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. Columbus

    It would appear it's a little humbling to think we know so much, but that we still have much to learn. The real world is still quite complex and wild, it doesn't fit neatly into a computer program and perform predictably. This is a lesson to all the "kids" out there who think everything is explained by an app or the weather channel, you still need common sense to survive.

    August 30, 2011 at 3:45 pm | Report abuse |
  2. John

    I really, really dont understand this. We learned in school that New York city is in a Hurricane shadow (As are most oother Atlantic ports like Jacksonville, Boston, Philly, Charleston, Savannah. This means that if the hurricane hits them directly, that means they would have had to either go over land if they are curving to the NE. So naturally N.C and Long Island can get hit with intense storms, but other areas cant. For example to hit Jacksonville with a NE curve you would have to travel 100's of miles over Florida.

    What has changed?? There has never been a major hurricane that has been able to enter the Hudson river area because its got 100's of miles of land to the South. It could only enter strong with a very very strong NW push which is impossible.

    Can any of these weather people just for a minute show us a scenario where New York could actually get hit more than a Category one on the west side and force a storm surge into the harbor?? No its impossible....thats why I stayed put in my apartment on the river.

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

      I'm sorry, but that is complete bullsh*! New York has INDEED been directly hit by strong hurricanes in the past and sustained significant damage! There is no such thing as the "New York Hurricane shadow", it is a myth! You need to look up the weather history of New York! Some of the worst years were 1938, 1893, 1849, 1846, 1788, 1693, 1438 ...

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

    It isn't any more complicated than this: "Hi, I'm a self-annointed meteorologist "expert" (undergraduate and graduate studies). I will predict a catastrophic outcome, and if it comes true I will be able to add my accuracy to my resume and generate immensely more income. If it does not come true, I merely omit my inaccuracy from the resume, and no harm done. Right?

    August 30, 2011 at 3:45 pm | Report abuse |
  4. A God Fearing Muslim Woman

    In before something about HARP and some other bat chit propaganda.

    August 30, 2011 at 3:47 pm | Report abuse |
  5. Zach

    Not bad at all? I live in Vermont and whole towns are gone. Give me a break.

    August 30, 2011 at 3:47 pm | Report abuse |
    • Yes I have one

      They're talking about intensity at landfall, not the amount of moisture it's carrying

      August 30, 2011 at 3:52 pm | Report abuse |
  6. rd

    I think it was weak because people were praying. God hears prayer. That is my take anyway.

    August 30, 2011 at 3:48 pm | Report abuse |
    • Chase

      God also hears you fart.

      August 30, 2011 at 4:01 pm | Report abuse |
  7. SC Native

    Why would anyone complain that it was less intense than predicted? Crazy!

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

      I'm with you. I don't get it. So they were off... I think it would have been worse if they said it was a Category 1 hurricane and came in at Category 3...

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

      I thought the same. I feel like they are complaining that it didn't cause enough damage. There is way too much damage as is, but I guess it would've been more entertaining to talk/write about a Category 3 or 4 that would destroy skyscrappers in NYC and level houses along the coast.

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

    Oh, I know why! Because hurricanes are unpredictable and the best experts can do is an assesment of what the most likely scenario will be based on the data they've collected, and history. What else could they give us? Just think what we would be saying if the threat had been down played and an even greater disaster struck. They just can't win, can they? Those lucky enough to have escaped the worse of the storm should be grateful, not ranting about having their lives temporarily disrupted. It's nature, you know, comes with living on Planet Earth. (Thus far...)

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

      The reason that they cannot be predicted is because the world belongs to Him, not some scientist.

      August 30, 2011 at 3:54 pm | Report abuse |
  9. Mike

    Overestimate this – 53 hours and counting without electricity. Just cus Battery Park didn't get washed into the ocean doesn't mean the storm was a flop. NYC center dope. Open your eyes. Mass, Conn, and VT (especially VT) were destroyed by this storm.

    August 30, 2011 at 3:49 pm | Report abuse |
  10. BobJones

    All you whiners slept through your elementary school science classes and now you have the gall to criticize professional weather forecasters and scientists (forget about your worthless pretty-face TV "weathercasters"; they don't count)? If you don't like the job they're doing, feel free to make your own global forecasts since it's so easy, but don't whine when you get your family killed because of your crappy decision to stay in a flood zone. Now go back to being ignorant while the rest of us smart people try to improve the science of meteorology.

    August 30, 2011 at 3:49 pm | Report abuse |
  11. patriot1942

    I think the major disconnect in tropical related weather reporting is a disconnect between the National Hurricane Center and the mainline media outlets. I've lived on the Gulf Coast the majority of my life from Florida to Texas and all states in between and the hurricane forecasting center is much better at forecasting as the have been in prior years. How the information used to what level is is exacerbated by the mainline media, state, and local governments is not the doing nor the fault of the hurricane prediction center. I use NOAA forecasting's website exclusively and my own common sense to make my decisions as to how to protect myself, my family, and my property.

    August 30, 2011 at 3:49 pm | Report abuse |
  12. ThemBones

    The Atlantic Ocean starts to get very cold once you get into the northern states area. I was at the beach in Rhode Island southern tip just 1 week ago...and that water was COLD. Being from Texas and seeing how some of the monsters hurricanes pickup steam once they enter Gulf of Mexico, I wasn't too worried except for falling trees.

    August 30, 2011 at 3:50 pm | Report abuse |
  13. Albert

    We will never know the effect on lives saved or lives lost due to the fact that predictions overstated the category of the storm. Overstating category may cause loss of life due to unnecessary evacuations, and economic loss due to over-reacting... but for this storm it seems it was unusually destructive for a CAT 1 .
    Maybe, calling it a CAT 3 helped save some lives but there is no way to verify that.
    Maybe some survived because they stayed off the roads, we will not know

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

      I'm sure that the President will have some number to offer as lives "saved or created"......

      August 30, 2011 at 3:57 pm | Report abuse |
  14. Hal

    NO ONE will ever predict the weather accurately. It is not humanly possible even with computers. We are a limited species. Not to make any excuses for meteorologists.

    August 30, 2011 at 3:51 pm | Report abuse |
  15. Jo Jo

    Why does CNN feel the need to explain the misstep? Why not just admit there are certain things on this earth man has absolutely no control over and the whether just happen to be one of them. Those who think otherwise are delusional. Science can only go so far; that is why they were off the mark with this one and will continue to be in the future. I'm sure they did their best but how can you predict something that's unpredictable? I don't fault them however, for their effort. If they were correct and no one was warned, we could have had another Katrina disaster. So, for those who are complaining about them missing the mark and having all those people evacuate, I say it's better to play it safe than sorry.

    August 30, 2011 at 3:53 pm | Report abuse |
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