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. AG1969

    If they got the trajectory right, then why was Vermont so ignored? I thought I heard that the course changed the projected path once it got to New England? If not, then it was due to sweep over that state as well from the very beginning. So, was VT not included simply because it was landlocked or were their emergency officials notified and they decided to take a "wait and see" approach?

    I grew up in VT and still have family there, so yes, this is of particular interest to me, however, I do feel for everyone affected by this storm. Even at a Cat 1, there was still a lot of damage. My thoughts and prayers are with every one of them.

    August 30, 2011 at 3:24 pm | Report abuse |
  2. bailoutsos

    Extreme prediction and people still stayed. How many died from a tropical storm?

    August 30, 2011 at 3:24 pm | Report abuse |
  3. Bud bundy

    This Zarella guy is a moron. Must come from a stupid family. Tell vermont they overestimated the storm and it wasn't bad. Succarella tua mama!!

    August 30, 2011 at 3:24 pm | Report abuse |
    • bwp88

      But that's just vermont. Nobody was talking about vermont. What's vermont?

      August 30, 2011 at 3:35 pm | Report abuse |
  4. babaelf

    Rather than call them direct acts of God, which language offend some people, we’re morons of we don’t understand that Nature’s law is balance. Constant adjustments are made between heat and cold, light and rain, sound and the elements. There are powerful conscious Energies whose provenance in the entire creation is a divinely mandated commitment to keep nature’s elements in balance.
    With equilibrium, the process of evolution flows smoothly. But man’s actions are now so unnatural that nature has been deeply disturbed, resulting in destructive chaos, widespread immunological breakdown, environmental degradation and toxic chemical pollution penetrating the very DNA of human, animal and vegetable organisms – nature totally reeling and out of balance by man’s drunken lack of environmental awareness.
    As a defense, nature tries to adjust itself. Floods, tsunamis, droughts, volcanic eruptions, tornadoes, hurricanes and even plagues are some of the ways by which nature’s immune system seeks to shout out – to cleanse and balance itself on earth. The reaction of nature is a blindingly flashing red-light that man’s actions are unnatural; that he need be true to his inner demands, which acted upon automatically set a proper balance within human consciousness and adjust the physical conditions in the entire creation around him. When creation is overwhelmed with such unnatural processes, it seeks divine intervention; what more can it do?

    August 30, 2011 at 3:24 pm | Report abuse |
    • Andrew

      I sincerely doubt you have any idea what the word 'energy' actually means in any robust context, and further, nor do I believe you can provide any evidence to support your blind new age assertion. You could cite global warming, but things like us changing DNA casing tornadoes or hurricanes? Uhh, right.

      August 30, 2011 at 3:46 pm | Report abuse |
  5. dan

    I live in North Carolina and just want to thank you for getting it right. I would rather be told a CAT 3 aget a CAT 1 rather than the reverse.

    August 30, 2011 at 3:25 pm | Report abuse |
    • veggiedude

      I'm just impressed they can predict the path.

      August 30, 2011 at 3:39 pm | Report abuse |
  6. fearless68

    I thought they did a great job forecasting the storm. Of course they will never be 100% accurate because a lot of times mother nature has her own plans. They accurately predicted the path and eye of the storm at least 3-4 days in advance and was almost right on. It's also a good thing that there was a lot of hype because it probably saved many lives.

    August 30, 2011 at 3:25 pm | Report abuse |
  7. Diana

    With the damage that was done, everyone should be damn glad it wasn't any stronger than it was. For those areas who are used to the hurricane drill, may have been a let down, but for those who have never experienced it, it was bad enough.

    August 30, 2011 at 3:25 pm | Report abuse |
  8. Chappy

    Question: Is anyone racing to go become a forecaster? Not really! we are good at complaining when they get it wrong but, not as quick to step in their shoes. They still serve a purpose. Cut them some slack!

    August 30, 2011 at 3:27 pm | Report abuse |
    • Steve

      @Chappy What? We have to be willing to be one of them before we can criticize? That's going to make any kind of critique or analysis in life really time-consuming and complex – I've got a lot of new careers to take on.

      August 30, 2011 at 3:45 pm | Report abuse |
    • Yacker

      Cut them some slack, are you nuts? With all their equipment, training, years of on the job, etc,etc and they couldn't say that this hurricane was not going to lose intensity. It's common knowledge that when a hurricane starts going over a large land mass it will "come apart". That's why you don't see hurricanes inland. As far as predicting the path. Please! knowing the barometric pressure around it will tell you where will more than likely go.

      August 30, 2011 at 3:58 pm | Report abuse |
  9. Chris

    I had been tracking the storm very closely because I was concerned about my vacation plans. Looking at the past history of hurrianes, looking at the physics involved when the storms bands get over land and looking at the size of the storm and the amount of time that the bands would be over land before the eye would arrive it was fairly obvious to me that it would do exactly as it did. I had emailed several people explaining what it would do before its outerbands ever made landfall. The forecasters need to turn off the stupid computers and look at what is going on!

    August 30, 2011 at 3:29 pm | Report abuse |
    • Ken

      +1 on that, Chris, in addition, I caught a water temperature map that showed much cooler water above Hatteras early
      on in the coverage, and then I knew it would be a Cat 1 or less when it hit the NE/Long Island shore. Knowing the history
      and characteristics of the '38 Hurricane helps to understand why. I live in Vermont, and am appalled by the lack of accurate forecasting on the amount of rain here predicted here.

      August 30, 2011 at 3:58 pm | Report abuse |
    • Amused

      OOoooooh! So you guessed right this time, huh? Well goody for you – try your luck in vegas sometime, then you might have some appreciation for what REAL forecasters actually do and maybe learn to be a little less full of yourself!

      August 30, 2011 at 4:00 pm | Report abuse |
  10. ipmutt

    More Bull from mainstream media. This was media driven hysteria with one goal in mind. An audience. Entertainment at it's most destructive. Now they will start on the next one and get the name as close to Katrina as they can.

    August 30, 2011 at 3:32 pm | Report abuse |
    • Columbus

      Hey, look at that, Katia! You're right.

      August 30, 2011 at 3:49 pm | Report abuse |
    • Amused

      You are so full of manure !!! These predictions came directly from the National Weather Service's Hurricane Center. They did their very best to make an accurate prediction of path and intensity so that they could save as many lives as possible ! They are not perfect, but they most certainly saved hundreds of lives by erring on the side of caution! It is impossible to be 100% accurate when predicting weather events, but they did an impressive job of coming as close as they did! I suppose you think you could do better just like Mr. know-it-all Chris above! Yeah, right! ...

      August 30, 2011 at 4:13 pm | Report abuse |
  11. Jeff

    Tell that to the 38 people who died!

    August 30, 2011 at 3:33 pm | Report abuse |
  12. JanieJane

    Over the last 48 hours, I have been assigned to shelter operations conducted by the Red Cross. In this time, I have seen the remnants of homes that have been swept away. I have seen river-banks filled with goods that had been swept from homes, and I have met victims who have lost everything. In the conversations I have had with the hundreds of people that I have encountered, not one of them blamed the meteorologists. In fact, in the communities I have served in, I have seen the best of humanity. The communities are coming together to offer money, clothes, food and shelter to people who have become victims of this disaster. It is a natural disaster and it is short-sided to blame the media for being precise as in what predicting what Mother Nature will dole out.

    August 30, 2011 at 3:38 pm | Report abuse |
  13. detada

    Since when did weather forecasting become an exact science? I'm not upset about the forecast not being precise. I am more upset about the non-stop coverage and the endless scenes of reporters running around, constantly looking for severe wind gusts, pouring rain, rampant flooding, 50 foot waves and houses being washed down river. It was way overcooked.

    August 30, 2011 at 3:39 pm | Report abuse |
  14. Amyrica

    The credibility of the media reporting weather is seriously in question. So much over the top exaggeration of the actual event! Weather people standing in front of some medium size waves ranting on about how dangerous it was in the mid atlantic area, while kids played in the surf behind them. I live in Virginia Beach and didn't even lose power, and have seen very little damage. How can I believe what they tell me about Vermont or New York.

    August 30, 2011 at 3:39 pm | Report abuse |
    • Dave

      wow What a statement I pray that you never experience what the people of Vermont and the other areas affected are going through today. That is the nature of these type of event not everyone experience the same things that does not mean its any less dangerous. It just means you were lucky enjoy your luck and hope it never changes.

      August 30, 2011 at 3:51 pm | Report abuse |
    • AG1969

      I have friends and family in VT. It's not an exaggeration. Check out the open story accounts here on CNN or, if you are on FB, check out the WCAX page and read the stories and look at the pics of those living it.

      August 30, 2011 at 4:01 pm | Report abuse |
  15. Jerry

    I think too many people are confusing the MEDIA forecasts with the official NWS forecasts. The media hyped this all out of proportion, because that is the best way to attract viewers and boost profits. The NWS forecasts always emphasized the potential for flooding far away from where the center made landfall. They always state that a hurricane is not a point and not to focus just on that track. Once again, the private sector should take most of the blame here, the government forecasts were very good, even if the intensity forecasts were off a couple of categories. I see lots of headlines of flooding even today, exactly what was forecast.

    August 30, 2011 at 3:43 pm | Report abuse |
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