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.

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

    If the weatherman warns of tornadoes, run to the basement and you dont get hit. Do you blame the weatherman?

    August 30, 2011 at 1:30 pm | Report abuse |
  2. mark in nyc

    next time, let's underestimate so more people can DIE.

    August 30, 2011 at 1:31 pm | Report abuse |
  3. Victor

    Well folks to hear Michelle Bachmann putt it, did not matter what they said, GOD placed the storm, the intensity and the realize anyway. Be that the case the weather chanel folks should hold prayer circles instead of map and chat study.

    August 30, 2011 at 1:31 pm | Report abuse |
  4. deathwombat

    I don't understand why this is even news. First of all, Category 1 is not "the weakest". Below Category 1 are Tropical Storm and Tropical Depression. It's not as though Category 1 is a light breeze! They predicted that a disaster would occur, and a disaster occurred; why are we nitpicking about what category the storm was when it killed 38+ people, knocked out power to 4 million homes and did more than a billion dollars of damage? I could understand if they predicted a major hurricane and it was downgraded to a tropical depression before it made landfall, but it's not as though a Category 1 hurricane isn't a dangerous storm.

    What if they had predicted that it would Category 1 and it had been Category 3? People might not have heeded the evacuation order, or there may not have been evacuation orders, and many more people would have died. If they're going to err one way or the other, I'm glad they erred on the side of caution. It wasn't a Category 3, but it could have been. THIS IS NOT A SCANDAL!

    August 30, 2011 at 1:31 pm | Report abuse |
    • Hugo

      They want to blame somebody since they can't blame President Obama for a change. It's not like he sat on a hospital ship unitl 2 weeks after the storm had hit before sending it out.

      August 30, 2011 at 1:37 pm | Report abuse |
    • Michelle

      Hmmm Category 1 is indeed the weakest of hurricanes, which is precisely what he meant. The scale is 1-5, then below 1 is Tropical Storm and then Tropical Depression. When he said "weakest" he obviously meant within the scale for hurricane ratings, and Irene was in fact a Category 1 hurricane (THE WEAKEST OF HURRICANES) upon landfall. What part of that is confusing to you?

      August 30, 2011 at 1:46 pm | Report abuse |
    • AmazedinFL

      Michelle, I think you're still missing the main point–it was predicted that the storm would cause devastation, and it quite obviously did. So why make such a big deal out of the fact that it was a 1 instead of a 3? As far as I'm concerned, the forecasters still saved a lot of lives through the prediction, and I'd much rather have an over-estimation than an under-estimation. The over-estimation causes some loss of money and convenience, whereas the under-estimation results in the much more serious consequence of lives being lost that wouldn't have been lost otherwise.

      August 30, 2011 at 2:47 pm | Report abuse |
    • deathwombat

      @Michelle: It's not confusing to me, it's deceptive. You and I know that a storm has to be extremely dangerous before it reaches Category 1 status. The article doesn't say "weakest hurricane", it says "Irene came in at a Category 1, the weakest.", as though a tropical cyclone can be no less powerful than Category 1 hurricane.

      August 30, 2011 at 2:54 pm | Report abuse |
    • AmazedinFL

      Very true deathwombat. Ask the residents of Prattsville, whose town (one of many) was entirely destroyed by Irene. Calling a 'category 1 hurricane' 'the weakest' is pretty misleading, since the number '1' is pretty much entirely arbitrary. It makes it sound as if once the storm is below category 1 (i.e., a tropical storm) it's somehow categorically different, and something doesn't 'start' becoming a hurricane until it reaches category 1 status. In reality, both are cyclones, with a closed system of spiraling winds. The difference between the two is as little as a mile per hour of wind speed. It would be much less misleading to call EVERYTHING (including a tropical storm and a tropical depression) by the same name–since they're all cyclones in reality, and start the number 1 at the level of a tropical depression. By the time it reaches category 1 hurricane, it can already be absolutely devastating depending on what's around, so the 'category 1' name is truly misleading.

      August 30, 2011 at 3:27 pm | Report abuse |
  5. dee

    missed their mark... humm has anyone notice there is a town in NY that is flooded by Irene... not just one or two streets but the entire town. How about 30 something dead people. How about more than 1 million of people without electricity. ...hummm what about more than 1 billion in damages... what more do people want? ask that question to a family member that lost someone to Irene ...I'm sure they won’t agree with you on who forecast the weather and who said what...or who said too much or didn't say enough. It’s never enough..if you say too much is terrible if you say too little you horrific ... goodness
    by the way not everyone that die was caught surfing.. just saying

    August 30, 2011 at 1:32 pm | Report abuse |

    I luved this article, ty for posting it. I liked it 😀

    August 30, 2011 at 1:32 pm | Report abuse |
  7. Olaf Big

    He is just shooting BS. Sure for the people on the ground it is better if the storm turns out weaker than expected, but that's just a matter of chance and has nothing to do with the work of weather forecasters. They are just wrong say 40% of the time, and in half of those cases the storm turns out stronger than predicted, and in half of the cases it is weaker than predcited. If he is trying to say that they prefer to err on the side of caution and adjust their predictions uprwards than they are simply not doing their job.

    August 30, 2011 at 1:32 pm | Report abuse |
  8. Eric

    Ask Vermont if Irene was overhyped. Just because NY and Boston didn't get hit hard doesn't mean there wasn't devastation.

    August 30, 2011 at 1:32 pm | Report abuse |
    • Michelle

      Massachusetts got hit hard (Boston in the eastern part of the state was already known to not be in the path, western MA was). 600,000 without power, flooding damaged homes, countless downed trees, lost roofs, etc.

      August 30, 2011 at 1:49 pm | Report abuse |
  9. Fed Up

    I say screw the public. They all want to be so ungrateful and think they know better than those with a degree. The next time a hurricane comes across the Atlantic I say all weather forecasters walk out, let those who think they know it all decide their own fate. There are alot of variables that go into forecasting and most will never understand how daunting it is to get this right when there are lives on the line.

    August 30, 2011 at 1:33 pm | Report abuse |
    • Just Saying


      August 30, 2011 at 1:43 pm | Report abuse |
    • Aimer

      I second that Amen.

      August 30, 2011 at 3:19 pm | Report abuse |
  10. ed

    They miss the prediction because it's nature; it does what it wants. I have always thought the "hurricane Prediction" as in, "we are going to have 5 named storms, 3 CAT2 or better etc" is completely stupid. The fact that they are so far off this year is an example they they should only speak when they have empirical data, not forecasts using computer models. Computer models are guesses and no better than the FArmer's Almanac, which is generally more accurate.

    August 30, 2011 at 1:34 pm | Report abuse |
  11. Jose

    This is not news! Why is CNN making excuses for the Meteoroligists?

    August 30, 2011 at 1:34 pm | Report abuse |
  12. hippediva

    More CNN 'news' (i.e. fear mongering and nit-picking for fun and profit.)

    August 30, 2011 at 1:35 pm | Report abuse |
  13. Annie

    Your reporter spelled Charley'd think CNN would know well enough to check how to spell the name of such a devastating storm.

    August 30, 2011 at 1:35 pm | Report abuse |
  14. sharky

    Mother Nature is NOT predictable and anyone thinking they can really predict what will happen, well then call yourself God. Humans can only do so much, accept it. We are not omniscient, we can only do the best we can do especially when against natural forces. Plain and simple.

    August 30, 2011 at 1:36 pm | Report abuse |
  15. rubi

    yeah right, 24 hour news is supposed to put fear in anyone watch it

    August 30, 2011 at 1:37 pm | Report abuse |
    • njite

      I live in NJ and I was following the weather forecasts from CNN, weather channel and NJ12 and they were actually excellent. The only thing I was concerned was when we are the victims on the path of the hurricane, its not enjoyable watching someone sitting away from harms way talking aggressively of how the hurricane is going to cause destruction. They need to be more supportive of the poor people. But the hurricane was intense. I could not sleep and constantly monitoring the sump-pump, and the wind velocity was scary. My neighbors large trees were leaning on my house and one is almost chopped (like how a tree-cutter would chop it), and its about to fall (told the neighbor to get it taken down immediately). But the wind was scary and the rain was intense. Most people in my neighborhood flooded with multiple sump-pumps. I was lucky I had a good pitch and good french-drain.
      I give credit to the news channels, but please don't scare us. btw, the Eye of the storm never seemed to matter much as much as the rain bands around it, and the ones before it, more than the ones behind it. pretty impressive science, got to give credit. I feel bad when they say New yorkers don't care. but who cares about what the new-yorkers think. this is dangerous, I have seen how these cyclones ruthlessly kill people in Andhra Pradesh in India.. thanks again to the weather folks. good job..

      August 30, 2011 at 1:58 pm | Report abuse |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26