Texas deluge as tropical moisture aimed at Lone Star State

NHC graphical outlook and the potential track area of invest 91L

NHC graphical outlook and the potential track area of invest 91L

A lot has been made already about the presence of invest area 91L. After all, it is hurricane season and we do have an area of interest to monitor in a region that hasn’t had much activity over the past few years. In fact, a grand total of zero hurricanes have made landfall in Texas since 2008 – Ike was the last. While there is nothing at all to suggest that 91L will become a hurricane, it does raise a few eyebrows and for good reason: the rain threat.

May was an absolutely stunning month for rain in parts of Texas. Houston alone set records and had flooding issues. Farther inland, areas such as Austin, San Antonio and Wimberley experienced flooding which resulted in loss of life and significant damage. The power of water is often unappreciated until it changes lives and alters the landscape.

Enter 91L in to the picture and the NHC’s potential track area as seen in the graphic and you can see why Texans are probably a little more concerned about this system than they might be otherwise. None of the intensity guidance suggests anything more than a lopsided, weak tropical storm. Nothing to worry about, right? Wrong. Tropical cyclones, this includes tropical depressions and tropical storms mind you, have four main hazards that they can hit you with: wind, storm surge, rain and tornadoes (downburst winds too). The majority of the public responds well when the forecast suggests 150 mph winds are coming. Sadly, storm surge, as lethal as it is, seems to be ignored (see Katrina, Ike and Sandy).

That leaves us with rain, the most abundant of the tropical cyclone hazards and yet it is the most ignored and least understood by the average person. We think of rain as cleansing and necessary to sustain life. However, too much of it at once or even over several days has a drastic effect on life as we know it.

Only a few inches of rain in a short period of time can overwhelm flood control systems in large metro areas such as Houston. If the rain keeps coming, everything literally cascades in to a total disaster, often stranding hundreds of people who didn’t seem to know better. Even after years of “turn around, don’t drown” people will think they are immune to the laws of physics and do something that defies logic. All because they didn’t respect the power of rain and freshwater flooding.

What does all of this have to do with 91L? Plenty. I think this is an opportunity for people in the region, mainly Texas, to show that they have learned from past experiences. Allison in 2001 was quite a while ago, I’ll give them that. But the May floods were, well, in May – just a few short weeks ago.

There is the potential for what ever becomes of 91L, whether or not it attains tropical storm intensity, to drop a lot of rain over areas that simply don’t need it – at least not in the quantities that some forecasts are showing.

The good news is that upper level winds should keep 91L from becoming much more than a rain threat. This will minimize the amount of wind and surge impact to the coast. However, any onshore flow in areas such as Bolivar Peninsula could lead to over wash – that area is flat with little to no dune protection.

The bad news is that the Gulf of Mexico is ripe with moisture. Water temps are running above normal with actual temps close to the upper 80s along parts of the northwest Gulf. This will lead to an incredible amount of precipitable water being lifted in to the atmosphere and wrung out over Texas next week. Flooding is almost a certainty but exactly where is impossible to pinpoint.

It is going to be important for people in the region to monitor their local news outlets and reliable social media sources for updates. This is going to be a constantly changing situation and a lot will come down to how much rain falls over a certain area and for how long. Since that cannot be forecast with any real accuracy this far out, keeping up with the latest from the National Weather Service and your local TV meteorologists will be important in keeping you and your family safe.

I highly recommend using weather.gov and then inputting your ZIP Code. The return page will have a ton of useful links and information, including the latest watch/warning package and any special statements. It’s all right there at your fingertips – use it!

TS Carlos tracking map from the National Hurricane Center

TS Carlos tracking map from the National Hurricane Center

Meanwhile, Carlos is a tropical storm now just off the coast of Mexico in the eastern Pacific. The forecast takes the storm inland between Tuesday and Wednesday while strengthening it again to hurricane strength. Again, as with 91L in the Gulf of Mexico, the biggest issue with Carlos will be the potential for flooding rain. Certainly hurricane force winds are an issue but with a slow moving tropical system the rain is probably the larger concern at this point. Fortunately, the proximity of Carlos to land should keep it from intensifying much more than it is now, fluctuating back and forth between tropical storm and hurricane strength. Once inland in a few days, its moisture will spread over the interior portions of Mexico further extending the rain and flooding threat to that region.

I will have continuing coverage of 91L and Carlos tomorrow and via my video blog discussions now available through our YouTube channel. Follow and subscribe to the channel here: HurricaneTrack YouTube channel

M. Sudduth 12:15 PM ET June 14

 

Critical week ahead for parts of the Southeast

Computer guidance has shifted west over night, resulting in a track that poses a threat to the Carolinas later this week

Computer guidance has shifted west over night, resulting in a track that poses a threat to the Carolinas later this week

This week is probably one of the worst weeks out of the entire year that a potential hurricane could threaten the United States. It’s coming up on Independence Day and a huge monkey wrench is likely to be thrown in to the plans of thousands who are wanting to relax at the beach. While nothing is etched in stone, far from it, the chances seem to be going up that something rather unpleasant is in the making as we move through this all-important week.

The issue is, of course, 91L and what will very likely become TS Arthur. The NHC continues to indicate a high chance of development over the next few days.

As of early this morning, the area of low pressure was situated to the east of Florida, about the same latitude as Melbourne and vicinity. So far, organized deep convection remains limited. It appears that northerly winds are continuing to blow over the circulation, injecting some dry air while keeping a lid on tropical thunderstorm formation. However, all indications are that this pattern will change and we will have a tropical depression before too long.

At this point, the forecast guidance is in pretty good agreement that a tropical storm will form and move northward, actually somewhat west of north for a time. Then, the crucial turn to the northeast will commence ahead of an approaching trough swinging down from the upper Midwest. This acts like a soccer player kicking the ball (Arthur to be) out to sea. Well, it’s more complicated than that, but in keeping with current sports news, I thought the soccer analogy worked. The idea is that the supposed-storm would be pushed out to sea at some point – when this happens is very important.

The overnight runs of most of the models indicate that there is a good chance that the system could move over parts of extreme eastern North Carolina. To be fair, there is also a good chance the center remains just offshore. However, we should all know by now that the center is not the only area to watch – effects can reach out 50 to 100 miles or more from the center. We’re talking rip currents, bands of heavy rain, increasing winds and seas and the possibility of tropical storm or even hurricane winds affecting some part of the North Carolina coast. I do not say this without backing it up. The SHIPS intensity model, often cited in NHC advisories, brings the system to hurricane strength – so this needs to be considered. Add to the complication the fact that intensity forecasting is where the least amount of skill lies. Do not gamble on this being a weak, sheared storm with little to worry about. There is enough room for error that I would not be at all surprised to see this system become a hurricane.

For now, we have a slowly developing tropical cyclone just off the Florida coastline. That region will be the first to feel impacts. Higher surf, rain bands and an increase in wind will likely put a damper on vacationers along the east coast of the Sunshine state for a day or two. After that, we need to wait and see what develops and take it from there.

People along the Southeast coast are generally hurricane savvy. The one thing that concerns me is the crowds of people coming in to the region from some inland state and thus having zero hurricane experience. While I may be jumping too far ahead, this is something to consider since we are coming up on a massive beach holiday. This is not going to be “fun” or “exciting”, not in a good way. If what could be the season’s first storm and/or hurricane comes close enough to the coast, people need to be ready or the results could be very rough to deal with.

I will post another update on this developing situation later in the afternoon. I’ll also have the daily video blog posted to our app, Hurricane Impact, by 4pm ET. Follow along with the app which is available for iOS devices and Android. Simply search Hurricane Impact and stay connected where ever you are.

M. Sudduth 8 AM ET June 30

The pattern is the key

Trough (shaded in red) is the key in steering the potential tropical storm as we progress through the week ahead

Trough (shaded in red) is the key in steering the potential tropical storm as we progress through the week ahead

We will have to wait and see how the steering pattern in the atmosphere evolves before we know what will happen with what is probably going to be the first tropical storm of the season. Before we get in to that in more detail, let’s look at what we know for sure.

First of all, what does “91L” mean? This is the designation given to a system that is in the development stage. The numbers 90-99 plus the letter “L” for Atlantic are used to signify an area of interest before it becomes a tropical depression or stronger. It helps with computer models, recon, satellite assets, etc. Once we get to 99L, we start over with 90L and so on. Got it? Ok, let’s move on.

As of early this afternoon, 91L continues to deal with some dry air to the north that is limiting its ability to push up deep, tropical thunderstorms. The process of convection is what helps to lower the air pressure and start the chain reaction going to spin up a tropical cyclone. The NHC mentions that it may not be until Wednesday before conditions truly allow for development.

So far, the weak low has moved southward to about the latitude of Jacksonville, Florida. We may see it begin to push westward some early in the week before it turns north again ahead of an approaching trough in the atmosphere. This trough is the key to where what will probably be TS Arthur ends up.

To put it in simple terms, if the trough is not fast enough or strong enough, then the would-be storm could track more north than east. This would mean a track closer to the North Carolina coast later this week. It is also possible that the trough swings by and misses the system completely- not likely, but not impossible.

The latest computer guidance suggests that the pattern will be just right to kick the system out to the northeast enough to keep it away from the coast, minimizing impacts to places like the Outer Banks. However, we are talking about four to five days or more in to the future and even the slightest changes in the pattern could lead to some serious forecast challenges.

What about intensity? This is almost impossible to speculate on right now. We do not even have a tropical depression yet so I do not feel comfortable pretending to know how strong this system could get. The obvious signs are there: warm water, more favorable conditions, etc. but this tells me nothing about how well organized the storm would be later in the week. Let’s wait for it to develop and go from there. I think we all know by now how tough intensity forecasting is, no need to spend time worrying about that at this point in time.

I realize that this potential threat comes at perhaps the most critical time of the year for beach interests. Hard to believe we’re looking at a possible tropical storm threat for the Fourth of July along the Southeast coast. For this reason, I think it is especially important to be aware of the impacts that this system will bring. A lot of people will be heading to the beach in the coming days from the Carolinas to Georgia, Florida and on up the rest of the East Coast. Even the lesser-talked about impacts such as rip currents and ocean swells need to be addressed. Careful explanation of the hazards is important so that people are not afraid to keep their plans but are aware of things such as rip currents or large, breaking waves.

I will keep posting updates here at least once per day. I’ll also have frequent posts on Twitter and our Facebook page. Social media is a great tool to utilize for weather information. This blog, as well as Twitter and FB posts, all feed in to our iOS/Android app, Hurricane Impact. I also add a daily, detailed video discussion exclusive to the app. It’s a great way to stay connected even if you’re on the go. Search Hurricane Impact in the App Store or on Google Play. I’ll have more here tomorrow morning around 9am ET.

M. Sudduth 1:40 PM ET June 29

Invest area 91L poised to develop but do so slowly

Satellite photo showing a slowly organizing area of low pressure just off the Carolina coast

Satellite photo showing a slowly organizing area of low pressure just off the Carolina coast

The NHC continues to increase the chances that the low pressure area off the Southeast coast will develop in to a tropical cyclone. This means it could become a least a tropical depression and probably a tropical storm.

Latest computer model guidance suggests that a slow process will continue as the low moves generally south and somewhat west of south over the next few days. Fortunately, the heavy weather will remain offshore but this has obvious implications for any boating interests and small craft especially should be aware of this developing situation.

An interesting run of the ECMWF model has generated quite the buzz on the hurricane social media circuit. It seems that the 12Z run was quite enthusiastic on developing 91L in to a moderate to strong tropical storm next week. We cannot worry about one run of any one model but it is noted and we’ll see if subsequent model guidance concurs and sets up a trend.

For now, folks from the Carolinas south to Florida should just keep an eye on the system. With quite a busy week coming up, people will be distracted and thus using social media, hurricane-related apps (we have one called Hurricane Impact), as well as television and radio will keep you informed without overwhelming you with info.

In the eastern Pacific, yet another tropical depression has formed but is forecast to move away from Mexico as it steadily develops in to a tropical storm. It poses no threat to land at this time.

I’ll have more here tomorrow in the early afternoon.

M. Sudduth 8:39 PM ET June 28