Debby another lesson in understanding tropical cyclone hazards

Even as Debby continues to dump rain across portions of northern Florida today, there is a lesson to be learned from the event. That lesson is to understand that tropical storms and hurricanes have multiple weapons that can cause problems. It’s not just the big headline making wind and surge machines such as Katrina, Ike or Camille. Even a weak tropical storm, like Debby is now, can create huge disruptions in the lives of those who are in the path.

Let’s take a look back at TS Allison in 2001. It formed in June and moved up out of the western Gulf of Mexico and settled in over Houston, Texas. The result was around $5 billion in damage due to the 40+ inches of rain that fell across the region. Allison is the only tropical storm to have its name retired from the 6 year list of names. Yet, for Allison, there was no mass evacuation like we saw ahead of category 5 Rita in 2005 or category 2 Ike in 2008. People usually do not flee a 60 mph tropical storm. Instead, the millions of people who live in and around Houston were treated to days of torturous rain and flooding. It was an epic nightmare and one that will never be forgotten.

Tropical cyclones produce heavy rain as a means to disperse the heat that builds up in the tropics. It’s that simple. As I mentioned in a previous post, that rain is a function of the storm’s heat engine doing its thing. It’s just unfortunate that us humans happen to live where these rains can pose serious issues for us.

Debby has dumped in excess of 20 inches of rain over parts of the Florida Panhandle. Sink holes are opening up, parts of I-10 are closed due to flooding and life for many people is simply miserable today. Yet, this was no hurricane. It did not have the “scary” 130 mph winds that would get a lot of attention. It did not push a 20 foot storm surge towards the coast. Yet what Debby has done still managed to cause a lot of grief for a lot of people. There’s no avoiding it, you can’t move your house out of the way of the relentless rain. Evacuating is only necessary if flood waters get too high. So what can be done?

My point is that people all along the coast and then a couple of hundred miles inland need to realize that tropical cyclones are more than just wind and surge producers. First and foremost they are rain makers. Too much water in too little time always equals problems. And, as we have seen time and again, too much rain over a long period of time is just as bad. So as we progress through the hurricane season, remember that all tropical cyclones are capable of inflicting damage and causing loss of life. The degree to which the various effects manifest themselves depends on many variables. This is why it is important to not focus on the hype of “a hurricane might be coming” but rather think of it as “there is a dangerous weather event that could possibly¬† change my life forever”. Then, prepare accordingly.

As for the future of Debby? It should cross Florida in the coming days and finally move faster out in to the open waters of the Atlantic. Let’s hope it does as Debby has more than left its mark on Florida.

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Debby going to be a forecast challenge

The latest computer model guidance regarding tropical storm Debby has not helped to paint a clearer picture of where the storm, forecast to be a hurricane, will eventually make landfall. In fact, this could be one of the more complicated storms to deal with in quite some time.

Currently, Debby is experiencing some shear which means the upper level winds are blowing across the top of the storm from a certain direction rather than fanning out in all directions. The shear is keeping the storm from being able to align itself vertically and the deepest convection is displaced well away from the center of circulation. This shear is forecast to relax but as mentioned in the latest NHC discussion, it is not a guarantee, so Debby may have some intensity issues over the next few days. It is important to note that intensity forecasting is where the least amount of skill lies and significant changes up or down are possible. The latest forecast maintains the notion that Debby will become a hurricane as it turns west across the warm Gulf of Mexico.

The track forecast is turning out to be quite difficult. What was once a fairly straight forward forecast that Debby would turn west under a developing ridge of high pressure has turned in to a potential huge change coming up. The NHC mentions the ECMWF model which has shown Debby moving west and even south of west towards Texas for the last several days now has the storm making landfall in Louisiana in about three days. As I mentioned, this is a big change from previous runs and we’ll have to see what happens with each subsequent run. In other words, is this the beginning of a trend of just a temporary “goof” by the model and it will get back on its “west” idea soon. We’ll have to wait and see. Track forecasting is sometimes quite easy, this time, it looks to be just opposite.

HPC 3 Day Precip Forecast

HPC 3 Day Precip Forecast

Let’s talk about rain fall. Taking a look at the HPC’s precip forecast for the next three days, we can plainly see that Debby has a tremendous amount of moisture to dump along its path. The Florida peninsula through the central Gulf Coast could receive several inches of rain as Debby moves quite slowly, allowing the rain fall totals to pile up. This is not to be taken lightly. Fresh water flooding from excessive rains generated by tropical cyclones is a leading killer. Often times flooded roads are accessed by people who think that they can navigate the waters. This is a dangerous idea and I urge people to be mindful of the potential flooding impact from the rain. I would like to point out that you can use weather.gov for a wealth of information regarding your local conditions. Just type in your ZIP Code and the landing page will likely contain all sorts of locally based watch/warning info, hurricane local statements and more. This info is for your area, not a national broad brush forecast. Remember: weather.gov

I am currently in Georgia after wrapping up a project I had with CNN to launch a weather balloon and its payload to high altitude yesterday morning. The prep and launch were spectacular, I cannot wait to show you the video of that. The ascent went very well and we were able to track the payload using APRS. I will post a separate blog about this project later tomorrow, complete with some video of the launch. I’ll also talk about what went wrong and why we were not able to recover a majority of the payload after the balloon burst.

Once I return home from GA later today, I’ll begin preparing equipment for a trip to the Gulf Coast to provide on-scene coverage and info as Debby passes by or perhaps makes a direct impact on the region. I’ll lay out my plans tomorrow as a lot will hinge on what the forecast track is and how strong Debby gets. Meanwhile, everyone along the Gulf Coast should keep close tabs on the latest forecast info from the NHC and your local NWS. I’ll have another post here tonight with frequent updates on Twitter.

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Gulf system slow to develop, not sure where it is headed

As you know, 96L is being closely monitored for developments as it slowly moves out of the Caribbean Sea and in to the southern Gulf of Mexico. This morning’s satellite pictures reveal very deep convection associated with the system but it still lacks sufficient organization to be classified as a depression. That being said, the NHC continues to note that pressures are falling in the region while upper level winds are forecast to become more conducive for development.

Hopefully the Hurricane Hunters will fly in to the region today and provide much more data on what the structure and overall organization is with 96L.

The future track and intensity will depend a lot on where a solid low level center develops and how quickly the system strengthens. It is interesting to point out that the SHIPS intensity model indicates a moderate tropical storm and not a hurricane. This is obviously good news especially when we also consider that the usually aggressive GFDL and HWRF intensity models both show a very weak system. This can change and probably will as the low takes shape and gets better organized. At least for the time being, we’re not looking at a potential hurricane – let’s hope it stays that way.

As for where this system will end up? It’s too tough to call right now. Some of the model guidance suggests a track in to the central Gulf of Mexico with a turn back to the west and even south of west towards Texas/Mexico. Other models keep the would-be storm heading towards the northeast portion of the Gulf, with possible impacts in Florida. Right now, everyone along the Gulf Coast should just keep an eye on what goes on with 96L today and tomorrow. It’s not moving very fast and there will be plenty of time to react and prepare if needed.

I am on the road today and tomorrow but will post updates regularly. Fortunately, the rest of the tropics remain nice and quiet.

 

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Global models indicating chance for tropical cyclone formation in the Gulf of Mexico

The NHC has outlined an area of disturbed weather that is situated in the southeast Gulf of Mexico. Right now, it is broad and disorganized and upper level winds are simply too strong to support additional development. However, this could change over the next few days and this just might lead to the development of at least a tropical depression if not a named storm (the next one would be Debby).

Water temps in the Gulf are plenty warm with ample heat content to support tropical storm formation. I think the question will come down to how much the upper level winds calm down to allow for the divergence aloft needed to promote deep convection or thunderstorm activity. Since we do not have a low level center to track or for the models to latch on to, it’s difficult to determine what might eventually happen with this system. The bottom line is that it is likely going to be a slowly developing storm that has potential for impacting the weather over some portion of the Gulf Coast next week. Stay tuned.

The rest of the tropics are nice and quiet even as TS Chris spins away in the northern latitudes. It remains only an interest to shipping.

I’ll post another update here tonight and will discuss the Gulf system further during my appearance on the Barometer Bob Internet show. I’ll be calling in around 8:15 ET tonight. You may listen in here: Barometer Bob Show

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Tropics a little more active today

The tropics are getting to be more active as we head towards the end of the month. Tropical storm Chris formed yesterday despite being over the cooler waters of the North Atlantic. Chris is only a concern to shipping interests and even that impact is minor since the storm is small and obviously not intense.

Now I am keeping an eye on the disturbance in the waters around Cuba and Florida for possible development later this weekend. Several of the global computer models indicate that a more defined area of low pressure will form from this mess somewhere in the central Gulf of Mexico. It should then get pulled eastward towards Florida as a strong trough sweeps in over the eastern United States. At the very least, it looks like more rain is in store for Florida (the peninsula anyway) over the next several days. It is also possible that a tropical depression or weak tropical storm could form from this system though that is not currently forecast by the National Hurricane Center. Right now, their outlook indicates only a 20% chance of development. Remember, this only goes out to 48 hours. I am thinking that beyond that time, over the weekend, that we’ll see a more organized system develop in the open Gulf. For now, it’s something to keep tabs on as I do not see any indications that we’ll get much more than a weak tropical storm, mainly a rain maker, out of this system.

In the east Pacific, 95-E is weakening due to several negative factors that will not allow for it to develop. The remainder of the east Pacific is finally free and clear of any development potential. I’ll post another update on the system in the Gulf/Caribbean this evening.

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