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. ralk

    Gee...the libs try to make this into the black cloud over this country...it turns out to be a tropical storm...it is bad enough yes but they always try to create fear and garbage like that when it doesn't need to be...then the lib media tries to back track to see what really happen...and never say much after they put their tails between their legs and try to go hide somewhere...when the big one does come...they will be back to make it sound worse that it really will be again. Idiots.

    August 30, 2011 at 2:45 pm | Report abuse |
    • Ralf The Dog

      Dude, you have half the brains of a mouse. Hurricane strength is based on something called a chaotic system (or an iterated system) where very small changes in input data can have very large changes in the results. Chaotic systems are very hard to predict by definition. Irene had the potential to be a much stronger storm. The probabilities were that it would be a much stronger storm. We just dodged a bullet.

      August 30, 2011 at 3:06 pm | Report abuse |
  2. Gr8isHE

    They won't ever be able to get it right because you can't predict the wind...only God controls that "And the LORD changed the wind to a very strong west wind, which caught up the locusts and carried them into the Red Sea. Not a locust was left anywhere in Egypt – Ex 10:19"

    "Then Moses stretched out his hand over the sea, and all that night the LORD drove the sea back with a strong east wind and turned it into dry land. The waters were divided, Ex 14:21"

    "Now a wind went out from the LORD and drove quail in from the sea. It scattered them up to two cubits deep all around the camp, as far as a day’s walk in any direction. – Nu 11:31"

    "when suddenly a mighty wind swept in from the desert and struck the four corners of the house. It collapsed on them and they are dead, and I am the only one who has escaped to tell you! – Job 1:19”

    "When he established the force of the wind and measured out the waters, Job 28:25"

    "He let loose the east wind from the heavens and by his power made the south wind blow. – Psalms 78:26"

    "He makes winds his messengers, flames of fire his servants. – Psalms 104:4"

    "lightning and hail, snow and clouds, stormy winds that do his bidding,- Ps148:8"

    "Who has gone up to heaven and come down? Whose hands have gathered up the wind? Who has wrapped up the waters in a cloak? Who has established all the ends of the earth? What is his name, and what is the name of his son? Surely you know! – Ps 30:4"

    I could go on but the last verse says it all and by now you get it...At least I pray you do.

    August 30, 2011 at 2:45 pm | Report abuse |
    • Weak Sauce

      "I could go on but the last verse says it all and by now you get it..."

      ..Get that you are a religious nut? sure.

      August 30, 2011 at 2:53 pm | Report abuse |
    • Gr8isHE

      Weak Sauce, If that's what you want to call a believer of the word of God then I'll take it! Thanks

      I'll also pray YOU will become a believer or "religious nut" as you would call it.

      August 30, 2011 at 2:56 pm | Report abuse |
  3. mak

    Better safe then dead

    August 30, 2011 at 2:46 pm | Report abuse |
    • jackie

      well said

      August 30, 2011 at 2:52 pm | Report abuse |
    • PaulMc1981

      Yup.

      August 30, 2011 at 3:02 pm | Report abuse |
  4. Truth

    So it comes down to human beings disgracing one another and judging each other. Well, all aside I must say well done to the people who tried to do whats right and protect others from what could of happen. We look at the world as it is predictable, well..its not. No technology is gonna tell us when things will happen on this day at this time or how intense, but it will guide us to a bit of safety. Mother nature has its own plan. And the best as a nation ,as a whole we go out and help one another to survive.
    Thank you for trying and being there for those who were helping, and to those who died during this tragic storm, peace be with you and the families.

    August 30, 2011 at 2:47 pm | Report abuse |
  5. Bill

    Maybe they should finally invest in real-time weather prediction from Airdat. http://www.airdat.com

    August 30, 2011 at 2:49 pm | Report abuse |
  6. knitpickin

    Personally, I prefer the accuracy be in where storms go rather than how strong they are. It amazes me that the course of a storm is so accurate to the predictions.
    To me, if I know a storm is coming my way, I prepare for a worse case scenario rather than the "that's good enuff" mentality.
    Hats off to the guys and gals at the NHC. Your work saves lives.

    August 30, 2011 at 2:49 pm | Report abuse |
    • PaulMc1981

      Right on.

      August 30, 2011 at 3:00 pm | Report abuse |
  7. Grumpster

    This was an easy one. Having been at Rehoboth and Ocean City MD the weekend prior, and experiencing 1st-hand the cool water temperatures, I could have forecast it wasn't going to be that big of a deal there. Nobody bothers to do hands-on any more, just look at the models. I harrassed a Seattle weathercaster and eventually bet him I could do a better job than him by sticking my head out the window in the in the evening and sending him my prediction for the next day. Me...43% accuracy...him, 26%. He begrudgingly made a snide comment on air (directed at me) about those of us who stick their heads out windows and how unpredictable things are after the 30-day bet was lost by him.

    I also predicted the westerly track vs the track along the coast since the front that would hold it out was obvioiusly moving too far away to influence it toward the coast. Again...my track won. I had basic meteorology class 25 years ago in college, didn't use tools except looking at the maps available online and radar images.

    The hype on this has a sole purpose of RATINGS and if you believe otherwise, you may want to buy the bridge I have for sale.

    August 30, 2011 at 2:49 pm | Report abuse |
    • Mike

      You didn't use tools, eh? How do you think those maps and radar images were produced? You used other people's instruments, observations, and calcuations and then took sole credit for the conclusion. This is arrogance.

      August 30, 2011 at 3:05 pm | Report abuse |
  8. Real truth

    The real truth is that the White House didn't want anything happening that people weren't warned could happen so they forced the National Hurricane Center to "predict" a much stronger storm. This way the White House would not have a "Katrina" on their hands.

    August 30, 2011 at 2:51 pm | Report abuse |
    • Leroy

      How dare you speek about Obama like that! He's the bestest thing that we have happened to us. I can't wate until he gets 4 mor years and I get more money in my gov check. He wouldn't make people lie. He would only tell truth and save many many peoples life. You lie, not him!!!!

      August 30, 2011 at 2:55 pm | Report abuse |
    • waswaiting4it

      Ha! Was waiting for this to somehow be pinned on the administration. Been watching Fox this morning?

      August 30, 2011 at 3:02 pm | Report abuse |
  9. Joel

    It amazes me how many elementary-grade students (or grade-equivalent people) are allowed on message boards like this by their mommies.

    August 30, 2011 at 2:53 pm | Report abuse |
  10. Squid

    These "forecasters" need to be arrested over this debacle. People were forced to evacuate because they couldn't correctly predict

    August 30, 2011 at 2:54 pm | Report abuse |
    • PaulMc1981

      Yes, because weather forecasters must be able to predict the weather with 100% accuracy, all the time. Not.

      August 30, 2011 at 3:06 pm | Report abuse |
  11. lol

    coming from india thats funny

    August 30, 2011 at 2:56 pm | Report abuse |
  12. PaulMc1981

    I don't believe it's fair to expect weather forecasters to get it right all the time. Hindsight is ALWAYS 20/20. What if they "under-predicted" the intensity of the storm, and it killed a whole bunch of people? Americans would be up in arms, people would want to sue, etc. It always makes sense to be prepared, based on the best available evidence. Besides, those of you who know anything about the science of meteorology know that prediction of nonlinear, chaotic systems is extremely difficult, even with our best mathematical models.

    August 30, 2011 at 2:57 pm | Report abuse |
  13. Kevin

    As a Florida resident, I depend on the storm forecasts in our area. I find them to be quite accurate. They give us plenty of time to leave town if need be. This storm was large and had killer potential, over 30 dead & $1.5 billion in damages. I think they did a good job predicting the storm.

    August 30, 2011 at 2:58 pm | Report abuse |
    • Al from Florida

      Well said!

      August 30, 2011 at 3:12 pm | Report abuse |
  14. Amer Man

    I have to admit . . . reading the comments posted has become much more entertaining than the articles themselves.

    August 30, 2011 at 2:58 pm | Report abuse |
  15. oysta

    Whether the wind speed is 90 or 110 mph shouldn't really matter when you think about the fact that EVERYBODY hit by this thing knew more than a week in advance that they would be affected. The forecasters do a great job. Without them, we would be clueless until the thing was on top of us. Thank you to the scientists who devote your lives to studying these things.

    August 30, 2011 at 2:58 pm | Report abuse |
    • PaulMc1981

      Well said.

      August 30, 2011 at 3:14 pm | Report abuse |
    • gelbstoff

      Absolutely! I grew up in the Caribbean and I am old enough to remember the times when we only knew that there was a hurricane that may or may not hit us. Now the trajectories are often predicted with errors smaller than the eye of the storm.

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