August 30th, 2011
11:23 AM ET

How Irene's forecast missed the mark and why it could happen again

They know they missed it. Forecasters at the National Hurricane Center in Miami say when it comes to the strength of Hurricane Irene as it approached North Carolina, they know they were off. Way off.

“At least in the guidance we were looking at there was no indication of anything that would cause the storm to weaken. So, we thought we would have a Category 3 at landfall,” said Bill Read, the director of the Hurricane Center. Irene came in at a Category 1, the weakest. Read said there’s good reason they were so far off.

The science of forecasting how strong or weak a storm will become is simply not very good. With Irene, forecasters say they weren’t even as good as their five-year average.

“Every storm comes up with a surprise,” Read said. “In this case it was one where it went downhill. Charlie a few years ago is one that went uphill. Neither case did we see that coming, and that’s my measure of the fact that we have a long way to go.”

Bill Read, of the National Hurricane Center, talks about the difficulty of predicting hurricanes.

Hurricane forecasters say they want to get it right all the time. But if you are going to be wrong, they say it's better to be wrong in weakening storms like Irene.

“I’d say a bigger worry than one weakening at landfall is the ’35 hurricane that came through the Keys," Read said. "Charlie if it’s a little bigger. Audrey in 1957. Get the picture?”

In all of these cases, the storms rapidly intensified as they neared the coastline. By then, it’s too late to order massive evacuations.

CNN's severe weather expert Chad Meyers said when Hurricane Irene smashed into the Outer Banks of North Carolina, the contact weakened the storm.

So, forecasters had the path right, but the impact of landfall changed what the amount of destruction would be in some areas. Wind shear helped knock down velocity, and unexpected dry air sucked some of the power out of the storm.

"It literally knocked the stuffing out of the eye," Myers said. "It never got its mojo back."

Meteorologists measured pressure levels inside the storm that could have allowed it to strengthen back into a Category 3 hurricane, Myers said, but Irene's romp over land in North Carolina prevented the eye wall from spinning into a more destructive storm by the time it arrived in New York.

"It never had that opportunity because North Carolina got in the way, dry air came across over Virginia and Maryland and got in the way, and although this was very low pressure, the reason why we could never let the guard down for New York City ... was because the pressure was low enough that at any time, if this storm decided to get its act together, it could have gone from a 60-70-80 miles per hour storm - it easily could have been a 110 (miles per hour) storm like it was in the Caribbean and like it was in the Bahamas."

Add to that the difficulties of having true accurate model data when it comes to hurricane forecasts.

“Real-time observations, like that collected by NOAA’s Hurricane Hunters, are put into these models to hopefully give a more accurate forecast. We are much more accurate on forecasting severe storms and their behavior for this very reason, the availability of observations," CNN meteorologist and weather producer Sarah Dillingham said. "These storms occur over land, allowing scientists to take measurements within those storms and use that data to run computer models. Think about a hurricane, over water, with no way to collect data except from above.

"Makes it difficult to see what is actually going on, right?"

Dillingham said dropsondes, instruments that are dropped from above and into these storms, are used to collect data inside hurricanes as they fall to the surface.

"This is helpful, but you are also trying to view the data it collected, track where it was in the storm, and at the same time determine what that means from a scientific perspective," she said. "Also, you may think, what about trying to send something up into the storm from below. In a hurricane? Good luck with that."

Dillingham said "the sparsity of real-time observations in tropical systems is what makes it so difficult to produce a more correct intensity forecast, and certainly makes it difficult to improve them."

"The track of these storms depends on atmospheric winds and surrounding storm systems, and we understand these factors much better, giving us a better handle on the 'steering' of these systems," she said. "This makes tracking more accurate overall. Things like RI, or rapid intensification, in tropical cyclones is just not fully understood yet, and until we can obtain that vital observational data within these storms - while they are over open, warm waters - we will struggle to model these kinds of processes.”

For that reason, Dillingham said Read's explanation of why they have trouble making these predictions is spot on.

And that's also why Read says the decisions to evacuate made by emergency managers and state and federal officials was the right one.

In every aspect of the storm except for wind speed, Read says, they got it right.

According to their initial analysis, the track forecast of the storm was 20% better than their five-year average. They do very well at predicting the path of a hurricane.

“We had storm surge flooding all the way up from the Carolinas into New England," Read said. We’ve had tremendous and tragic rainfall flooding. We’ve had loss of life from trees down well inland and the power outages.”

Hurricane forecasters admit their ability to foresee a storm’s strength is not much more today than it was 20 or 30 years ago.

According to the Hurricane Center’s initial analysis, “Irene exemplifies the state of the science.” They are pinning their future hopes on programs like the Hurricane Forecast Improvement Project. Scientists say they are seeing some promising results. This program uses high-resolution models and enhanced Doppler radars to measure the core of Hurricanes.

Forecasters say that three out of four times you will likely be asked to evacuate and you’ll coming back saying "Why did I leave?"

But that fourth time, if you don’t, Read says, you’ll wish you had.

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Filed under: Flooding • Hurricane Irene • Hurricanes • Weather
soundoff (639 Responses)
  1. aNN

    Wow, maybe the public could have done a better job. Next time let people put their fingers in the air to see which way the wind blows.

    August 30, 2011 at 4:59 pm | Report abuse |
  2. John Zurek

    The forecasters weren't off – The media was completely off. The heavily hyped power of the storm was a result of what is called "the media echo chamber" – A phenomenom where multiple 24-hour news stations try to outdo each other on a continuous basis. Station A picks up a news item – Station B reports the same but exaggerated – Station C throws even more oil on the fire. Before you know it, a trivial news item suddenly looks like the end of the world is upon us. It was the same with the reporting on Irene. A bit lame for the media now to blame the weather forecasters, after all the hype they put out the past week. This ticks me off. Why? Becuase scrupulous insurance companies use all this BS as an excuse to jack up our insurance premiums. Which they have been doing now for the past 5 years with not a single hurricane to strike the USA during that time. There should be laws on the book against hyping the news. Oh wait – That requires action from Congress. Right. Forget what I said.

    August 30, 2011 at 5:00 pm | Report abuse |
  3. NC

    I don't blame the forecasters. I'm glad Irene weakened and did not do more damage than it did. I DO BLAME the media for their attempts to turn every possible event into the apocalyptic movie of the week! Yes, it was forecast to be a bad storm. Yes, it turned out to be very bad in some areas. But now there are people whining about the let-down just because New Yorkers didn't flood up to their eyeballs. Get your priorities straight, people.

    August 30, 2011 at 5:02 pm | Report abuse |
    • Schmedley

      Couldn't have said it better myself...

      Before they were looking for a big storm for a big story. Now they are looking to create an issue about a non-issue.

      The forecasters were right to be conservative because you can't know if something will happen and the storm will suddenly pick up strength. Better to err on the safe side than to underplay the storm and get another Katrina.

      August 30, 2011 at 6:04 pm | Report abuse |
  4. Ydnar

    It was clear the system was going to loose it's juice but forecasters and the media kept hyping it up that New England needs to be ready and talking about anything except for the end of the world, when Irene was a Cat 1 at Landfall you still had forecasters running around their computers because it still had potential to get back up to a cat 3 near 80 degree water.
    I am not pro forecaster but when you have two strong high pressure systems which contain dry air masses, New England had been dry (takes longer for precip to work through) working a storm that you know is going to weaken, accelerate and loose power due to land, cooler waters and two large domes of air mass. yeah that hype is going to die quick. This is why when the weatherman and the media tells us to brace for the worst, nobody does. They stare at a computer form their own opinion as to what they think will happen, then it ultimately becomes up to us as to which hype or forecast we want to pay attention to.

    August 30, 2011 at 5:21 pm | Report abuse |
    • robot

      Please learn the difference between "LOOSE" and "LOSE"

      Drives me nuts. And ya did it twice.


      August 30, 2011 at 5:56 pm | Report abuse |
    • Hugo

      It's spelled "lose its power" please learn correct use of spelling and grammar. Your article is an aggravating read.

      August 30, 2011 at 6:09 pm | Report abuse |
    • 40acres

      Perhaps you should work for the weather service if you know so much about it and could have predicted the outcome more accurately and before they did. Or perhaps you are using a little 20-20 hindsight....which they can't do. Would you have told people to just relax and stay won't amount to much?

      August 30, 2011 at 6:11 pm | Report abuse |
  5. Smile

    It smells very bad!!!
    You know nothing, just wanna spent our more money, right.
    Now you're talking about the Climate Change...
    La, la, la, la

    August 30, 2011 at 5:26 pm | Report abuse |
  6. rjg

    The reason why the intensity forecast is hard to predict is because it depends on extremely local conditions... passing over a concentrated area of warmer than normal water will cause a quick intensification. However, the path's, which are easier to predict in general because they are affected by the large scale systems around the storm, aren't accurate enough to predict exactly where the storm will go. Hence, the intensity forecasts will be off for a long, long, time.

    August 30, 2011 at 5:27 pm | Report abuse |
  7. LouAZ

    Oh my . . . the CNN media at it's finest . . . asking the tough questions ! BS !
    Next thing CNN wants to know is what a Next Saturdays winning lotto numbers.
    How about why that cloud looks like my Aunt Grace ?
    You never ask "questions" like this weather story about Wall Street. Why Not CNN ?
    You never ask "questions" about economic policy from the House or Senate. You ask fluff questions then let them tell you what they want to tell you. You havn't asked Canter about NOAA funding . . . why not CNN ?
    This is LAZY "journalism" at its worst.
    No wonder Sharon Angle wouldn't answer your penetrating question about what time it was in Nevada.

    August 30, 2011 at 5:31 pm | Report abuse |
    • Lydia

      If you don't like CNN so much, just don't watch it and run to faux fox. It's probably more your speed anyway.

      August 30, 2011 at 6:15 pm | Report abuse |
  8. Nate

    The media hyped it up so people would go out and spend their money on things like generators and such. Boost the economy baby. Thanks again CNN and all the American media for your great reporting.

    August 30, 2011 at 5:42 pm | Report abuse |
    • Lydia

      You should talk to the people that were left with nothing. While it didn't hit NYC as expected, it dumped loads of water in other parts of NY, NJ, Vermont, Ct and decimated whole communities.

      How can one blame the weather forecasters? Nature did what it wanted. No less. No more.

      I, for one, was one of the lucky ones. And yes, I'm going out to buy a generator because there are many folks still without power.

      Hurricanes are always news events because of the destruction they can cause. Because NYC wasn't devastated, that's no reason to become so critical that you were so inconvenienced it didn't destroy your property. How inane!

      August 30, 2011 at 6:24 pm | Report abuse |
  9. Carol

    I think you all did the right thing. You never know what these storm will do, you have to prepare for the worst, and hope for the best.
    I was in Charlie's path when it made the turn east and had $45,000 worth of damage to my house. Did I blame the forcasters for not knowing it was going to turn and hit my area, NO. Was I prepared incase it did YES.

    August 30, 2011 at 5:45 pm | Report abuse |
  10. dmack89

    For those of us farther North (upper NY, Vermont) the forecast was spot on as we are still dealing with rising water damage, 10s of thousands still without power, thousands of homes damaged – if onto outright destroyed....etc. the wind speed may have died at the coast, but a storm is a lot more than just the coastal wind and storm surge. Irene was every bit as dangerous as predicted, if not more so, for many of us.

    August 30, 2011 at 5:47 pm | Report abuse |
  11. onthebeac

    Kudos to the weather guys that stay up late at night trying to make sense of all the data in order to make their predictions/forecasts. After living in Miami for 10 years, I'd rather be inconvenienced for several days evacuating across the state ( listening to "hype" ) than to watch my house get ripped apart as I float out to sea on an inner tube....because I didn't heed their warnings...

    August 30, 2011 at 5:48 pm | Report abuse |
    • Lydia

      You couldn't have said it any better!

      August 30, 2011 at 6:26 pm | Report abuse |
  12. Mike

    People want to come to America because it's full of fools who are easily parted from their money.

    August 30, 2011 at 5:54 pm | Report abuse |
    • Lydia

      Mike, next time keep your radio and tv off. Perhaps we'll be lucky if the next storm sweeps you off to sea. And those fools who purchased generators, batteries and bottles of water can watch as you float by.

      August 30, 2011 at 6:30 pm | Report abuse |
  13. Reality1

    The same clowns that can't accurately the weather tomorrow afternoon, are supposed to be trusted to forecast temperatures 100 years from now. Or at least that is what the deranged morons promoting global warming keep trying to peddle.

    August 30, 2011 at 5:55 pm | Report abuse |
    • Paul

      The stupidity here is entirely yours. Pick up a dictionary, and learn the difference between weather and climate. And try not to make such a total fool of yourself in a public forum again.

      August 30, 2011 at 6:05 pm | Report abuse |
  14. I95FL

    My prayers go out to those affected by Hurricane Irene. We here in Florida were pretty lucky that Irene didn't slam into us. Forecasting is not an exact science. Especially when you have a storm that forms over water. The only way to survey it is from the air, which, BTW, the government was cutting THAT budget (the Hurricane Hunters) by $10 billion. Remember the movie TWISTER. They used the tornado itself to pull up the instruments that took the measures. There a many, many stormchasers on land, which yields more and more data about what happens inside a tornado, ever here of a stormchaser in the Atlantic ocean? Let's hope Katia stays way off shore. Nobody needs another storm on top of IRENE.

    August 30, 2011 at 5:57 pm | Report abuse |
  15. drager

    Do these computer models take into account the position of the moon, curvature of the earth, characteristics of the geomagnetic field, undersea currents, solar reflectivity, atmospheric particulate densities, and global air mass patterns? If not, maybe they should look into them.

    August 30, 2011 at 5:58 pm | Report abuse |
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