Isaac proving to be tough to forecast

NOAA G-IV Jet

NOAA G-IV Jet

The NOAA G-IV jet flew what is called a synoptic mission yesterday in the environment well out ahead of Isaac to sample the atmosphere. The data collected was input in to the various global computer models to help narrow down the forecast track. In some ways, it seems to have helped, in others, not so much. And as if to add to the challenges already present, Isaac veers off the forecast track some overnight- steering more west than predicted.

All in all, the general idea of an eventual Gulf Coast landfall is still the solution of the major global computer models. Exactly where and when remains to be seen as well as to what extent the Florida peninsula will be impacted.

Right now, Isaac is still rather poorly organized. For what ever reason, its central core just can’t get aligned vertically. Instead, it is meandering around a larger envelope of low pressure. Sure there are numerous areas of deep convection seen in satellite imagery, but Isaac is still struggling. It is noteworthy though that the central pressure is now down to 1000 mb, so in that regard, it has strengthened a little.

Latest Track Map from the NHC

Latest Track Map from the NHC

The very latest from the NHC shows a track over Haiti, eastern Cuba and then the western most Florida Keys over the next three days or so. After that time, Isaac has a clear shot over the open Gulf to approach the coast, seemingly along the Panhandle. We know the five day position has a significant error factor and that the position will certainly change over the weekend and in to early next week. One key element of tonight’s computer models is the ECMWF which has stopped its westward forecast showing a landfall in Louisiana to a forecast coming much more in line with the U.S. generated GFS model. In fact, the two models are in remarkable good agreement – probably a result of the upper air data that was added recently from the G-IV mission. I know a lot of people along the central Gulf Coast from Mississippi west were getting quite concerned as each forecast seemed to increase the threat from Isaac. I do not know if we are seeing a honing in of the true landfall location now or not, there is still too much that can change over the next 120 hours or more. People anywhere from the peninsula of Florida to New Orleans need to keep tabs on Isaac and be ready to take action if needed.

As for intensity? Who knows? This part of Isaac’s forecast over the last few days has been the toughest challenge for the NHC. As I mentioned, without a well defined inner core, Isaac stands little chance to intensify before moving over the rugged terrain that lies ahead. Nevertheless, it will dump a lot of rain on that land and flooding will be a major concern. Isaac is also a large tropical storm with a huge wind field. This will mean a longer period of time that tropical storm conditions will persist for any land areas that Isaac impacts. Remember, it’s not just around the center that the winds are strong. The outer bands contain heavy rain and strong winds too and these will affect Florida sometime over the weekend. I cannot say it enough times: tropical cyclones are not just wind machines, they have rain, storm surge and the possibility of tornadoes and downburst winds. Not to mention the rough surf that accompanies any tropical system, no matter how weak or strong. A storm of this size commands respect, especially if it ever suddenly begins to strengthen.

So if you live in Florida, anywhere in Florida, you should be watching Isaac closely this weekend. The Keys will be the first to feel the effects as will southeast Florida. A lot of people live down there in Dade and Broward counties. The rain bands will wreak havoc on traffic so be careful out there. Once the weather goes down hill, just stay off the roads and monitor conditions from home. Hopefully you have the needed supplies in case the power is lost and as long as Isaac does not make landfall in southeast Florida, the effects will be in and out and things can go back to normal early next week. Of course, we will then have to focus on a potential landfall along the Panhandle. With so many days still left until that would happen, we are still in a wait and see situation for now but people in that region should be ready to act if Isaac does in fact come your way.

The rest of the tropics are a non-issue right now. TS Joyce all but completely sheared out yesterday and may never recover. Then, invest area 97L in the far eastern Atlantic is certainly worth watching but not a concern at this time.

I’ll have today’s video blog posted to the HurricaneTrack app early this afternoon after the 11am NHC advisory package comes out. I’ll also post an update here at that time as well and will begin talking about our landfall mission plans for next week.

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Isaac not half the storm it could be, literally, but that could change

Satellite Shot of Disorganized Isaac

Satellite Shot of Disorganized Isaac

Taking a look at the most recent satellite shot of Issac reveals that it is almost like half of a tropical storm tonight. The western side seems more “rounded” than does the east and this is a sign that the storm is still struggling. While this may be good news in terms of a strong hurricane heading towards land, it does not mean that Isaac is without dangerous weapons.

The very warm Caribbean Sea will continue to provide ample energy for the large clusters of rain and thunderstorms that Isaac is currently pushing up around its circulation. This rain can cause severe flooding in places like Hispaniola and Cuba as the storm approaches. So why is it struggling so much? I am not sure but it seems to be the norm this season until some boiling point appears to be reached and BANG! off goes the lid. Will Isaac follow that pattern and suddenly intensify? Not until it develops a solid inner core. Think of it as having a perfectly align spine in your body. Get that spine out of alignment and all kinds of ailments ensue. The same holds true for tropical cyclones. The low level center must line up with the mid and upper level centers in order for the process of the storm/hurricane to run at peak levels. Isaac is no where near that right now and that is great news – so far.

I’ll have a new, much longer blog post tomorrow morning after we get a look at the overnight model guidance. Obviously, the shift to the west is of concern for portions of the Gulf Coast and I will go over any new changes tomorrow morning.

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Isaac weak now but has potential for significant strengthening as it keeps Florida and Gulf Coast on edge

Track map showing Isaac and Joyce

Track map showing Isaac and Joyce

Issac has been an under-performer so far and no one is complaining about that. The storm simply has not been able to “pull it together” and bundle all of the heat energy that it has been trying to tap for the last several days. Perhaps it never will but in case it finally comes together, people in its path need to be prepared. I am not talking about only Florida either, we first have to deal with Isaac’s impact on the Greater Antilles.

The current forecast track takes Isaac over Hispaniola and eastern Cuba where the rugged terrain will literally squeeze the moisture out of the storm, dumping excessive rain fall in a short amount of time. The flooding risk, especially in Haiti, will be substantial, even if Isaac remains a “weak” tropical storm. People in the region generally know this about tropical cyclones but each one poses a new challenge as to the track and intensity and how much rain actually falls. There is no doubt that freshwater flooding from tropical cyclones is a big problem and Isaac is likely to be no exception.

Right now, the storm is still trying to organize and once it does, it could intensify quickly over the very warm water of the Caribbean Sea. It has yet to develop a solid inner core as we saw last night with the fact that the center itself reformed entirely in a different location. Isaac is also a large storm with tropical storm force winds extending out from the center up to 140 miles. I think that once the inner core develops, Isaac will become a formidable hurricane. But the question is, when? When does this happen? If it happens soon, then the effects to  the Greater Antilles will be amplified. If it happens after Isaac passes over the islands, then the worst of it would be felt in Florida perhaps. Sadly, intensity forecasting is where the least amount of skill lies. So many factors are involved and modeling the inner core of a tropical cyclone is very difficult to do. Sudden changes, up or down, in wind speed often take place in hurricanes and tropical storms. With Isaac, it has been a slow, steady process all along. We just don’t know when or if that pace will pick up.

The track forecast is also a problem as it places a good deal of Florida under the threat of hurricane conditions. Right now, the current forecast track takes Isaac over a significant portion of eastern Cuba before emerging over the southeast Gulf of Mexico. Assuming that the storm does not get torn up completely, it has a chance over the high heat content waters of the Florida Straits to intensify rapidly. This means that the Florida Keys may have to deal with an intensifying hurricane passing through. It’s just so hard to know what will actually happen as so much depends on exactly how much time Isaac spends over Cuba.

Since Isaac has such a large wind field, it will affect a huge area of Florida. Even inland counties will have tropical storm force winds to deal with. And, Florida’s peninsula would be on the right-hand side of the circulation, usually the more active side of a hurricane. Flooding could be a problem with the constant barrage of rain bands that will move through, well ahead of the center. It has been seven years since any hurricane has affected Florida directly. I hope that people take this seriously. Even a weak storm can bring tremendous amounts of rain and as we saw with Fay in 2008, rain alone is enough to cause some serious grief. The time to begin preparing for Isaac’s impacts is now. Don’t wait to see what the final outcome may be. By then, you’ll be really stressed and have to deal with all of the other people who waited. Believe me, you don’t want that.

ECMWF 5 Day Forecast for Isaac

ECMWF 5 Day Forecast for Isaac

Obviously, the big question is where does Isaac make landfall, its final landfall that is? The NHC forecast track suggests that it is possible Isaac heads for the Florida panhandle by day five and six. Yet, if we look at the ECMWF model, it still shows Isaac swinging out farther to the west before turning more north. The GFS model, on the other hand, has Isaac closer to the peninsula all along. Either way, the possibility of an eastern Gulf of Mexico landfall seems to be increasing and let me tell you, if Isaac gets strong, storm surge in that area is a

GFS 5 Day Forecast for Isaac

GFS 5 Day Forecast for Isaac

big concern. We’ll deal with that later, no need to worry about something that may not come to pass just yet but the potential is certainly there, especially for areas to the east of where Isaac makes landfall.

I will cover all of these details and more in today’s Hurricane Outlook and Discussion that will be posted to our iPhone app shortly. I will also discuss the possibilities for our field work and how the app will help to keep you informed as we work in the landfall zone to bring you the latest information, video posts and live weather data. This is where our app will really shine and make a name for itself. I’ll have  a separate blog post about the app later this afternoon. In the meantime, I’ll have occasional updates here and on Twitter and our Facebook page. If you have any questions, please feel free to send an email or ask via one of our social media outlets. I’ll do my best to answer.

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Isaac getting stronger as it nears the Lesser Antilles as new depression forming in east Atlantic

TS Isaac Aimed at Greater Antilles and Florida

TS Isaac Aimed at Greater Antilles and Florida

The deep convection has really blossomed over the center of Isaac in recent hours. This is a sign that the stronger upper level winds are relaxing and that the dry mid-level air is being eroded away. Now, a much more unstable air mass is being tapped and Isaac is poised to strengthen, possibly to hurricane intensity.

As I mentioned in my last post, if we saw a burst of sustained deep convection, this could mean a rather rough day for the islands as Isaac passes through. The intense rain squalls that occur underneath such strong convection drag the winds down to the surface quite efficiently. I know from experience and the only good news here is that Isaac is not doing this as a major hurricane right now. So the next 24 hours or so will be quite tumultuous for portions of the Lesser Antilles and I hope people there are prepared and take it seriously. There is nothing quite like an intensifying tropical cyclone, no matter its initial strength. You can keep track of Issac’s progression through the region via Meteo France radar out of Guadeloupe by clicking here.

Once Isaac passes in to the eastern Caribbean, it is forecast to strengthen in to a hurricane. Just how strong it gets is up for debate. So many factors can shape the intensity of these systems that it is impossible to know for sure just how strong Issac will get. It would seem that with increasing ocean heat content and an apparently very favorable environment, that Isaac has the potential to become a strong hurricane before reaching Hispaniola. And that is a key milestone for the system and what eventually happens along the U.S. coastline.

The latest forecast from the NHC shows a track that would take Isaac over a good deal of the islands of Hispaniola and then eastern Cuba. If this does in fact happen, I would have to think that the rugged terrain would do quite a number on the circulation of Isaac and weaken it substantially. There are times when hurricanes have hit these land masses and never had time to fully recover. While this is great for interests further along in the forecast track, it would be terrible news for people on those islands. The threat of heavy rains and mudslides alone is enough to cause great concern. However, the geography is just right so that often times, the Greater Antilles have been the saving grace for many potentially deadly U.S. hurricane landfalls. Will that be the case again? I wish I knew. Let’s look at two models for some compare and contrast info.

First, the GFS. It has been doing pretty well this season and seems to have a good run to run handle on Isaac. It shows the system moving towards a break in the large high pressure area situated over the western Atlantic. This break or weakness would turn Isaac WNW and then NW at a point that would take it over the islands and possibly disrupt the circulation quite a bit. Obviously, the less land Isaac encounters, the less this disruption will impact the would-be hurricane.

5 Day ECMWF Model Showing Isaac South of Cuba

5 Day ECMWF Model Showing Isaac South of Cuba

On the other hand, the often praised for its superior forecast skill ECMWF model or Euro shows a weaker Isaac moving more west with time. It misses the big islands and turns Isaac in to the Gulf of Mexico as a formidable hurricane. In fact, the most recent run of the Euro was the western most forecast for Isaac yet, putting in to Louisiana in 10 days. I think we will have to watch and see one key element here. Does Isaac remain weak and get pushed along more by the lower level flow than it would if it were a deeper, larger storm in the atmosphere? Right now, it’s definitely growing in size in all directions. So unless it has issues getting stronger and extending up in to the atmosphere, I think the Euro can be discounted for now. Thus a threat to Florida, after Isaac passes over Hispaniola and Cuba, is a real possibility.

The other scenario would be that the turn NW happens even sooner and Isaac crosses Hispaniola rather quickly with no land interaction in Cuba after that. This would pose a threat farther up the coast of Florida and possibly even the Carolinas. This cannot be ruled out – remember Irene last year?

Today will be about the Lesser Antilles and what impact Isaac has there. Once it clears the islands, we can focus more on possible landfall solutions down the road. There is a considerable amount of time still left for Isaac to track in a number of directions and be at a variety of intensities. The best course of action for people in Florida is to just be on alert, check your generators, make sure you can put your hurricane plan in to action if needed. Just do the things now that can help make things a little less stressful should Isaac come your way. It has been seven years since any hurricane has hit Florida. A lot of people have no hurricane experience at all. Isaac might break the drought but it might not, we will just have to wait and see as hard as that may seem.

Meanwhile, invest area 96L out in the eastern Atlantic continues to become better organized. It should become a tropical depression later today and eventually TS Joyce as it moves westward across the deep tropics. There is no cause for alarm with this system just yet. Let’s deal with Isaac right now before worrying too much about a future storm. The east Pacific is nice and quiet.

 

 

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Isaac’s first impact will be to the Lesser Antilles but to what extent?

TS Isaac With Some Deep Convection Tonight

TS Isaac With Some Deep Convection Tonight

TS Isaac is making news headlines and for good reason. While plenty of people are looking down the road, several days in fact, let’s not forget what’s in store for people in the Lesser Antilles over the next day or so.

While Isaac may be fairly weak right now, it could intensify rather quickly and if it does so while passing over the islands, it could mean a day of rather rough conditions. What I will be looking for is to see if very deep convection forms and takes the shape of a ball. This would tell me that a CDO or central dense overcast area of intense thunderstorm activity has developed. It is underneath these intense cores of copious rain fall that the strongest winds usually occur. If we see Isaac pushing up deep convection, then look out below as strong gusts of wind will likely result. This is why people in the warning area need to be prepared. It is impossible to forecast these convective bursts and we can only monitor via satellite and perhaps local radar where available. It’s just something to keep in mind since the Lesser Antilles are first in line to deal with Isaac.

As for later issues? We’ll have to take it one day at a time and see what happens as Isaac moves in to the Caribbean Sea. We’ve been through this enough times to know that there are no clear cut answers this far out. Different sets of models will show different results at different times of each day. For now, let’s see what happens as the storm passes through the Lesser Antilles. Hopefully it won’t be much but in case Isaac suddenly ramps up, people need to be prepared.

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