resultant flash floods and mudslides can produce appalling loss of life and mind-boggling damage. Erika is headed right for the island and will slam in to it – likely bringing very heavy rain to the region.

As the storm traverses the rugged terrain, the low level center will almost certainly dissipate and we will be left with a trough of low pressure that was formerly Erika. Now, there’s a chance that the tenacious storm will just dance across and emerge in to the Florida Straits ready to go. I wouldn’t bet on that happening but you never, ever turn your back on a tropical anything coming through water that is near 90 degrees F! The next day or so is the key. If there is anything left of Erika once it passes over Hispaniola, then Florida might have to deal with a tropical storm and maybe, just maybe, a hurricane. So much will depend on how much warm water it has to work with and what the upper level winds are like. For now, Erika is headed for the Caribbean Road Block otherwise known as Hispaniola. What happens after that is beyond my ability to figure out – it’s a wait and see deal, nothing more.

Meanwhile, in the Pacific, hurricane Ignacio continues to track northwest in the general direction of Hawaii. The five day forecast keeps the center north of the island chain but we know how that can go. Obviously, interest out that way should keep watching and be ready to act should the track shift south even by a little bit. Water temperatures in the east Pacific, especially the northern Pacific, are quite a bit warmer than normal. So far, Hawaii has escaped major calamity this season – we’ll see if that luck holds.

I’ll have a video discussion on Erika and other happenings in the tropics, including a look back at Katrina 10 years ago today, posted later this afternoon.

M. Sudduth 8:55 AM ET August 28


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