Tropical depression 9 forms, forecast to become strong hurricane in the Caribbean Sea

Tropical Depression Nine

Tropical Depression Nine

Well it took a bit of time but the tropical wave that we have been watching for the last several days has strengthened to TD #9. It is currently situated well east of the Leeward Islands but will close in rather quickly, bringing tropical storm conditions to the region within 36 hours.

The depression is currently winning the battle against the unusually dry air that has been in place all hurricane season across the deep tropics. Now that it is moving across ocean heat content that is considerably higher than in recent days, the amount of energy needed to fuel the deep convection is in place. Keep in mind that sea surface temperatures and heat content only increase ahead of the soon-to-be storm (which will be Isaac).

Interests in the Leewards need to be ready for a strengthening tropical storm and a large one at that. This means squally weather, heavy rains and winds gusting to near hurricane force in less than 48 hours.

Once past the Lesser Antilles, what would presumably be Isaac is forecast by the NHC to pass south of Puerto Rico and just clip portions of Hispaniola as it heads to a position just south of Cuba in five days. Now this part is extremely important. If the cyclone remains far enough south of these land masses, it could strengthen quite a bit. On the other hand, if the delicate circulation gets tangled up within the mountains of the Greater Antilles, it would almost certainly result in a weaker, disrupted storm/hurricane. The next few days will be critical in terms of what happens next.

I know it is natural to want to know what happens after the five day forecast period. There are certainly plenty of sites that have long range models available. Let’s just say that interests in Florida and indeed the Southeast U.S. as a whole need to watch the progress of this developing system very closely. There are some indications in the long range guidance that it could end up in the eastern Gulf of Mexico while other models suggest a path east of Florida. So there is the problem. It’s just too far out to even worry about right now. My best advice is to monitor and be ready to act. You should already have a hurricane plan in place for just such an event. If not, you better be ready, if not for this one, then for the rest of the season ahead.

We will have a lot more information in the coming days as recon planes from NOAA and the Air Force will be checking the system out thoroughly. This information will help to make the forecasts even better and will give us all the detail we need to prepare accordingly.

I would also like to remind our readers that we do have an app in the App Store that is available for purchase. It is a great way to keep up with the latest from HurricaneTrack.com on your iPhone, iPod Touch or even iPad. The app features this blog, our Twitter posts, Facebook updates, live weather data during landfall missions (might we have one coming up soon?), live web cam images from our own instrumented wind towers, video blogs EXCLUSIVE to our app and even a GPS tracking map to show our location while we are out in the field! To get it now click here. If what is a shoe-in to become Isaac makes landfall in the U.S., our app will literally take you there like nothing you have ever seen in a mobile app! It’s a great way to support our work while getting something innovative and informative in return.

I’ll post another update here later this afternoon. Keep in mind that our private clients who have not logged in this season that we do have our LIVE video briefing at 2pm ET on the Client Services site.

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Gulf free of tropical troubles for now as we wait for 94L to develop

The Hurricane Hunters investigated 95L off the coast of Mexico in the western Gulf and found basically nothing. Winds were light and the system is losing organization. It appears that any chance of tropical storm formation is quickly dwindling. However, the overall pattern is somewhat unsettled across the region and periods of squally weather will persist across the region for a few more days.

Meanwhile, 94L continues to struggle to put up any deep thunderstorms. The dry air mass is simply too overpowering right now. It is interesting to note that the global models seem to want to ramp this system up after it passes through the Lesser Antilles. While I do not see anything intense coming out of the models just yet, it is possible that 94L will wait and wait and wait until it reaches the Caribbean Sea before developing. And the weaker it remains, the more west it will track. Some of the longer range models forecast the slowly developing system to move up towards Florida via the Greater Antilles first. This means that it could get tangled up in the high terrain of Haiti and Cuba if in fact it takes the track. So any threat to Florida should be considered minimal right now. I just don’t see this developing much over the next day or two. After that, we’ll see. The season has just been so hostile for deep tropical development that for it to all of a sudden change would be a surprise to me. This is why we have to just watch and see what happens. So far, there is nothing to indicate a major problem coming up for the Lesser Antilles or beyond. If that changes, we will still have plenty of time to react accordingly.

I’ll have more here tomorrow morning.

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Tropics look busy but it’s all bark so far

Tropical Weather Outlook Map

Tropical Weather Outlook Map

Taking a look at the latest Tropical Weather Outlook map from the National Hurricane Center, one might think that things were really busy. In one sense, things are busy, with plenty of suspect areas to monitor. On the other hand, with the exception of Gordon, which passed through portions of the Azores as a hurricane, looks can be somewhat deceiving as there is nothing brewing right now that poses any significant threat to land areas.

As I mentioned, Gordon moved through the Azores last night as a hurricane and continues to move eastward where it will weaken over cooler waters, falling short of affecting Portugal.

The system that has the most attention right now within the hurricane blogosphere is 94L. It still lacks any deep convection and is surrounded by an awful lot of dry air which has been the calling card of the deep tropics this season. Neither the GFS or the ECMWF strengthen it much as it passes through the Lesser Antilles and in to the eastern Caribbean. It is also worth noting that the GFDL and HWRF both keep it weak as well. Granted, the statistical SHIP model does make 94L a hurricane but it has not done so well with intensity this season, so I discount that for now.

I think the environment is just too hostile right now, mainly the lack of deep moisture and resulting absence of vertical instability. This is a major factor and even though wind shear is light and we’re in the latter part of August, if the atmosphere is too dry, convection cannot commence and sustain and the entire process will never really get a good start. So until and unless we see a change in the thermodynamics of 94L’s surroundings, it will likely be a weak area of low pressure as it moves westward. I would think that we will begin to see an increase in convection as it moves towards higher ocean heat content in a day or so. Keep in mind too that 94L has a large envelope of energy that it has to bundle and focus around a common area of low pressure. In other words, it has a lot of work to do before becoming much of an issue for anyone. This is good news and for now, it should stay that way.

Elsewhere, 95L is along the eastern Mexican coast and poses little more than a rain threat for portions of Mexico. I doubt it will ever get back out over water enough to amount to anything and none of the reliable models indicate much happening.

Then we have 96L out near Africa. All I can say is read back about 94L and there you go. Anything coming out of the deep tropics so far has struggled and I see no reason why that will change anytime soon. Obviously, it bears watching as it tracks steadily westward but I would not worry about it for at least a week.

I’ll cover all of these areas and more on today’s video blog which will be posted to the HurricaneTrack iPhone app this afternoon. Then, I’ll have another blog post here early this evening, sooner if need be.

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Watching 94L closely – key will be convection and how soon it begins to pop

Notice the Lack of Convection with 94L Yet Out Ahead of it, Deeper Convection is Blossoming

Notice the Lack of Convection with 94L Yet Out Ahead of it, Deeper Convection is Blossoming

Convection is what drives tropical cyclones. Without that constant upward motion that lifts air high in to the atmosphere, with the resulting thunderstorms, then they fizzle out. Dry air is a quick killer of convection and right now, 94L is still dealing with fighting off the dry air. However, I think that may change soon.

Look at the satellite picture in this post. Notice the deeper convection out ahead of 94L as indicated by the yellow arrows. Instead of more dry air and barren ocean with no convection out in front, we see some fairly deep thunderstorm activity and this is where 94L is headed. So it stands to reason, perhaps, that within a day or so, the system will begin to take advantage of more favorable conditions and begin to ramp up. This will also coincide with it moving in to warmer ocean heat content near and past 50 W longitude. So watch for this sign…if the convection is slow in coming or pulses up and down, the 94L will struggle for a while. If it is able to grow and maintain deep convection, then it will likely be off to the races and people in the Lesser Antilles will need to be monitoring closely.

I’ll have more here tomorrow morning.

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Gordon about to pass through southern Azores as western Gulf and 94L keep things interesting

Hurricane Gordon Approaching the Azores

Hurricane Gordon Approaching the Azores

Hurricane Gordon is headed for the southern Azores Islands and is beginning to weaken as shear and cooler water begins to impact the circulation. This process will likely continue and should bring Gordon to under hurricane intensity as it tracks through the region over the next day or so. After that time, a more rapid weakening is probable and Gordon will be just a remnant low pressure area.

In the western Gulf, we have the left over energy associated with what was once TS Helene trying to flare up again over the very warm water. A substantial increase in convection is noted this afternoon and we’ll have to see if the NHC outlines it for any kind of potential for re-development. I do not see anything significant in the major computer models, just pulses of weak low pressure areas moving northeast out of this general area of disturbed weather. We also have a cold front entering the northern Gulf and this will add to the piling up of tropical moisture across the region, resulting in fairly unsettled weather as we start the week. While it’s possible that we could see some development in the western Gulf, I doubt that it would be anything to worry about as it would likely stay weak.

Next we have 94L which has been quite interesting to watch over the last few days. It seems that there is a big of cat and mouse going on with the global models, especially the GFS. At first, that model was indicating quite a significant hurricane developing and impacting the eastern Caribbean. Then, within just a few forecast cycles, the model kind of said, “Oops, never mind” and keeps 94L very weak as it approaches the Lesser Antilles. However, the SHIPS and LGEM intensity models both make 94L a powerful hurricane, contrary to what the global models indicate, including the ECMWF which has never really done much with 94L.

Heat Content Map- Notice Increase Between 50 and 60 W

Heat Content Map- Notice Increase Between 50 and 60 W

In this case, I think we need to go by what we see. Looking at 94L right now, it is definitely not organizing or developing much. Convection is weak and limited although it has a noticeable circulation and a large envelope of moisture to work with. I think that it is reasonable to expect that as it moves westward towards higher ocean heat content, between 50 and 60 west longitude, that we can expect to see it begin to strengthen. The overall lack of development in the deep tropics this season is apparently not going to be easily overcome and this, so far, spells good news for the islands.

In the longer term, the track of 94L depends largely on its strength. A shallower, less intense system will tend to track more west. On the other hand, if it develops deep convection and starts to increase its size in the atmosphere, it will feel the deeper layers of the steering pattern better and could gain more latitude over time. This all boils down to weak = track through the Caribbean while strong = track likely north of the Caribbean. Stay tuned, there’s no easy answer for what will happen with this system.

I’ll cover the very latest on all of the goings on in the tropics on today’s video blog which will be posted to our iPhone app later this afternoon. If you have the app, remember to completely close it and then open it again to refresh the video blogs page. This was a flaw that will be fixed during the first update coming out soon that will allow you to pull down and refresh the video page. For now, simply closing the app completely and restarting it will refresh everything.

I’ll post another update here this evening as well.

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