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. Dan

    Actually the reason for the missed mark is very simple. Prior to Hurricane Andrew the NHC would calculate surface winds as low as 70% of flight level reported by hurricane hunters. The NHC has since used Andrew as an excuse to report surface level winds at 90% of flight level which is honestly quite ridiculous. Not once have I seen observations (since the change) that came anywhere close to what the NHC reported as maximum sustained winds. Systems are being classified as tropical storms today that are barely depressions. Systems are being classified today as huricanes when they are in reality nothing more than tropical storms. Take whatever the NHC reports as the maximum sustained winds and subtract 20%. That will give you a more accurate representation of the storm strength.

    Don't believe me? Pay very close attention to the next storm at landfall and look for observations from buoys and other stations. You'll find nothing better (sustained) than 20% off what the NHC reports. It is hard to find a wind gust that reports as high as the NHC sustained number.

    August 30, 2011 at 2:59 pm | Report abuse |
  2. slider

    They try their very best to present the truth. I remember Anderson Cooper standing in a flooded ditch in Texas to show how high the water was. Standing outside the ditch wouldn't have been as impressive.

    August 30, 2011 at 3:01 pm | Report abuse |
    • candid_one

      When the water outside the ditch was running into the ditch–which usually has little or no water, his frame of reference was more realistic than yours.

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

    Just curious: how much more devastating did this storm need to be before people would have been happy with the prediction?

    August 30, 2011 at 3:01 pm | Report abuse |
  4. Amy

    How wonderful that you grouped all Americans together. Thanks a bunch.

    August 30, 2011 at 3:02 pm | Report abuse |
  5. mjenks

    I'd say it's all a matter of perspective. Would narcissistic New Yorkers say the hurricane was overblown? Probably. However, at the same time residents of Vermont would say the hurricane wasn't hyped enough! The world doesn't end beyond NYC or even Philadelphia or D.C.

    August 30, 2011 at 3:03 pm | Report abuse |
  6. Fred

    Very sad when a Cat 1 causes 10 Billion in damage. Can you imagine if it was a real Hurricane...

    August 30, 2011 at 3:04 pm | Report abuse |
    • BillInLA

      A "real" hurricane that was smaller in size would likely have caused less damage. The intensity is only one source of damage; amount of rain is another. the 11th most damaging hurricane in the history of the US was a category 1 - mostly because of flooding. That was Agnes in 1972. Very similar hurricane - large but weak in wind speed.

      August 30, 2011 at 3:13 pm | Report abuse |
    • candid_one

      Hurricanes don't cause most of their damage with wind power. For days, the National Hurricane Center and FEMA warned about the water. Storm surge along the coast and inland freshwater flooding are the real damaging components. Vermont is an inland landlocked region. Floods took out bridges that had stood for more than a century. One town lost a cemetery that went back two centuries. In some villages, this flooding did more damage than the Joplin tornadoes, took away everything, worse than the Fukushima tsunami. The rains did this; didn't need wind.

      August 30, 2011 at 3:26 pm | Report abuse |
  7. PaulMc1981

    "Self-righteous"? "Obnoxious"? "Egocentric"? You're a troll, and your own words describe you quite well. What's worse is that you make all Indians look bad. I'm an American citizen of Indian origin, and I'm proud to live in this (mostly) free and democratic society.

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

    A lot of the problem lies in the fact that weather forecasters don't have direct access to the public anymore. Their predictions are now filtered through weather 'personality' talking heads. I'd bet something important is being left out because of time constraints or subject matter deemed too complex for public consumption. I long for the day when the local TV weatherman was a true meteorological geek and the homeliest person on TV. You don't even get that on the Weather Channel anymore.

    August 30, 2011 at 3:05 pm | Report abuse |
    • Margroks

      But that's not really true. The weather channel has lots of meteorologists and several who specialize in wind events like hurricanes. They were as accurate as possible given the amount of data and they did their job. I don't understand why some people are so unhappy that Irene wasn't eaxctly what was predicted. They should be grateful.

      August 30, 2011 at 3:17 pm | Report abuse |
    • BillInLA

      Absolutely false on all counts. One, weather news was always filtered through the news stations on TV. If their weather reporter was a meterologist, it was just one meterologist filtering the work of others. Two, you and the weather experts can interact. You just have to go to their websites. That was not possible before the Internet. The fact that you don't want to go to the NOAA website or that of someone like the brilliant Dr. Jeff Masters is purely your choice about what you watch or read.

      August 30, 2011 at 3:18 pm | Report abuse |
  9. jon

    It wasn't the forecasters hyping up the store it was the media as usual. CNN had a big part it the hype

    August 30, 2011 at 3:06 pm | Report abuse |
  10. Al from Florida

    Actually Irene was a hurricane many years ago. She was supposed to hit the west coast of Florida. The local weather man Bill Kamal told then Hurricane Center Director that he saw a slight jog to the right, meaning it looked like it was going to hit the east coast of Florida and he asked that the NHC issue a Hurricane Warning for Ft Lauderdale & Miami. He refused. Guess what.. it came down 1-75 right into Ft Lauderdale/Miami as a Cat 1 with no preparations. I drove home in it and 85 MPH Sustained winds is not a joke. I was dodging trees falling and powerpoles coming down all over the place. When I got to my house i was standing in about 1 foot of water and I had to fight the sustained winds to get back into the house.

    August 30, 2011 at 3:07 pm | Report abuse |
    • Al from Florida

      http://en.wikipedia.org/wiki/Hurricane_Irene_(1999)

      August 30, 2011 at 3:09 pm | Report abuse |
  11. Wharf Rat

    This whole thing reminds me of an old stand-up comic routine I saw many years ago. The comedian was speaking about local news, and how the Sports Guy would always mock the Weather Guy ("Got that one wrong again, didn't ya Chuck?!"). His hypothesis was that the Weatherman should stand his ground. It went something like this: "You idiots reports what already happened... I'm trying to predict THE FUTURE!"

    Shut up and just be glad you're safe, folks. Leave the weathermen alone, unless you've got something better to help them tell you whether or not you're going to be wet on certain days. Predicting the future isn't all that easy, as we've seen.

    August 30, 2011 at 3:07 pm | Report abuse |
    • BillInLA

      Agree.

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

      Classic !!!!

      August 30, 2011 at 3:19 pm | Report abuse |
  12. Hasselhoff

    People were actually mad it was a tropical storm what do you want more damage? Can't please EVERYONE!

    August 30, 2011 at 3:08 pm | Report abuse |
    • Cindy from NC

      The problem is we have been so desensatized by TV and catastrophic movies and do telethons for really major diasters that this seem like nothing to people, which is sad becasue lives were lost, peoples homes destroyed and towns wiped off the map. Had the weatherfolks not made a big deal, I think we would have seen a lot more deaths and we would have been complaining why didn't you tell us or why weren't we prepared.
      I woke the next day and said this was nothing until I turned on the TV and saw towns underwater which gave me a reality check. Thank you god becaues that could have been me.

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

    Don't worry Katia will do more damage were ever that one hits i think it's going to be a lot bigger.

    August 30, 2011 at 3:09 pm | Report abuse |
  14. Jared

    Well....acutally you definitely accurately decribed 99% of our politicians.

    August 30, 2011 at 3:10 pm | Report abuse |
  15. Scott

    Is it just me or was it very clear that there was cold dry air pushing the hurricane from the south. Maybe it was the lack of rain an intensity in the entire southern section of the storm?

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