Hurricane Irma is coming – I just don’t know where it’s going

A lot of people have asked about our app – it is called Hurricane Impact and is available on the iPhone App Store. Search Hurricane Impact

8 AM ET September 2, 2017

I am back home in North Carolina after a 10-day saga in Texas dealing with hurricane Harvey. That story is still very much ongoing, obviously, as the early stages of clean-up and recovery begin. The Harvey field mission was very successful with wind and pressure data being collected in Corpus Christi and several unmanned camera systems being deployed during both the hurricane impact and the flood impact.

Now it is time to focus on Irma.

Hurricane Irma five day forecast points plotted over upper ocean heat content map. The future track takes Irma over increasing sea surface temps as well as increasing upper ocean heat content - which will result in significant intensification.

Hurricane Irma five day forecast points plotted over upper ocean heat content map. The future track takes Irma over increasing sea surface temps as well as increasing upper ocean heat content – which will result in significant intensification. Click on image for full size.

Right now, the hurricane is fluctuating between category two and category three intensity as it moves over water temps that are just warm enough to sustain the heat engine. In a couple of days, the water temps will increase quite a bit, providing more fuel for a much stronger version of Irma than we see now. Fortunately, it will still be far away from any land areas.

The first region to consider for potential impacts, either direct or indirect, will be the Leeward Islands, especially the northern Leewards.

So far, the official forecast track from the NHC keeps the core of Irma to the north of all of the northern islands and presumably Puerto Rico. However, it is too soon to know if this will verify or not. The ECMWF model is fairly close to the islands while the GFS is notably farther to the north as Irma passes by. We are going to need another 48 hours or so to work out the details of this portion of the track for the hurricane and in my opinion, the west-southwest dip that is forecast will be the key here. The longer Irma remains at the latitude of the islands when the high pressure to its north eases up and allows the hurricane to gain more latitude, the greater the risk for a direct hit. Interests from Dominica to Puerto Rico should be paying very close attention to Irma over the next few days. In this case, timing will be everything – the later that turn back out of the WSW dive the more the risk increases.

After the next five days, the focus will shift to the Bahamas and the Southeast coast, including Florida. This part of the future track of Irma remains very uncertain. Both of the major global models, the GFS and the ECMWF, suggest a possible threat to the region in about a week to ten days. Here too, it will be all about timing and position.

As Irma moves westward, steered by a strong Bermuda High, a trough of lower pressure in the atmosphere will dig in to the nation’s mid-section, bringing a wonderful shot of fall weather to a good deal of the eastern U.S.

This trough will push on and erode the western portion of the Bermuda High. This will allow Irma to gain latitude once again – presumably. It all depends on how far north Irma is once the trough digs in. A more northerly and faster west track would place Irma closer to the weakness that the trough will create – allowing for a chance to turn north and then maybe northeast and out to sea.

On the other hand, if Irma if farther south and east, the trough digs in, then lifts out a few days later, allowing the Bermuda High to build back in – sending Irma on a NW track towards the Southeast. There are multiple variations of this scenario but the overall idea is, in my opinion, going to come down to how far west and north Irma is when the trough begins to lift out.

Since we are talking about at least seven days from now, it is impossible to know what will happen. For this reason, everyone from the Bahamas to Florida to the Canadian Maritimes should be keeping tabs on Irma every day. There’s no reason to worry just yet in any particular location. Right now, as I am doing with my family, just add a little more to your supplies each time you visit the store. An extra gallon or two of water, maybe have your generator checked if you’ve used it anytime in the past. Do these small things now before the stress and anxiety ramps up next week – which it very well might for some people.

We have time right now to watch and react at a steady pace. Maybe it will be ok and Irma will turn out to sea. If not, luck favors the prepared and my advice is: start preparing a little more each day from here going forward. You just might need it.

I will have a video discussion posted later this afternoon which will go over the latest from both the GFS and the ECMWF.

M. Sudduth

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Models hinting at possible first hurricane of 2017 season

Graphic from Colorado State University's July hurricane season forecast outlook showing the below avg wind shear (blue color) across the MDR for the month of June.

Graphic from Colorado State University’s July hurricane season forecast outlook showing the below avg wind shear (blue color) across the MDR for the month of June. Click for full size.

The update from Colorado State University to the 2017 Atlantic hurricane season forecast made mention of the fact that, during the month of June, sea-level pressures were well below average across the deep tropics – also known as the MDR or Main Development Region. This is the area between Africa and the Lesser Antilles and has seen its share of powerful hurricanes over the decades.

In recent years, however, the MDR has been notably quiet. Dry air, strong upper level winds and generally higher than normal pressures have kept the region much more benign – resulting in far less hurricanes such as what we saw in 2004 with Frances and Ivan, as examples.

This year, it is becoming more and more obvious that the sleeping giant is awakening, so to speak. Water temps across the MDR are above normal, wind shear is below normal and surface pressures are below normal. The result thus far has been the formation of tropical storm Bret last month (extremely rare to have MDR tropical storms in June) and now, most recently, tropical depression four – technically a tropical cyclone though below tropical storm intensity. The only significant mitigating factor keeping TD4 in check has been a large Saharan Air Layer or SAL event that has pushed ample dry air in to the deep tropics, smothering the depression and keeping it from strengthening further. This SAL outbreak is typical for July, having a tropical depression in the MDR is not.

ECMWF model at day 5 from last night's run showing energy or vorticity at the 850mb level of the atmopshere (circled in green). Image courtesy of Levi Cowan - tropicaltidbits.com

ECMWF model at day 5 from last night’s run showing energy or vorticity at the 850mb level of the atmosphere (circled in green). Image courtesy of Levi Cowan – tropicaltidbits.com. Click for full size image.

Now comes the next chapter in this story. Both the GFS and the ECMWF are now indicating the development of a tropical storm originating from a tropical wave that is about to emerge from the African coastline. I want to be clear, the development happens beyond the 5-day time frame but well within the next 10 days. Since both of these global models now indicate this happening, it has my attention. In fact, both models go on to develop the system in to what would likely be a hurricane later on in their forecast periods but again, not at some ridiculous time frame such as 10 to 14 days out – what many consider to be “model fantasyland”.

What concerns me about this is the mere fact that it is still early July, several weeks ahead of the traditional beginning to the normal run-up to the peak of the season and we’re talking about yet another MDR system trying to develop. In other words, if it’s this busy now, when climatology says it should not be, how busy will it be when the natural background state is inherently favorable? That usually sets in around August 15-20 and lasts until the end of October.

I make it a point to refrain from being an alarmist – those who have followed my blogs and video discussions know this and I stand firm behind that belief. At this point, I am beginning to worry that this season could end up exceeding all of our expectations in a bad way. The time-tested saying of “it only takes one” remains intact but this is the kind of season where we could be looking at multiple “it only takes one” events. Please keep in mind too that I am not talking about just the United States in terms of impact. The Lesser Antilles are front and center for any action that rolls out of the MDR and west of there we have Puerto Rico, Hispaniola and Cuba. This is the kind of season that could affect a lot of people across the Atlantic Basin and in areas that can least afford such bad luck.

I am going to say it, the signs are ominous right now. We’ve gone a long time without experiencing a category three or higher hurricane in the United States. They’ve also been somewhat rare elsewhere with the exception of Matthew and its devastating impacts on Haiti, eastern Cuba and the Bahamas last year (Joaquin in 2015 also impacted portions of the Bahamas). It is time to take notice and be ready to act.

Needless to say I am going to be watching the evolution of this next potential system very closely over the coming days. Perhaps it is just a blip in the models and subsequent runs will drop the storm/hurricane completely and we can all breathe a sigh of relief. I will post a detailed video discussion concerning this potential development later this afternoon once the morning model runs complete and are available.

M. Sudduth 7:45 AM ET July 7

 

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Hurricane watch for portions of Haiti, all of Jamaica

Recent visible satellite image of Matthew. Notice the clearer eye now, it had been clouded over earlier in the morning.

Recent visible satellite image of Matthew. Notice the clearer eye now, it had been clouded over earlier in the morning.

The latest update from the NHC now indicates a hurricane watch for two areas in the Caribbean Sea: all of Jamaica and the western portion of Haiti. This means that hurricane conditions are possible in the watch area within the next 48 hours or so.

Matthew continues to move slowly west with winds of 145 mph. Some westerly shear has impacted the circulation and caused the hurricane to weaken overnight from its incredible peak of 160 mph. As of this writing, the eye seems to be clearing out again meaning that perhaps some slight re-organization is taking place but these ups and downs are to be expected, especially with exceptionally strong hurricanes. It is likely that Matthew will be a strong hurricane as it approaches Jamaica and western Haiti on Monday.

Interests in the two island regions need to be preparing for a hurricane at this time. Heavy rain, which will surely lead to flash flooding and mudslides in the mountains of the two countries, along with dangerous seas and high winds will be the expected impacts. To what extent each of these hazards will affect the area remains to be seen. We will know more tomorrow as Matthew gets closer and we can see how strong and well organized it is. Obviously the closer the core tracks to either location, the more pronounced the effects will be.

Next up will be a landfall in southeast Cuba along the Caribbean coast. The mountain range that runs east-west across Cuba at that latitude will disrupt the circulation of Matthew some but it is forecast to reach category three intensity once again over the very warm waters of the southwest Atlantic.

The next few days are fairly certain in terms of the forecast track for Matthew. It’s what happens after Cuba that has tremendous uncertainty. Essentially it’s another duel between the GFS global model and the ECMWF global model with other models picking sides either way. Instead of trying to figure it all out with lengthy explanations of why one model shows this and why one shows that I want to set a benchmark – point in space and time to watch for.

If Matthew goes over Jamaica, the center of the hurricane that is, then the GFS seems to have the right forecast so far. If it goes over Haiti, then the latest runs of the ECMWF are doing better. We will absolutely know the “winner” by Monday. It’s that simple in terms of the short-term (3-day) window of which model is performing best on track. From there, we will have ample time to prepare in the Bahamas and the United States as needed.

I will post one or two video discussions on Matthew later today here, our YouTube channel and to our app, Hurricane Impact.

M. Sudduth 11:05 AM ET Oct 1

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ECMWF indicates strengthening Hermine making landfall in FL panhandle

12z ECMWF

12z ECMWF (courtesy of tropicaltidbits.com)

The morning run of the ECMWF model indicates that tropical storm Hermine  Will gradually strengthen up until landfall near the Central panhandle of Florida. Take a look at this image valid Friday morning showing strong energy or vorticity in the lower levels of the atmosphere.  This indicates a fairly well developed tropical cyclone and it is possible that Hermine will be a hurricane at landfall.

Right now, the biggest impact still appears to be storm surge flooding and this will encompass a fairly large area of the Florida Panhandle from Apalachicola beyond the Big Bend area.  Obviously the stronger the storm becomes the higher the storm surge is likely to be. Residents in the area of the hurricane watch need to be preparing for hurricane conditions there’s no doubt about it;  plan for a hurricane and don’t wait to see what happens.

I am currently in Savannah on my way to Lake City, Florida. I will post a full video discussion this evening.

M. Sudduth 3:50pm ET Aug 31

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When 80% is not enough

Wednesday, August 17 at 2pm ET the National Hurricane Center issued the first outlook on what would become probably the most talked about area of interest (invest) in the history of mankind. That outlook began a process that kept scores of weather geeks, emergency managers, TV meteorologists, weather forecasting firms and the general public glued to their Internet-connected devices. From the get go it looked like this could be “the one”. It had potential to make it all the way across the Atlantic and possibly affect the United States after roaring through the Caribbean. And so here we are at the other side of that long journey and what became known as “99L” to millions of people will long be remembered for what it didn’t do: failed to develop.

As the process of tracking the tropical wave got underway, computer models were generally in agreement that the system would move westward at a fairly low latitude. However, it was clear early on that mid-level dry air, somewhat associated with the Saharan Air Layer (SAL), would be an inhibiting factor for development. Never the less, by early Saturday morning the 20th, it looked as though a tropical depression would form. Chances went from virtually nothing to 50% in just three days.

By Monday evening the 22nd, the probability increased to 60% and it looked as though a hurricane was possible for the southwest Atlantic Basin, maybe even close enough to Florida or the Carolinas to warrant concern. The social media hurricane machine was in full throttle mode with every expert (and non-expert) opinion you could imagine being thrown in to the mix. It was “invest 99L” overload and it would only get worse.

Leading the charge for development at first was the dynamic duo of the GFS and the ECMWF. Both seemed to latch on to 99L and make something of it. At first, it looked like a track towards Florida and then a turn north was likely. At times, the GFS had an enormous hurricane sitting not too far off the North Carolina coast, moving harmlessly out to sea in the longer term. It looked like this would be a close call but no guarantees yet for a landfall.

As the days went by, seemingly very slow considering we can watch the computer models come and go virtually 24 hours a day, things began to change. The GFS dropped the development almost completely while the ECMWF put memories of Katrina, Andrew and Betsy in our collective minds. It wasn’t just the Euro, the new and improved HWRF model, which is specifically designed to forecast tropical cyclones, showed similar forecasts of a hurricane headed towards south Florida and then turning west as it tracked south of a strong high pressure area over the mid-Atlantic. The hurricane world went in to full meltdown mode. It had been since before Twitter, Facebook as we know it, the iPhone and even the birth of One Direction that Florida had been hit by a hurricane. It was Tuesday, August 23 and 99L had a 70% chance of developing in to at least a tropical depression. The “H” word was bound for Florida.

To make matters worse, the ECMWF ramped up 99L to beast mode and sent it towards Louisiana, the LAST PLACE that needs a hurricane this season. Meanwhile, the GFS showed almost nothing at all. Just weak energy coming across and never really doing much. People were scoffing that if the Euro was right, congressional hearings needed to take place immediately to “fix the GFS!”. It was pure madness because, you know, the ECMWF nailed Sandy’s forecast from 8 days out. People were hung up on a hurricane from four years ago, forgetting the failures of even recent events like Erika last season and Fiona in 2010. Oh yeah, let me tell you about that one.

In 2010, we had Earl, headed for a possible landfall up the East Coast. Meanwhile, the ECMWF was advertising Fiona to be “the next Katrina”. A few in the weather business bit off on this and ran with it like the end times were coming. Earl was going to be a dud while Fiona would be a disaster of epic proportions. All the while, the GFS showed Earl doing exactly what it ended up doing: coming close to the NC Outer Banks then turning out to sea as a strong hurricane. As for Fiona, the GFS showed it as nothing more than a nuisance and that’s how it all turned out. GFS right, Euro wrong. Funny how few people remember that. I remember, trust me, I was on the Outer Banks where Earl brought 85 mph wind gusts to our anemometer that was set up next to Oregon Inlet.

By Wednesday morning, just 48 hours ago, the chance for 99L to develop made it to 80%. It looked like a sure thing now. I mean 80% is pretty good, right? In basketball an 80% free throw shooter is considered to be almost lethal from the line. You foul that player and you might as well put two points on the board. Eight times out of ten the shots go down.

But what happens when that player is in the title game and his team is down 1 with .90 seconds on the clock and he is fouled driving to the hoop? Everyone holds their breath as he lofts the first shot to tie the game. He misses. It’s stunning. The announcers balk about his percentage and how they can’t believe he missed. Must be the immense pressure. Time for try number two. He misses. No one gets the rebound and the clock expires. His team loses the National Championship for one simple reason: 80% is not enough. It’s not 100%. There was a 20% chance he missed either of those two shots. Now this is purely hypothetical but it makes my point. Sometimes high probability is mistaken for certainty.

In the case of 99L, it looks dead and gone now. The GFS, in its past few days of runs, turned out to be correct, for the most part. No hurricane coming for south Florida this weekend like the Euro showed. To be fair, the HWRF did as well and it busted big time. Instead, the Euro now has weak energy bringing possible heavy rain to portions of Florida. No hurricane in to Louisiana or elsewhere, just a strung out mess.

Odds of development over the next five days are down to 60%. Strong wind has all but beat the system in to oblivion. There is virtually no convection or thunderstorm activity with it and the USAF Hurricane Hunter crew has been grounded since there’s nothing there to investigate.

Sixty percent. Hmmmm. That’s not too high nor is it very low either. What is the reason behind this number? It’s because there is still a chance, apparently a 60% chance as of this writing, that 99L will develop some in the Gulf of Mexico. How could this be? The Euro “dropped it”. Well, the ever-excited HWRF sure didn’t and the GFS now shows limited development in a few days with some rather wacky tracks thrown in for good measure. To be honest, it’s giving me a headache to watch this day in and day out and all we have is an area of interest, even if fading to an area of blue skies.

I caution that while the gist of my post is aimed at pointing out the obvious, that anything short of 100% probability has a chance of falling short, it is also true that unless it’s zero, there’s still a chance. Even the 60% free throw shooter is sometimes the hero.

There is still some energy down in the region near the southeast Bahamas that might be able to survive long enough to warrant keeping an eye on. None of the computer models that show any development potential do so until later in the weekend – so let’s see what happens. Perhaps 80% was too high early on but 60% will be just enough for now.

We want to be able to trust the computer guidance to give us time to prepare if in fact something is going to develop. However, the public should understand probability and know the limitations of forecasts even in the relative short term. Most people don’t have time or interest to fully invest their energy in to making sense out of it all. I do my best and could not for the life of me understand why the GFS gave up on this system while the Euro did not. Sometimes you need to look out the window, so to speak, and view the actual weather and not just the predictions. The satellite presentation of 99L never really looked promising for development. It came close a couple of days ago but the reality was it didn’t have that “look”. So logic should have dictated that if it looks poor and one of the major global models insists on non-development, then maybe that’s why: because it won’t. It’s a simple concept and for now, it turned out to be right. Shear and lack of convection and overall organization has kept 99L from developing but it’s not necessarily over.

I think the next 48 hours will be all we need to know how this ends. If nothing happens by then and the wave of energy basically spreads out or dissipates completely, then we’re golden. Until that happens, it’s obviously prudent to keep an eye on things – just in case 60% is just enough to do what 80% could not.

I’ll have more in my daily video discussion posted here, to our app and on YouTube later this afternoon.

M. Sudduth 9AM ET Aug 26

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