The Difference Between Tropical And Subtropical Storms

Subtropical Storm Beryl is just off the East Coast tonight. Not very impressive to see.

Subtropical? When did that happen? How does it differ from a tropical storm?

Bad news first. If you’re in the path, subtropical or tropical will feel the same. Both have moderately strong winds and lots of rain.

Subtropical Storm Beryl is just off the East Coast tonight. Not very impressive to see.

Subtropical? When did that happen? How does it differ from a tropical storm?

Bad news first. If you’re in the path, subtropical or tropical will feel the same. Both have moderately strong winds and lots of rain.

Last night one satellite estimate showed a small area (of ocean) getting two inches of rain per hour!

The difference is much more important for those of us who forecast. It centers on the storm’s core.

The thunderstorms within tropical storms are part of an amazing chain. Warm humid air is drawn in from the surface creating towering ice clouds to 50,000 feet or more! There are strong horizontal winds, but there are strong vertical winds too!

In a subtropical system the thunderstorms and convection are taking place, but at lower heights. That limits intensification and strength.

Tropical and Subtropical Storms are easy to distinguish on satellite imagery. The subtropical has a much larger cloud free center.

My friend Bob Hart, a professor of meteorology at Florida State University, has a website which shows the transition through these different phases of a storm’s existence. It’s an interesting and useful forecast tool to have. It’s easy to see the level at which Bob researches and understands tropical weather.

Subtropical system do become hurricanes, though they must become a tropical storm first.

We are still very early in the season. It’s tough for any storm to get very strong. Normally the second named storm comes August 1.

My Sixth Sense And Earl

I can’t tell you why, but I have that same life threatening fear from Earl. Sixth sense? Maybe.

There are two tropical systems currently in the Atlantic. They are not alike. Weather is not like children. I am entitled to favor one over the other!

It seemed obvious from the beginning Danielle would be an ‘outside runner’ staying far enough out in the Atlantic to be no more than a curiosity. On the other hand Earl concerns me and has since its seed pushed past the West African Coast..

Over the years I’ve developed a sixth sense for this sort of thing. It usually works. Not always.

I wrote this five years two days ago:

The Hurricane Center has just christened a tropical depression. Though it hasn’t yet graduated to tropical storm or hurricane status, but “we’ve already picked out a name” – Katrina.

I am concerned by Katrina because it is likely to head toward South Florida, a densely populated area and where my parents live!

It doesn’t look like Katrina will be a major hurricane… but a minimal hurricane is enough for me.

You’ll be reading a lot more about this storm on this site over the next few days.

OK — I missed the major hurricane part which was still well in the future. Still, something compelled me to follow Katrina closely. I was blogging about it a lot long before anyone suspected the kind of trouble it would cause. Even without my post-New Orleans posts it is my most blogged hurricane.

I can’t tell you why, but I have that same life threatening fear about Earl. Sixth sense? Maybe.

It doesn’t make a difference. Tropical systems all receive close scrutiny. The risk is just too great.

Prepping The Public For Hanna

Nasty is a word I used and reused today. I thought it was appropriate–probably more meaningful than numbers alone.

hanna.gifMy job is interesting and often misunderstood–even by some of my co-workers. My goal isn’t to get the viewers to remember a specific temperature, wind speed, or other forecast parameter. I need to leave them feeling the next day’s weather. I want people to walk outside the next day and go, “Yeah, that’s what I was expecting.” Few people can get to that point with numbers alone.

The job becomes more difficult with a tropical storm passing nearby. Within the next 24 hours Hanna will slide by just to the south of us. It’s a named storm. Even those with no tropical experience will pay attention.

The forecast seems reasonably easy. Hanna will be moving rapidly, picked up by the jet stream winds. Slower moving tropical systems are much more difficult to pin down. You never get 100% of the forecast right, but I’m pretty confident right now.

I tried as hard as I could to explain what Hanna would and would not be. We aren’t being hit by a hurricane or even directly by a tropical storm. Some of the day might be dry. The wind will ramp up late. The worst of the day (actually night) will be nasty.

Nasty is a word I used and reused today. I thought it was appropriate–probably more meaningful than numbers alone.

There will be problems. They’ll more likely be scattered than widespread. If a problem hits you, scattered and widespread become hollow words, It’s tough to predict where a tree will sever a power line or a clogged storm drain will flood a street.

I’m working Saturday. I need to keep things in perspective while on-the-air. Overdoing the warning has long term implications just as bad as underdoing the warning.

There’s a lot to ponder. Twenty five years of weather forecasting and it’s all still very complex and very much a challenge.

My Beef With The Hurricane Center

Since Friday, I have traded emails with Ed Rappaport, director of the National Hurricane Center down in South Florida. He responded after I sent an email to two of his forecasters.

I was upset… No, I was livid the National Hurricane Center had decided to stop tracking and issuing bulletins and forecasts on Hurricane Noel Friday at 5:00 PM.

I’ve attached their final forecast discussion below. Two things to note. First, when they stopped their forecasting, Noel had already begun to take on non-tropical characteristics.


Second, and much more importantly. Noel was going to get stronger!


From a purely meteorological standpoint, NHC was correct. Noel was no longer a tropical system. They cover tropical systems – period.

That misses the point. The Hurricane Center’s job is to protect lives, not be meteorological purists.

When they stopped issuing forecasts, advisories, bulletins and maps, the job moved to the local forecast offices, like Taunton, MA and Upton, NY. Those offices have very capable forecasters (some of whom I’ve known for two decades).

Again, that’s missing the point.

By changing Hurricane Noel to an unnamed extratropical low, NHC signaled a diminished threat to the untrained public. That just wasn’t so.

There is already enough concern for public perception that the term “minimal hurricane” is no longer used in public bulletins.

Public safety officers, emergency managers and even broadcast meteorologists know exactly when and where to get data on tropical systems. It is specific and very different data than any other forecast product we get. The data from the local offices is totally different.

In the case of broadcasters, we all have equipment which automatically produces maps as the Hurricane Center’s data comes in! When that stopped, the ability to produce the most compelling and illuminating maps stopped. These maps made the case Noel meant business.

Based on the response I received from the director, I wonder if a “Hurricane of ’38” scenario would also see the Hurricane Center back off!

Something’s got to be done. That’s the bad news. The good news is, these are very bright people. I hope they find a way to change their policies before someone gets hurt.

Continue reading “My Beef With The Hurricane Center”

Must Be The Season

I spend a lot of time watching the tropics. It comes with my job. These tropical systems are fascinating and devious.

Right now I’m watching two with great interest. The first is Ernesto, off the Carolinas and officially just below hurricane strength.

When Ernesto’s path out of the Caribbean was first predicted by the Hurricane Center, it was centered in the Gulf. Actually, it was well into the middle of the Gulf. Ernesto actually moved up the center of Florida and emerged in the Atlantic.

Not even close.

This is not to say the Hurricane Center doesn’t do a great job. They get the word out, which is probably their most important job.

Even though Ernesto is a wimp, people will die and property will be destroyed. We can predict, not prevent. I feel frustration over that. Isn’t that silly?

Stef’s move back to college is scheduled for Saturday. That’s Ernesto’s big day in the Northeast. Darn!

The second storm is more interesting on an intellectual level, though it won’t affect me personally. That’s Hurricane John, in the Pacific, off Mexico’s West Coast.

John is on track to strike Cabo San Lucas. We were there in January.

Cabo is a beautiful seaport town. It’s at the southern tip of Baja California. Stretching south of the city, into the Pacific is a string of rocky islands, called Land’s End.

If John passes just west of Cabo, its winds will be out of the south. They’ll be guided by Land’s End, piling water into the harbor and flooding all the low lying areas. Meanwhile, damage to the homes and businesses built on the surrounding hills will be immense.

Again, as with Ernesto, I can see it happening in my mind’s eye. It’s like watching a car crash in slow motion. There’s just nothing I can do about it.

With proper warning, most people will be saved. You can’t move a building. You can’t stop the terror for those who have nowhere else to go, or the uncertainty for those who get evacuated.

You Never Forget Your First… Storm

So, here we are on June 10, and the first tropical system has formed in the Caribbean. Winds are ‘light’ at the moment. The storm remains an unnamed (only numbered) tropical depression.

Last year’s first storm formed on June 8 and in a similar place. It became Arlene and was an early non-entity.

People in Jamaica and the Cayman Islands have been dealing with torrential rains from this system for the past few days. We’re talking feet of rain, not inches!

I’m curious to see how this hurricane season plays out. For me, there’s awareness of every system – after all, it’s my job. Most people only perk up for the big ones… or at least that was the case until last year.

Will people hang on every word about storms destined to stay with the fishes? Probably – at least for a while. In years past, we often disregarded them on TV. This year, disregard at your own peril.

When this year’s season is over, and the hurricane count is down from 2005 (as it almost certainly will be), will those who make the connection between tropical systems and global warming make excuses? Probably.

If the count is up, I’ll certainly reevaluate my beliefs.

This first system… this little Alberto wannabe… looks like it will cross Florida and then parallel the East Coast. This time of year it’s tough for a storm to maintain any strength in the relatively chilly Atlantic. It’s also tough for a storm to have any westward motion – critical for it ‘hitting’ land from the Atlantic.

As far as I can tell, there’s never been a landfalling hurricane on the East Coast that moved through the Gulf.

Lots of eyes will be on this system. Lots of eyes will be on the Hurricane Center and anyone who forecasts the weather.

The “A” storm is usually pretty docile. Sort of like training wheels for weathermen. Except when they aren’t – Andrew, for instance.

Those were the ‘good old days.’ Back in 1992, Andrew didn’t form until mid-August. By August 16, 2005, we’d already seen Irene.

Blogger’s note: On the right side of the page, you’ll see links to the Hurricane Center’s official forecasts. Those are dynamic links which update through the season dozens of times a day.

Hurricane Info – Where To Go

This time of year, a lot of what I do is follow hurricanes. Many of the tools that are useful the rest of the year fail miserably with tropical systems.

There are a number of problems. Hurricanes… even big ones like Dennis, are often relatively small enough to fall between the cracks of the numerical weather prediction programs. So the computer models I’d normally follow aren’t particularly helpful.

Hurricanes can be very interesting when they’re far from land – away from radar and surface observations. Our government’s NEXRAD network is worthless until the storm is poised to hit land.

Here are some of the secondary sites I follow to try and get more info than would normally be available.

The spinning radar on the left side&#185 is from one of Cuba’s network of weather radars. On any given day, half of them might be out of service. In Cuba, that’s not unusual.

On the other hand, there are seven. That’s a lot for an island of Cuba’s size.

Even though the south coast of Cuba is within range of the Key West radar, there are mountains in the way. I think the Cuban radar does a better job at this position. It’s always surprised me that the Cuban images are on the net. I’ve used their sites for at least three years.

The College of DuPage, a two year college where you wouldn’t expect big time meteorology, has one of the best sites for ‘domestic’ imagery like satellites and radar images. DuPage has the full NIDS suite, meaning you can see the Doppler portion of Doppler radar – winds!

For prediction, I have been paying close attention to the MM5 model being run at Florida State by Bob Hart (originally of North Branford, CT). The MM5 was initially formulated at Penn State and runs on off the shelf hardware (though still beefier than what you’ve got at home).

What makes FSU’s iteration of the MM5 so special is its superior ability to properly see topography, ‘bogused’ data from the actual hurricane (to better set the initial parameters, and sophisticated physics.

Bob is among the smartest people I’ve ever known. It’s no surprise this forecast tool is run under his supervision.

Hurricanes are so difficult to accurately predict, especially using conventional methods. Any improvement in the state of the art becomes a possible life saver! What could be sweeter than doing your job and saving lives?

Finally, I look at the Hurricane Center‘s output. For me, seeing just the Hurricane Center’s work product removes the fun of doing it myself.

I do religiously read their technical forecast discussions. The link, unfortunately, changes each time they issue a new one. Links to NHC products are also on the right side of this webpage and on the Hurricane Center homepage.

&#185 – Because this webpage will live on long after Dennis is gone, this is a captured radar image. The link goes to the real thing.

Two Interesting Controversies… Well, To Me They Are

I thought I’d write about some interesting things I’ve read over the past few days.

The first seems to be a simmering controversy. It has not yet reached critical mass, but it should as soon as someone in the mainstream press catches on.

Is someone else fudging when it comes to global warming? Last week there were questions about a pro-industry push. This is just the opposite.

It starts with some comments on global warming from a respected scientist representing a respected organization

Kevin Trenberth from the National Center for Atmospheric Research (NCAR) claims that warmer oceans and increased moisture could intensify showers and thunderstorms that fuel hurricanes.

“Trends in human-influenced environmental changes are now evident in hurricane regions,” Trenberth said. “These changes are expected to affect hurricane intensity and rainfall, but the effect on hurricane numbers remains unclear. The key scientific question is how hurricanes are changing.”

All well and good, except this is a conclusion and a report steeped in controversy.

Dr. Chris Landsea is from the National Hurricane Center. He’s the guy who wrote the Hurricane Center’s FAQ. He is not a happy camper.

Shortly after Dr. Trenberth requested that I draft the Atlantic hurricane section for the AR4’s Observations chapter, Dr. Trenberth participated in a press conference organized by scientists at Harvard on the topic “Experts to warn global warming likely to continue spurring more outbreaks of intense hurricane activity” along with other media interviews on the topic. The result of this media interaction was widespread coverage that directly connected the very busy 2004 Atlantic hurricane season as being caused by anthropogenic greenhouse gas warming occurring today. Listening to and reading transcripts of this press conference and media interviews, it is apparent that Dr. Trenberth was being accurately quoted and summarized in such statements and was not being misrepresented in the media. These media sessions have potential to result in a widespread perception that global warming has made recent hurricane activity much more severe.

Landsea goes on to say global warming will have minimal impact (if any) on tropical systems down the road. In fact, Landsea has resigned from this board in protest of the books being cooked.

Earlier today Matt Drudge was linking to an article which quoted Dr. Trenberth with no opposing viewpoints or perspective I was upset, so I wrote the author of the story.


I appreciate you pointing this out. Unfortunately, the article was

published before I was finished with it. It was pulled off our site (but

not before it was picked up in other places), and I have now added some


I apologize for this mixup.

Michael Schirber


How much damage has been done? Who can tell. Even bad or retracted research sometimes takes on a life of its own. I’ll wait and see what’s quoted later.

On to the second bit of reading which concerns the space program. It’s not often I see something in the National Review I agree with (in fact it’s not often I see the National Review). Today was the day.

This time it’s an article by John Derbyshire about the space program and its dubious current value. This is something I’ve written about before here in the blog. It’s not a popular thing to say the space program is a total waste… but it is.

I wrote John (whom I’d never heard of before this evening) and he wrote back.

Thank you, Geoff. Excellent comments. I just did a radio spot with Jerry

Doyle — he’s a big shuttle fan & has swallowed all the NASA guff about

microgravity manufacturing & the rest.

I think of the Shuttle program as a sort of Brasilia of the skies — pure

1950s thinking. Who else, today, is riding a vehicle designed by slide



John Derbyshire

A Brasilia analogy – wow!

Stormy Weather

I was busy yesterday afternoon with some stormy weather that moved into Connecticut. I got an email from someone on the other side of the state who was unhappy I had broken into a soap opera.

That sort of thing comes with the territory. I have heard other weather people describing the same type of call or email. There is no question in my mind that I did the right thing. The writer will probably never agree.

At least the bad weather brought one thing – this unreal picture taken in Northfield, CT by Lou Belloisy. Lou’s an old friend and former chopper pilot for the station. I’ve seen his photography before, so this shot is no surprise.

I am jealous.

This is the kind of photo I’d like to take. Hopefully, I will. I understand the mechanics and technique, but there’s more involved. There will be more pictures like this one over time because more people with digital cameras will be willing to experiment, taking hundreds of photos and getting instant feedback.

Along with our thunderstorms, I’ve been watching two tropical systems closely because it looks like they might affect us – not as tropical storms or hurricanes, but as gusty rainstorms.

My forecast for Bonnie, the first, looks on target. Tomorrow should be very, very rainy. I’m not so sure about Charley, storm two.

Here’s the problem for me as a weather forecaster – I am very dependent upon the computer guidance. Every once in a while I’ll hear a forecaster poo poo the models, but that’s baloney. The reason we can have 5-6-7, even 8-day forecasts is because of computer modeling. No human could discern the weather patterns that far in advance without mathematical help.

Unfortunately, the medium range models, and to a lesser extent the short term ones, don’t see these tropical systems! They are compact, and usually occur in areas where data is sparse. As of this morning I can’t find Charley on the models we depend on for the first few days of the forecast, much less the extended forecast.

I know Charley will be there, so everything in the models he could interact with is probably wrong!

I try to look at special tropical models and integrate the data myself – but that’s not a great solution. There’s just too much physics taking place. I’m sure I’m missing things left and right. So, the extended forecast, when there’s tropical weather around, tends to be less accurate – which is a shame.

There’s no ‘level of difficulty’ excuse. If this forecast busts, people will be (correctly) upset. That’s what I get for claiming to be able to predict the future.

Looking to the Future

Much of my work time is spent looking into the future. I’m pretty good at it. Of course the farther into the future I predict, the less accuracy I have. On top of that, the more events that have to happen in a distinct order, at a distinct time, the less accuracy I have.

It is easy to look at the computer generated maps I get, with weather features neatly placed in exact spots, and assume that’s exactly where they’ll be. It doesn’t always work that way – though sometimes it does.

I’m giving you all these “CYA” statements before I tell you about some projections I saw earlier today. If what I saw comes true, this will be a terrible week here in Connecticut… actually, that’s an understatement. What I saw if it comes out exactly as I saw it would be the precursor for some pretty significant flooding.

The setup of two tropical systems in rapid succession is just what happened prior to the Connecticut floods of 1955. Since then flood control dams have been built in Litchfield County. It is doubtful the same thing would happen in the same place today. Still, there is just so much rain that can be dealt with before some significant flooding takes place.

Right now it’s Tuesday with the first tropical system scheduled to be here Friday. I’m not sure it will get us. I’m less certain of Sunday’s run in with the second storm. But the maps certainly have my attention right now and I will be on the edge of my seat as each new run of the models come in.

I seldom want to be wrong. I’ll make an exception here.