Copious amount of moisture for parts of Southeast but no development seen with 92L

Radar image showing the large amount of rain across portions of the Southeast

Radar image showing the large amount of rain across portions of the Southeast

There is an awful lot of rain spreading across portions of the Southeast this morning but it’s not associated with the disturbance in the Gulf of Mexico – at least not directly.

Looking at satellite imagery, it is easy to tell that 92L has not become any better organized over night. The energy is not focusing around the weak low pressure center and continues to be spread out. As long as this continues, the system will not develop.

The pattern we’ve seen in place across the Southeast for the past several days will persist through the weekend with a change finally coming early next week. The front hung up across the area will fade and a return to a more typical summertime pattern will ensue. However, all of the rain that has fallen and that is still coming presents a problem to consider for later on: what if we get a tropical storm or hurricane landfall in this area over the next few weeks? I am concerned about the flood risk for the Southeast should a tropical cyclone pay a visit. So far, there’s not been any risk of that since Alberto back in June. We are coming up on the peak time of the season and there is a lot of talk in the hurricane forecasting world of a busy period coming up as the overall pattern seems to be heading towards one more conducive for development. We’ve seen a lot of rain across a good deal of the Southeast this summer. Rivers will be swollen and the ground saturated. Let’s hope this is not a set-up to a major flood event as we progress through the peak of the season.

In the east Atlantic, Erin remains a weak tropical storm as it fights the dry air still in place. This is not much of a surprise and I think it won’t be too much longer until we see the dry air ease up and the real meat of the season kicks in. In fact, another strong tropical wave is emerging from the coast of Africa now with potential for development over the next several days. At least for now, there are no threats for land areas to worry about.

I’ll post another update this evening concerning 92L and the rest of the tropics.

M. Sudduth 8:57am ET August 17

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92L has the spin but lacks the organized convection

Vorticity chart showing the spin (red blob) associated with 92L in the Gulf of Mexico

Vorticity chart showing the spin (red blob) associated with 92L in the Gulf of Mexico

A quick post about 92L this evening. As you can see by the 850mb vorticity map that I have included here, the system has the spin or vorticity that it needs to thrive. What’s lacking is organized deep convection wrapping around this spin. Without the convection wrapping around the center of circulation, which is clearly seen in satellite imagery, the low pressure area will remain fairly weak.

The shear values are not too strong but apparently are just strong enough to displace the main area of showers and thunderstorms off to the east and north of the center. Until and unless this shear lets up more, 92L won’t develop much despite sitting over very warm Gulf of Mexico water.

Computer guidance points towards Texas or northern Mexico but this is for the center. The worst weather, for now at least, is located well away from the center. It’s possible that Texas could see some beneficial rain from this system but how much and where is tough to say right now. The low should move steadily off to the west or west-northwest over the weekend.

We’ll see what the NHC says about this feature tonight and then see how it looks tomorrow morning. The Hurricane Hunters can get out there fairly quickly if need be should things look more interesting in the morning. For now, it’s something to watch but poses no major threat of impact over the weekend.

I’ll post more here in the morning.

M. Sudduth 4:35pm ET August 16

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Erin Now a Depression, Gulf System Disorganized

As of 11:00AM this morning, most of the deep thunderstorm activity with what is now Tropical Depression Erin has vanished.  The culprit is dry air sitting over the majority of the tropical Atlantic, which has essentially put a lid on convective development – much like throwing a glass of cold water in a boiling pot of water.  Here’s a water vapor image, showing what is left of Erin and the stable environment out in front of the former tropical storm:

Tropical Storm Erin and the Atlantic

Tropical Depression Erin (pink arrow) and the dry environment ahead as seen in Water Vapor imagery

 

Meanwhile, closer to home, a low level swirl has emerged into the southwest Gulf of Mexico.  This is what is left of the tropical system we’ve been watching over the last few days.  Again, dry air and strong upper level winds have created an unfavorable environment for development in the Gulf, even though a distinct low-level swirl can be seen in visible satellite imagery:

Visible image of 92L in the Gulf

Tropical disturbance in the Gulf of Mexico as of Friday morning. Note the low level swirl, free of thunderstorm activity.

 

As long as the environment continues to be hostile like this, it will be very difficult for either system to get better organized.  However, since the Gulf system is close to land – it will continue to be monitored for signs of development over the next few days, and recon is standing by to fly into the system if necessary.

Looking forward a few days, the large-scale environment is about to change across the tropical Atlantic.  A large-scale atmospheric wave called the MJO (or, Madden-Julian Oscillation), is expected to move into a phase which will enhance upward motion in the Atlantic next week.  Generally speaking, this creates an environment with less dry-air, lower surface pressures and more shower and thunderstorm activity across the deep tropics.

As noted in the latest update from Colorado State University, it is possible we will see one or more systems develop in the second half of August as we quickly approach the peak of the Atlantic hurricane season.

M. Watkins – Friday, 12:31PM EDT 8/16/2013

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Two high potential areas for development in the Atlantic Basin

Tropical weather outlook map showiong 92L and 93L

Tropical weather outlook map showiong 92L and 93L

The NHC has outlined two areas, 92L and 93L, for potentially becoming the next tropical depression in the Atlantic Basin this evening. Neither pose a significant threat of impact to land for the time being.

Looking at satellite images of 92L, which is located in the western Caribbean Sea, the organization trend appears to be continuing. It won’t take much to get this system to tropical depression status. The NHC reports that winds are already gusting to gale force within the heavy rain bands to the east of the broad center of circulation. The main impact here will be rain and occasional gusty winds for portions of the Caymans, western Cuba and the Yucatan.

So far, the advanced global models are not impressed with 92L and do little with it over the coming days. On the other hand, some of the regional, hurricane-specific models create a hurricane out of the system. This seems unlikely considering the nature of the upper level winds across the Gulf of Mexico as we round out the week. However, water temps are very warm across the region and intensity forecasting is the weak link in the overall hurricane forecasting process. Odds are this system remains weak and lopsided, with most of the worst weather to the east of the center. We shall see.

As far as track goes, here again, the models are of little help since the global models do not show much of anything to begin with. A track generally northwest and eventually over the Yucatan seems likely tomorrow and Friday. Beyond that time, we’ll see what’s out there before worrying too much about where it goes.

In the far eastern Atlantic, 93L continues to become better organized and should become a tropical depression before the weekend. Its track seems to be westward over the open Atlantic with no impact to land except for portions of the Cape Verde Islands. We’ll have plenty of time to monitor this system as it moves westward.

I’ll post more here tomorrow morning on both systems.

M. Sudduth 8:05pm ET August 14

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92L in the Caribbean likely to bring a lot of rain to Yucatan as tropics begin to ramp up

Computer model plots for 92L courtesy of Hurricane Analytics

Computer model plots for 92L courtesy of Hurricane Analytics

Invest area 92L is looking more organized today with deep convection taking on a more curved look in satellite imagery. Also noted is a more well established upper level outflow pattern. This will aid in the development of this system over the next couple of days while conditions remain favorable over the very warm waters of the Caribbean Sea.

The NHC notes that a low pressure center may be forming somewhere between the Caymans and the Yucatan. The low is forecast by most of the computer models to move to the northwest and possibly cross the Yucatan and in to the Gulf of Mexico. This means that a lot of rain and some increase in wind is headed for the region today and tomorrow. Interests in the area need to be aware of this large weather system and understand the rain threat is significant. Fortunately, it does not look like 92L will have much chance to rapidly strengthen but it wouldn’t take much for it to become a tropical depression or tropical storm.

Beyond the next 48 hours, the track is quite uncertain. Some of the model guidance indicates a track towards the U.S. Gulf Coast while others are more west towards Mexico. As we have seen so many times before, it will come down to the timing of how an upper level trough interacts with the system over the coming days.

If the trough can create a weakness in the steering pattern to the north of the disturbance, then it can have a hole, if you will, to move in to and thus towards the Gulf Coast states.

On the other hand, if the trough is not strong enough to erode the high pressure to the north of the disturbance, and the high actually builds back in once the trough lifts out, then it will get pushed westward across the Bay of Campeche and towards Mexico. There’s no way to know which scenario will play out – we’ll just have to wait and see. Right now, most of the reliable guidance is pointing towards the Gulf Coast but this can change as more data becomes available for each new run of the models. If you live along the U.S. Gulf Coast anywhere from Texas to Florida, just keep an eye on this feature over the next couple of days. As I said, intensity forecasts from the various models do not indicate much chance for strengthening and hopefully that will remain the case. We’ll watch and see how things progress today and tomorrow.

Elsewhere, we have invest area 93L far out in the eastern Atlantic. This system has a solid chance of becoming a tropical depression before it moves in to a more stable environment where the mid-level air is drier. It’s only of concern to interests in the Cape Verde Islands right now.

All of this activity is part of the pattern that is slowly beginning to unfold across the tropics. We’ve seen a lot of storm activity in the Pacific, now it’s the Atlantic’s turn. The next several weeks are likely to become increasingly busy throughout the Atlantic as there are signs that the upper level pattern is about to become quite favorable. Despite all the talk of dry air, dust and a lack of activity, it is still going to be a very busy season. There are just too many overwhelming signals in favor of that to be ignored. Now is the time to be prepared. Take that generator to a small engine repair shop to have it looked at in case you need it later. Do the little things now that can help alleviate the stress that comes with an approaching hurricane. It’s about to get very busy out there and as such, people need to be ready.

I’ll have another post here later on this evening.

M. Sudduth 1pm ET August 14

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