More going on in the tropics than we’ve seen in quite some time

It’s the end of August and the tropics are busy. We have a pair of hurricanes that are headed towards Hawaii, one in the Atlantic that poses no threat to land, two disorganized depressions and one significant tropical wave that has just emerged off of Africa. Did I miss anything? I think that’s it. So let’s look at each area beginning in the central Pacific…

Hurricane Madeline

Hurricane Madeline track forecast from the Central Pacific Hurricane Center

Hurricane Madeline track forecast from the Central Pacific Hurricane Center. Click for full size.

Just a couple of days ago the forecast for Madeline did not indicate it would even reach hurricane strength. My how that changed – it is now a category four with winds of 130 mph. It is currently moving west but is expected to track a little south of west over the next day or so and this just might keep the core of the worst weather south of Hawaii where a hurricane watch is currently in effect for the Big Island.

The official forecast brings the center fairly close and the Big Island would be within the right-front quadrant of the hurricane as it passes by. This is usually the stronger side of a hurricane relative to its forward movement and as such, it is possible that hurricane conditions could be experienced throughout portions the region. In addition, dangerously high waves along with very heavy rain could cause localized damage. Hawaii is a unique geographic location for hurricanes to impact and so pinpointing the effects is hard to do; so much depends on the eventual track and intensity. Needless to say, residents and visitors on the Big Island need to be preparing for a hurricane today and tomorrow in anticipation of Madeline’s arrival or close passage sometime on Thursday.

Hurricane Lester

Meanwhile, off to the east of Madeline is hurricane Lester with winds of 125 mph, down from a peak of 140 yesterday.

The good news here is that Lester is currently forecast to track to the north of the islands over the next few days and should also weaken considerably while doing so. As such, I am not nearly as concerned about impacts from Lester as I am about Madeline for Hawaii.

There will be another increase in the swells and local high surf due to the intensity of Lester in recent days. While the surfers in Hawaii can take advantage of this, novice swimmers should avoid tangling with the big waves headed to the area.

Satellite photo showing hurricane Gaston, TD8 and TD9

Satellite photo showing hurricane Gaston, TD8 and TD9

Hurricane Gaston

Moving along in to the Atlantic where hurricane Gaston has weakened some overnight. Top winds here are 100 mph but there is a large eye apparent on satellite imagery. It is possible that the hurricane could strengthen again over the fairly warm waters of the subtropical Atlantic. Gaston is only an issue for shipping lanes as it will likely turn northeast out over the open water with an increase in forward speed.

TD8

Tropical depression 8, just off the North Carolina coast, is trying to wrap deep thunderstorms around its well defined center of circulation this morning. It won’t take much for it to strengthen over the very warm water and become a tropical storm. If it does so before TD9 does, it would be named Hermine.

The effects overall will be minimal with a few passing rain bands and locally gusty winds at times for the Outer Banks of North Carolina. Even the waves will not be too much of an issue since the wind is not very strong right now but locally higher surf is possible within any squalls that happen to make it to the coast.

The forecast is for the depression to possibly become a tropical storm and then turn north and eventually northeast and away from land.

TD9

The forecast for TD9 remains very complex which seems to have been the case ever since it was just an area of interest or tropical wave several days ago.

During the overnight hours, deep thunderstorms have managed to expand and possibly cover the low level center. If this is the case, it might be that we finally have a tropical storm out of this system. The Hurricane Hunters will be investigating the depression off and on today and we’ll know more later if it’s not obvious based on satellite that it has in fact strengthened.

Overall the idea of a Florida Big Bend area landfall on Thursday seems intact. The question is really more about how strong it manages to get before that time. Upper level winds are not particularly favorable but could be just enough so that the depression makes it to tropical storm intensity plus perhaps a little more strengthening after that.

I see two main impacts from this system that concern me. First, storm surge flooding along the immediate coast. The area of Florida that the system is forecast to move in to is very vulnerable to storm surge from tropical storms and hurricanes. The onshore flow, combined with the fact that the would-be storm will be pushing water in the direction that it is moving means several feet of inundation is possible. We won’t know how much is being predicted until later on and especially so when and if it becomes a tropical storm. Areas in the Big Bend region down to the Nature Coast should be prepared for some coastal storm surge issues on Thursday – this includes an increase in wave action as well along what is normally a very placid Gulf of Mexico.

Rainfall forecast over the next few days highlighting the chance for excessive rain totals in parts of Florida.

Rainfall forecast over the next few days highlighting the chance for excessive rain totals in parts of Florida.

The other significant impact will be the heavy rain. Several inches is likely to fall across portions of Florida and this will lead to areas of localized flooding. It’s impossible to pinpoint which areas will receive the most rain and when but it’s a good bet that north-central Florida will see rainfall totals exceeding 5 inches with isolated higher amounts.

I am not as concerned about the wind since the model guidance does not suggest a very high chance of this becoming a hurricane. However, the official forecast calls for 65 mph near landfall which is enough to knock down some trees and cause minor damage to property. Scattered power outages will also occur but it all depends on the final intensity near the time of landfall.

Once inland, the threat of heavy rain will spread in to southeast Georgia and northern Florida as the storm system moves towards the Atlantic. From there, things get very interesting. It is possible that we will see quite a ramping up of intensity once it gets out over the very warm water and begins moving off to the north and east. It is possible at that point that it could become a hurricane.

We will have to watch closely how the pattern evolves over the coming days as there is some hint in the models that the system could track fairly close to the coast as high pressure tries to build in across the western Atlantic again. If it gets blocked enough, it is not out of the question that another landfall or very close approach to the coast could take place farther north. This is something we can worry about later on but it is beginning to show up in some of the models so keep that in mind along the Mid-Atlantic states and points north. I’m not too concerned just yet but the trend has my attention.

I am planning to head down to Florida tomorrow to set up a couple of our unmanned cameras along the immediate coast. I will also have the ability to provide live wind and pressure data from the on-board weather station atop my Chevy Tahoe. I will not set out any additional weather stations for this event but will have a live stream coming from the vehicle so that I can relay instant wind readings as I record them on the anemometer.

I will outline not only the goings on in the tropics but also my plans for setting up the cameras along the Gulf Coast of Florida in anticipation of the landfall on Thursday during my video discussion which I will post early this afternoon. This will be followed by another blog post early this evening.

M. Sudduth 8:30 AM ET Aug 30

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Conflicting signals in the computer models for 99L

Visibile satellite image showing 99L (left) and TS Gaston (right). Click to view full size.

Visibile satellite image showing 99L (left) and TS Gaston (right). Click to view full size.

It has been a very interesting few days when it comes to what may or may not happen with invest area 99L. As of this morning, there are still no easy answers despite the apparent better organization of the tropical wave.

The NHC is indicating a 60% chance of further development over the next five days. As of this writing, there is currently a Hurricane Hunter crew heading out to investigate the system and that will help tremendously with a better understanding of the structure and local atmospheric conditions.

What has changed somewhat in the past day is the fact that one of the best performing global models, the ECMWF, has begun developing 99L in the vicinity of the Bahamas and sends it in to Florida. Other models have followed such as the U.S. generated HWRF which did very well last season with Joaquin – once it formed. I will not worry too much about the intensity indicated by the various computer guidance but it goes without saying that the very warm water temps that lie in the path of 99L make for a concerning few days ahead.

As I mentioned, the organization of the tropical wave appears to be improving. Deep thunderstorms or convection has blossomed and managed to stick around and even expand in size as of late. This could be a sign that it will finally begin to form a low level circulation and slowly start its ramp up in intensity. The Hurricane Hunter crew will be able to observe that and relay that information to the NHC almost immediately.

Recent computer model projections for invest area 99L. The track could potentially bring heavy rain and gusty winds to portions of the NE Caribbean and the southeast Bahamas

Recent computer model projections for invest area 99L. The track could potentially bring heavy rain and gusty winds to portions of the NE Caribbean and the southeast Bahamas

With all of this being said, let’s talk about short-term impacts. As it looks now, 99L will move towards the extreme northeast Caribbean Sea later today and tomorrow. This will result in periods of squally weather for portions of the northern Leeward Islands, spreading west towards Puerto Rico and maybe Hispaniola. Heavy rain and gusty winds are to be expected with some areas receiving more than others depending on the actual track and how well organized it becomes. Flash flooding is a concern for any mountainous terrain of the Caribbean islands that the tropical wave interacts with.

Next up will be the southeast Bahamas. The same scenario holds true here – periods of heavy rain, possibly bands of it if the system goes on to develop. Winds could increase more so than we will see in the Caribbean, it all depends on how quickly 99L can form a low level center – if at all. Needless to say, interests in the Bahamas should be paying close attention to the progress of this developing weather system.

It’s what happens later in the forecast period that has a lot of people quite interested, and rightfully so. The overnight models have shown a marked trend towards the west with time once the system reaches the northern Bahamas in about 4 to 5 days.

We all know by now what tends to happen with tropical cyclones when they turn west under a strong area of high pressure anchored over the Southeast U.S. It usually does not end well. Now, there is a fine line between being informative and discussing the pattern and trying to just get people anxious over potentially nothing. With social media, it is easy to spread graphics showing cat-4 and 5 hurricanes hitting some specific locale. I will not do that unless it is part of the official forecast. Right now, we don’t even have a tropical depression and there is no guarantee that we ever will.

If I live in Florida along the east coast especially, I am just going to pay closer attention to this system and be ready to act if need be. The one major downside to this NOT being named yet is that it might not command the attention and respect that it would if it were a tropical storm, for example. On the other hand, I think enough people are aware who would normally be that they won’t be caught off guard.

It’s been a long time, over 10 years, since a hurricane of any strength has made landfall in Florida. While there is a chance that streak ends sometime within the next 10 days, it is impossible to say for certain whether or not that comes to pass. It’s the heart of hurricane season. You live in Florida. You should be prepared every year as if it’s the year for your area to be hit. Beyond that, we will have to wait and see and let nature literally take its course. The data will be plentiful with recon missions planned from here on out. That will help to get a better handle on current conditions. From there, we can plan based on what happens as things evolve. It’s usually not easy and this situation seems to be no exception.

In the mean time, if you like watching harmless hurricanes roam the ocean, then Gaston is tailor-made for you. Right now, it is a tropical storm but is forecast to become a hurricane and last for days and days out over the open Atlantic. This will add to the seasonal ACE score in a big way, likely leading the way in making 2016 the busiest season in four years – pretty much as predicted by most groups that issue such forecasts.

In the eastern Pacific, the are two well organized disturbances that are both likely to go on to become tropical storms and eventually hurricanes. The good news: both are well away from Mexico and moving generally west with no impacts to land.

I will post my daily video discussion here later this afternoon followed by another blog post late tonight. Follow along as well in our app, Hurricane Impact, for blog updates, social media and video info right on your iOS device. Search Hurricane Impact in the App Store.

M. Sudduth 10:15 AM ET Aug 23

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