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. Jane

    i cant believe this!! me and my sister just got two i-pads for $42.77 each and a $50 amazon card for $9. the stores want to keep this a secret and they dont tell you. go here CoolCent. com

    August 30, 2011 at 3:55 pm | Report abuse |
  2. Hal

    Environmental wackoes are to blame

    August 30, 2011 at 3:55 pm | Report abuse |
  3. A scientist

    It's fascinating that given the choice between focusing on the positive (that forecasters nailed the path almost perfectly) or the negative (that they were off about the strength), CNN decides to focus on the negative. Weather prediction is an inexact science, and all things considered, this prediction was pretty close.

    August 30, 2011 at 3:57 pm | Report abuse |
    • Luigi

      I don't know where you get focus on the negative from. There appear to be a lot of people (if judging by the posts in forums attached to earlier articles is enough of a sample) blamed CNN for lying about the storm just to increase readership/viewership.

      In comparison, any negative that CNN may have done in the article pales in comparison to some of the comments made elsewhere by readers. Further, the readers aren't going to learn if they don't get new information about the area where they were wrong. Granted, I realize learning doesn't work simply by telling people "you were wrong." But somewhere it needs to be in the process.

      I suggest giving CNN a pass considering these other factors.

      August 30, 2011 at 4:09 pm | Report abuse |
    • jman57

      it really seems like New Yorkers are the ones crying "that's it??". And I'm a New Yorker.

      From what I can tell, Irene did plenty of damage to VA/NJ/VT and NC. But since NYers have a vast imagination and for some reason expecting flood waters to up midtown anything less caused them to question the whole of meteorology. Heck even upstate and Long Island took a substantial beating.

      Oh well, you damned if you do and damned if you don't.

      August 30, 2011 at 4:18 pm | Report abuse |
  4. beau

    If we can not predict a storm 4 days in advance, how can anyone believe scientists about global warming? Theory based science is not proof. Policies should not be made on scientific theories.

    August 30, 2011 at 3:57 pm | Report abuse |
    • basketcase

      Yeah all those scientific theories suck. Screw gravity I can fly if I think hard enough...

      August 30, 2011 at 3:59 pm | Report abuse |
    • pdizzle

      Learn about the scientific method. Theories are proven. Hypotheses are not. If you are a global warming skeptic, be aware the the vast majority of climatologists disagree with you. And they have analyzed the evidence. You probably have not.

      August 30, 2011 at 4:07 pm | Report abuse |
    • Roy

      Your right. Lets start with getting rid of establishments with no proof at all. Like religion.

      August 30, 2011 at 4:08 pm | Report abuse |
    • NDirish

      you're so right. policy should be based on religious rhetoric!

      August 30, 2011 at 4:10 pm | Report abuse |
    • jman57

      weather != climate

      August 30, 2011 at 4:14 pm | Report abuse |
    • Josh

      You can measure the temperature of the Earth, and see that it is warming. You can measure the CO2 level in the atmosphere and see that it has grown exponentially in the past century. That is not guesswork, it is data - it is fact. Science takes that physical data, feeds it into models, and makes predictions. Sometimes those predictions are inexact because models are not exact, but if models predict that in fifty or a hundred years climate change is going to make our little blue planet less habitable, I will certainly pay attention.

      August 30, 2011 at 4:23 pm | Report abuse |
    • Ram v

      I agree with you if you can not predict for 4days correctly why scare the people for 100 years

      August 30, 2011 at 4:46 pm | Report abuse |
    • gremlinus

      Considering how closely they can model hurricanes even given the computational challenges (considering the sizes of hurricanes and the ocean compared to the coastline) I think that's a pretty d@mn good reason to listen MORE to climatologists about global climate change. That being said, maybe you should learn more about what's involved in these sciences.

      August 30, 2011 at 6:59 pm | Report abuse |
  5. Brad

    i love how weather men think they know everything but they know as much as joe blow

    August 30, 2011 at 3:59 pm | Report abuse |
  6. Luke Brown

    Americans need to accept the fact that repeated budget cuts in Washington have consequences. We no longer have the capacity to monitor and track hurricanes. Short-term cuts in agency budgets end up costing Americans far more in the long-term.

    August 30, 2011 at 3:59 pm | Report abuse |
    • Cali

      Be real. We never had that capability.
      Throwing another billion or two into the industry will not help.
      Cut the waste!

      August 30, 2011 at 4:16 pm | Report abuse |
  7. mark

    The tea-party (there is no Republican party anymore – miss them compared to the baggers) says the NHC, EPA, and other climate and environmental agencies should all be eliminated. "Private enterprise can do the job better." And to their best interests with nobody to catch them.

    August 30, 2011 at 3:59 pm | Report abuse |
  8. Nini

    Missed the mark by being less of a storm??? May have produced less wind than expected but I don't think you can convince the residents of Vermont that this was less of a storm. Very little was ever mentioned about the rain that would be produced from the westerly side of the hurricane....everyone was too concerned about the coast line and the wind on the east side.

    August 30, 2011 at 3:59 pm | Report abuse |
  9. sam

    @indiarocks i can't believe how pathetic you are bashing americans and trying to group us all together i don't care what country your in you still have people who do everything you just posted how mindless and pathetic are you and for what was predicted for the hurricane you can't predict or control mother nature just as much as you can control a person and our forecasters do the best they can to help us out so stop complaining that it wasn't as bad as they thought and be happy the last thing we need is another tragedy and more people dead

    August 30, 2011 at 4:01 pm | Report abuse |
  10. Peter E

    Actually, the prediction was not off in destructiveness, considering that while the maximum winds declined somewhat, in turn Irene grew to epic proportions. This is because the central pressure remained low. This central pressure (<950mb) would normally would have been typical of major hurricanes, those that are of average size.
    So while the intensity of winds, and hence destruction wasn't that of a major hurricane, the total damage was similar anyway because Irene made up for it with much wider area coverage. The cost, and the millions of people left without power is quite similar to a major hurricane's effect. So the predictions were actually right on in terms of destruction similar to a major hurricane.

    August 30, 2011 at 4:01 pm | Report abuse |
  11. Justin

    I think people are being way too harsh on the forcasters. Even with all of the advances in technology that we have, weather forcasting is still a science in its infant stages. Let's not forget the price people pay for underestimating a storm. Post-Katrina, there's no more fooling around when it comes to hurricanes. That storm was severely underestimated, and it cost nearly 2,000 people their lives. Even a category 1 storm is extremely dangerous. It might not sound like much, but I had a 200 year old tree that stood 150 feet tall in my yard that snapped like a twig under the pressure of category 1 winds. I'd rather be over hyped about a storm and stay safe than to be lulled into a false sense of security and end up dead.

    August 30, 2011 at 4:03 pm | Report abuse |
  12. Robin

    Everyone needs to stop saying they "missed the mark" or that the storm was "too much media hype". I heard this a lot from New Yorkers in interviews online and on the news. As someone who lives in Richmond VA, and saw the devastation here, personally, and the storm just clipped us, I'm furious at these idiotic comments. Imagine being on the coast, or Vermont, or NJ.... People died. Lost homes. Are out tens of thousands of dollars because of the damage. Businesses weren't able to open. The center of the universe is NOT new york city. And calling it hype because of a +/-10-20mph wind speed or eye-wall landing city variation because of some "category" rating is rediculous. It was a HURRICANE people! Instead of criticizing the tiny details about the prediction, path and wind speed (it's mother nature, it can't be predicted), we should be grateful we're here and that it wasn't worse than it was. And pay attention, because here comes another one.

    August 30, 2011 at 4:04 pm | Report abuse |
  13. Jim

    I have a large tree down in my back yard. There is still people in the Philly area without power. It was destructive enough. They did the right thing and told people what they needed to hear. If they had said the store would loss some of its power and not be as bad more people whould have stayed down the cost and if it did stay as strong or strenthen then people would have called for their heads.

    August 30, 2011 at 4:04 pm | Report abuse |
  14. mdubbs

    The only reason so many people are complaining is because the storm was weaker when it hit New York than expected, and the majority of people from New York City are cynical crybabies, so all they want to do is complain about it. Take a trip down to the coast, or where it actually made landfall, if you want to see how devastating it actually was. Parts of the Outer Banks were literally separated from the main land, people were stranded, and even up as far into Philadelphia, tornadoes and heavy winds destroyed homes and knocked trees into homes. NYC and all the people there can keep complaining, maybe they will get what they ask for with this next tropical storm coming...

    August 30, 2011 at 4:04 pm | Report abuse |
  15. Limbaugh is a liberal

    Yes, thanks to the blasphemy of science, the incompetence of predictions, and the lack of prepardness of residents and authorities nature once again triumphed by killing tens of thousands of Americans, just like it used to a century ago.
    What? Thousands didn't die? Prepardness and predictions were effective? Science accurately predicted the path and hence saved millions of people? Um... It cannot be science... It's... it's... You are ugly!

    August 30, 2011 at 4:05 pm | Report abuse |
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