Bermuda could be impacted by Leslie as September looks to be quite busy due to lack of El Nino

Leslie Could Impact Bermuda This Weekend

Leslie Could Impact Bermuda This Weekend

TS Leslie developed some very deep convection over night with cloud tops reach an astonishing -88 degrees Celsius. Those cold cloud tops, however, did not wrap all the way around the center of the storm. This is due to the continuation of vertical wind shear which has been just enough to keep Leslie from strengthening much. I do think the burst of deep convection is a sign that Leslie will intensify given the right upper level conditions.

The current forecast track has not budged much from recent ones and it looks like a slow and steady course to the north-northwest throughout the week ahead makes the most sense considering the pattern. There will simply not be enough western Atlantic ridge to push Leslie back to the west enough to directly impact the U.S. That being said, I do believe that an increase in long period swells is coming – especially once Leslie becomes a hurricane. Its slow movement will allow for quite a build-up of energy in the ocean and this means a great surf weekend coming up for portions of the East Coast. It also means an increase in rip currents and as such, people heading to the beach need to be mindful of this hazard. We are still a few days away from the swells reaching the U.S. and I will address this again later in the week.

As for Bermuda, it looks as though Leslie could come fairly close to the island by the weekend as a strong hurricane. Some of the intensity models suggest that Leslie could approach or exceed category three intensity towards the end of the week. Interests in Bermuda need to pay close attention to the future track and strength of this storm. It also looks like Leslie will be quite large with an expanding wind field so even a brush with Bermuda could mean a period of high winds and very rough seas for the area.

Looking at the rest of the tropics, we have invest area 99L well out in the east-central Atlantic. It may develop some but is small in size and poses no threat to land areas.

In the eastern Pacific, TS John has formed to the southwest of the Baja peninsula and will move swiftly off to the northwest and not be a bother to Mexico.

SST Anomalies from August 3

SST Anomalies from August 3

Checking on the current state of the El Nino, we see that it has, in fact, backed off quite a bit in recent weeks. Comparing the SST anomaly maps from August 2 and the one from today, it is clear that the warming trend has stopped and even reversed in the eastern Pacific. This means that the threat of a significant El Nino event during the hurricane season is likely minimal at best. In other words, the negative conditions that a Pacific El Nino would typically bring to the Atlantic Basin are probably not going to be there.

SST Anomalies from September 3, Notice the Decrese in SST Temps in the East Pacific

SST Anomalies from September 3, Notice the Decrese in SST Temps in the East Pacific

The reason El Nino affects the Atlantic is similar to how a large hurricane, with its well established outflow, affects other tropical waves moving across the Atlantic. Remember TS Jean which formed east of Isaac? The large scale upward motion of Isaac led to strong outflow high in the atmosphere and this literally tore Jean apart and caused it to weaken and dissipate. An El Nino event, especially strong ones, causes tropical convection to persist across a good deal of the Pacific. This upward motion on a basin-wide scale acts to spread strong upper level winds across the deep tropics of the Atlantic, much like the outflow from a hurricane. This shear stops developing Atlantic systems in their tracks. Because we are not seeing a significant El Nino event taking shape right now, I suspect that September will be quite busy with a shift in activity more towards the Caribbean Sea and Gulf of Mexico. This is a natural evolution in any season when we see the tropical waves that come off of Africa lose their punch and the build up of low pressure in the western part of the Atlantic and Caribbean leads to development there.

The long range models, and we’re talking beyond 10 days here, indicate this pattern change is coming. Once Leslie moves out, we will probably only wait a few days, if that, before we have yet another named storm.

Curiously though, we have yet to have a major hurricane this season in the Atlantic. The layer of persistent dry air has really put a lid on things, literally. I think that Leslie has a chance to become a category three hurricane as it nears Bermuda as the global models indicate what looks like a favorable upper level wind pattern for it to develop. We may have had a lot of activity, but no intense hurricanes just yet.

I will go over a lot of what I have outlined here in today’s edition of the Hurricane Outlook and Discussion video for our iPhone app. I will also post an update here in the blog this evening to reflect the very latest on Leslie and whether or not I may be taking a trip to Bermuda later this week.

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Atlantic virtually dormant while east Pac keeps churning them out

Wow, things could not be much more quiet than they are now across the Atlantic Basin. I see no areas of significant convection that show any signs of development over the next few days. This certainly spells great news for coastal locations all over the Atlantic, Caribbean and the Gulf of Mexico. Now keep in mind that climatology suggests that it is towards the end of August and obviously through September that the tropics normally ramp up. We’ll see just how close to climatology we are as we move through the next few weeks. For now, enjoy the quiet.

In the east Pacific, the storms just keep coming off what seems like an assembly line. Right now, there is TS Hector which poses no threat to land and a new area of slowly organizing convection near the coast of Mexico that is destined to develop. This system (actually labeled as 95E) could run parallel to the Mexican coastline in the days ahead, bringing heavy rains and squally conditions to the region. We’ll have to watch it closely this week since it is already impacting land and could continue to do so. I’ll have more here tomorrow, including a look at the growing El Nino, SST anomalies and what the long range models are showing as we move in to the traditional heart of the hurricane season. I’ll also have an update on our iPhone app which has an update due out soon that will add new tracking maps and add some ease-of-use enhancements.

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Ernesto on its way to becoming a hurricane as it heads towards Belize

TS Ernesto over the Caribbean Sea

TS Ernesto over the Caribbean Sea

Conditions around Ernesto have improved and now the storm is really starting to ramp up. The main issue was dry mid-level air and the storm’s fast forward motion. It simply could not line itself up vertically and allow for the convective process that drives its heat engine to work efficiently.

Water temps are plenty warm and it is obvious by looking at satellite imagery that the outflow is well established now. Ernesto should become a hurricane before the day is out.

The threat to the U.S. is all but gone now and so the focus will be on Central America, specifically Belize.

As it looks now, Ernesto will be intensifying as it makes landfall. This is never good news. As I have written about before, it has been our experience in dealing with hurricanes in the field that when they hit while intensifying, their effects are amplified. This is due to the convection or upward motion of the clouds that act to bring the strong winds down to the surface. We noticed this most notably during hurricane Charley in 2004 and never forgot what it was like. While Ernesto is not expected to become as strong as Charley, I hope that folks in Belize realize that this is not going to be a weak, sheared and dried out tropical storm when it hits- not anymore. Wind damage could be a real issue with Ernesto along with the other hazards of coastal storm surge and torrential rains.

Farther up the Yucatan where Cancun and Cozumel are, the impacts will be far less. Since Ernesto is not an especially large storm, its effects will be confined to the areas south of the northeast tip of the Yucatan. There may very well be some passing squalls from the outer rain bands but I do not see any reason to believe that Ernesto will post any big problems for Cancun and vicinity. In fact, that area is only under a tropical storm watch at this time. If you have plans to visit the area, do not cancel as Ernesto is only a problem farther south.

Once the soon-to-be hurricane crosses the Yucatan, it could get buried over Central America and rain itself out. This will obviously have negative impacts on the region with excessive rainfall a possibility. The official track does take the storm back out over the extreme southern Bay of Campeche with a final landfall in Mexico near the end of the week. How much time Ernesto spends over land will likely determine how strong it can get once it reaches the water again, if it does not simply die out over land.

The rest of the tropical Atlantic is quiet for now. Florence has dissipated and will likely not be able to make any appreciable comeback. We’ll see, you never know in August.

In the east Pacific, the NHC is keeping tabs on invest area 92E which is forecast to become a tropical depression and eventually a hurricane by many of the intensity models .However, the steering pattern continues to favor a general westward track away from Mexico. This is not typical of an El Nino year and lends more evidence to the fact that the atmosphere is not behaving as if we were in El Nino conditions. With a fairly strong high pressure area over the eastern Pacific it is no wonder that recent hurricanes in the east-Pac have moved westward. It is also keeping the progress of the developing El Nino at a slow pace which could have implications on the Atlantic season from here on out. I’ll discuss that in more detail in tomorrow’s blog post.

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Busy times coming up for us as east Pac season begins tomorrow, we test our HURR-B and visit a NOAA Sentinel

East Pacific Season Begins Tomorrow

Tomorrow marks the beginning of the east Pacific hurricane season and it looks like it may begin right on cue with something to track. The NHC is currently monitoring investigation area 90-E (remember the reason by the numbers/letters? If not, I’ll have a refresher course tomorrow) well off the coast of Mexico and moving westward. It has an 80% chance of becoming a tropical depression but then upper level winds should become less favorable.

East Pacific TCHP Map (figure 1)

East Pacific TCHP Map (figure 1)

Computer models are in fairly good agreement on developing a more substantial tropical cyclone in the southeast Pacific over the next week to 10 days. There is in fact a large area of loosely organized convection several hundred miles south of El Salvador/Guatemala that is likely the disturbance that the models are picking up on. Water temps in the region are plenty warm with upper ocean heat content on the rise. This provides ample fuel for tropical storms and hurricanes (see figure 1). So do not be surprised if the east Pacific season gets off to a busy start. It’s too soon to know whether or not any development would affect coastal Mexico directly – I’ll post more on this as we progress through the week.

Next Week We Test HURR-B

I am very excited about our plans for next week. I will be joined by Greg Nordstrom from Mississippi State University as we set out to Texas where we will test our newly developed hurricane balloon. In case you are not familiar with this project, let me give you a quick overview. We have built a payload consisting of four GoPro Hero HD cameras and a pair of GPS recorders to send in to the eye of a hurricane via weather balloon. You might have seen “high altitude ballooning” becoming a more and more popular hobby with people putting their iPhones inside of a payload and sending it to the edge of space. We thought that it would be incredible to study the eye of a hurricane from the inside-up. So our plan is to deploy HURR-B (hurricane balloon) in to the eye and let it rise to 90,000 feet or higher where it will burst and fall back to the ground via parachute. We’ll locate it using satellite tracking and, if all goes well, will have perhaps some of the most stunning video of the inside of the eye of a hurricane that anyone has ever seen. But more than that, we’ll have the GPS data logged every second to tell us where HURR-B traveled and how fast. This will help to better understand the wind flow inside the eye and well above it. We hope that this will be the start of a long-term project where by we can gather data on landfalling hurricanes using weather balloons and increasingly sophisticated instrumentation to gather real time observations. We figured that it would be best to start simple to make sure this is even feasible.

Greg and I will meet in Atlanta next Monday and then head down to the Gulf Coast on Tuesday/Wednesday (more on this in the next section). We’ll arrive in Houston, TX Wednesday night and use Thursday to prep everything for the launch on Friday, May 25. We’ll launch twice- once to test everything to 25,000 feet and then another test to 90,000 feet or higher. We will stream the entire trip live on our public Ustream channel so be looking for that next Monday.

To raise the funding needed to make this possible, we have sold plastic tiles for people to sign their names using a Sharpie. The cost is $100 per tile and we then attach it to the outside of the payload to be sent to the edge of space. It’s a unique way to be a part of this innovative and important project. We only had 50 tiles available and have sold almost half so far. If you’re interested in purchasing one and being a part of our efforts, please see the HURR-B page here. I’ll post more on the progress of our testing throughout the week next week with plenty of pics and photos to follow.

NOAA Sentinel Visit to Test Remote Cam

NOAA Sentinel (figure 2)

NOAA Sentinel (figure 2)

While Greg and I are on this trip across the Gulf Coast to reach Texas, we figured we would stop in to visit the NOAA Sentinel in Mississippi. It is part of NOAA/CO-OPS’ Sentinels of the Coast program for capturing tide data during storm events (and of course during calm weather as well). We are partnering with NOAA to place one of our remotely operated Storm Surge cams high atop one of these 25 foot tall Sentinels (see figure 2) to stream live video on our Ustream channel during a hurricane or tropical storm. We have the opportunity to provide the public, media, emergency management and anyone else who is interested with unprecedented live video from the water, looking back at the coast. If we have another powerful hurricane strike near one of the many tide stations or the beefed-up Sentinels, we will work with NOAA to place one of the cams out well ahead of the worst conditions to stream live video but also to capture video which will help in better understand the impacts that storm surge and wind have along the immediate coast from a fixed camera position. We use a lot of time lapse in our research and this is an incredible opportunity to literally put a “watch dog” in the teeth of the hurricane, using technology to make it all possible while keeping our team as far away from the surge as possible. We will test the video feed next Wednesday for about an hour on our Ustream channel. I’ll post the times once we narrow it down with NOAA.

So as we approach the mid-way point in May, you can see that things are very busy for us. We also have our iPhone/Android app in development which I will discuss a great length in a couple of weeks. It will be a great way for you to keep up with the goings on in the tropics while providing live weather data and frequent video blogs during our field missions. More on all of that later on…. For now, we’ll watch the east Pacific for signs of getting started with its seasonal activity. While there are some rumblings, if you will, from some computer models about possible development in the Caribbean Sea, I’ll wait and see if that’s anything more than just a passing anomaly before posting much about it.

 

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How’s that La Niña going?

Subsurface Temps of the Tropical Pacific

Subsurface Temps of the Tropical Pacific

So far this winter, the La Niña that has been in place since last fall continues to hold strong. As the graphic from the Bureau of Meteorology in Australia indicates, subsurface temperatures across the tropical Pacific remain much colder than average over a large area. There is a growing region of subsurface warmth beginning to pool in the western Pacific but it lacks a real mechanism to drive it eastward- a so-called westerly wind burst. We typically don’t see those unless there is a significant pressure change across the Pacific and that shows up in the SOI or Southern Oscillation Index. When it is substantially negative, and persistently so, the trade winds often slow or even reverse, allowing the warm water gathering in the western Pacific to migrate eastward.

The latest update from the BOM also points out that long range climate models suggest a gradual warming of the tropical Pacific as the La Niña fades. This means it is likely that we’ll see a return to more average, or neutral ENSO conditions (ENSO stands for El Niño Southern Oscillation) by the time summer arrives in the Northern Hemisphere. There is also the possibility that the warming will continue and a weak El Niño could set in by next fall. I do not see any evidence yet to suggest that a strong El Niño is coming. However, this time of year, it is difficult to predict what will happen several months down the road but the large subsurface cold pool coupled with a fairly strong SOI signal over the past 30 to 90 days tells me that La Niña is going to be the rule for a few more months at least.

Why does any of this matter? Aside from the effects outside of the hurricane season, which are far too detailed to get in to in this post, we typically see a more active hurricane season when El Niño is not present. This is due to the stronger and more numerous instances of wind shear, the change of wind speed and/or direction with height, over the deep tropics. El Niño events promote this negative impact to tropical cyclones where as La Niña events usually do not.

For now, the La Niña pattern will continue but we’ll watch for signs that it is breaking down and then we’ll see how much warming takes place in the tropical Pacific. The end result could have an impact, one way or another, on the upcoming Atlantic hurricane season. I’ll post more about the ENSO state next month.

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