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. bobincal

    If you go to the National Hurricane Center web site, you will see their Maximum 1-minute Wind Speed Probability Table. It describes the probability of wind ranges up to 120 hours for any approaching storm. No meteorologist or computer model can say, with absolute certainty, where a storm will come ashore or at what strength.

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

    I think most people understand that forecasting can't be perfect. But with respect to whether or not the storm was "overhyped," I don't think the forecast was the issue. Even when the storm was forecast to hit New York as a Cat 2, CNN and the other networks kept running and posting stories about worst-case scenarios for a Cat 3 storm making a direct hit on NYC. By then, that was no longer the forecast scenario, but they just broadcast story after story about NYC in the path of destruction. Then, when the storm had clearly weakened and every update had it weaker still, people like Chad Myers kept insisting the storm had Cat 3 potential because of the pressure–just as quoted in this piece. The point is, even after it was clear the forecasts WERE wrong, the "hype" continued. This makes the news divisions–if not the forecasters–less credible. Meanwhile, there was very little discussion on Friday and Saturday of the dangers posed to areas East and North of NYC, and look what we're now seeing in Vermont. How informed, prepared and warned were they while the media focused on the impending NYC disaster that never came?

    August 30, 2011 at 2:25 pm | Report abuse |
    • Alex

      I think less emphasis needed to be placed on the winds after it clearly started weakening with more emphasis on the flooding potential because this storm had a TON of rain. That was the most impressive part of this storm – the way it crawled up the coast with spiraling rain bands.

      August 30, 2011 at 2:33 pm | Report abuse |
  3. Bill

    Part of why they consistently miss the mark with hurricanes is their obsession with the utterly useless Saffir-Simpson scale. This scale provides NO useful information that just giving wind speed doesn't. A hurricane is a multidimensional storm, and as long as the only use a unidimensional measurement to categorize it, they are missing the point. They need to look at not only wind speed, but size of the storm, speed of movement, etc. Little of the damage from Irene resulted from wind, most from the tremendous rainfall, so the fact that it was 'only' a tropical storm didn't convey the true danger to those poor souls in upstate NY and Vermont.

    August 30, 2011 at 2:25 pm | Report abuse |
  4. IndiaRocks

    Wonder why hurricanes occur mostly in America? Because Americans are uncultured, perverted, inhuman, hypocritical, obnoxious, immoral, egocentric, insensitive, self-righteous, beef-eating b@st@rds.

    August 30, 2011 at 2:26 pm | Report abuse |
    • Mark C

      Good god, you really are an imbecile. Hurricanes occur all over - they're just called cyclones or typhoons. India gets hit by a large number of them, diaper-head.

      August 30, 2011 at 2:29 pm | Report abuse |
    • Rob

      You must be American then, eh?

      August 30, 2011 at 2:31 pm | Report abuse |
    • ThatGuy

      Ah, Indiarocks, are you trying to hurt my feelings? That's cute.

      August 30, 2011 at 2:37 pm | Report abuse |
    • Troll Alert

      You've been trolled. Trolled: "unwittingly led into hopeless retaliation at blog intended to provoke for amusemen to a troll." Don't fall into that trap again. I won't always be here to save you.

      August 30, 2011 at 2:42 pm | Report abuse |
    • Troll Alert

      You've all been trolled. Trolled: "unwittingly led into hopeless retaliation at blog intended to provoke for amusemen to a troll." Don't fall into that trap again. I won't always be here to save you.

      August 30, 2011 at 2:42 pm | Report abuse |
    • ThatGuy

      I heard you the first time.

      August 30, 2011 at 2:44 pm | Report abuse |
  5. NipponReptilian

    Probably they intentionally misled people living there. It is obvious Irene was not Category 1. You had better check Intellicast.com radar yourself rather than you trust news agencies next time.

    August 30, 2011 at 2:27 pm | Report abuse |
    • Mark C

      Another moron heard from.

      August 30, 2011 at 2:33 pm | Report abuse |
  6. Dave B

    They were just about dead-on with the track over the last three days before Irene hit L.I. and CT. If a car is coming right at you at 50 mph, and gets to 100 feet away, whether it slams on the brakes or not (who knows?), you're most likely going to get hit. How hard depends on a lot of factors. Would you prefer that nobody says anything to you or pulls you out of the way, assuming the driver will stop? Even if he could stop, I'd like to be out of the way.

    August 30, 2011 at 2:27 pm | Report abuse |
    • Alex

      I agree, the track was extremely accurate, but the storm started to unravel before it reached NC. You could see that on the IR images. It became less "tight" (though it was always large). Still an impressive system nonetheless. It's not too often there is a Cat 1 storm crawling up the east coast.

      August 30, 2011 at 2:31 pm | Report abuse |
  7. clay

    way to stereotype and generalize a population of 300 million when you havent even been to this country. This is the kind of trash that should be expected from trolls like you. Do everyone a huge favor and stay in India.

    August 30, 2011 at 2:27 pm | Report abuse |
  8. Alex

    I actually don't think the contact with NC had much to do with the storm's impact. The problem was that it didn't make landfall as a Category 3 storm (I believe it was a Cat 1 or low end Cat 2). After that, I actually thought the storm was rather impressive – it had a ton of moisture and was extremely slow-moving. To be honest, I'm surprised that the storm held together like it did given that it was a fairly weak hurricane upon landfall.

    August 30, 2011 at 2:28 pm | Report abuse |
    • Alex

      fyi...I'm referring to the initial landfall over NC.

      August 30, 2011 at 2:34 pm | Report abuse |
  9. Yourculo

    Calling BS on the excuse too. The impact with the Outer Banks supposed knocked the eye out of then how come you were predicting it coming onto land as a Cat 3? --Which it didn't. It came on as a Cat 1 so the landfall didn't reduce it's intensity.

    August 30, 2011 at 2:28 pm | Report abuse |
    • wewatts

      People forget that weather forecasting is not an exact science. So they were off on the strength of the storm, it was weaker then they expected. Would have been happier if they had under estimated it's strength? What would you have said then?

      August 30, 2011 at 2:38 pm | Report abuse |
    • seriously226

      And millions of people are STILL without power and there is mass flooding. So it wasn't a Cat 3. That doesn't negate the amount of damage that it has caused. Millions were still affected – imagine what would have happened if it HAD been a Cat 3.

      August 30, 2011 at 2:43 pm | Report abuse |
  10. Creaturz

    I predicted the intensity and the path, and have people that can attest to it, so if i can predict it, why can't you bozo's?

    August 30, 2011 at 2:28 pm | Report abuse |
    • Jim

      What were the repercussions if you were wrong? Oh, that's right, "none" - no pressure makes for much easier predictions. If NOAA is wrong, people can die. If you're wrong, you don't get to make a snarky post on CNN.

      August 30, 2011 at 2:33 pm | Report abuse |
    • Alex

      Taking guess in meteorology is futile. It's a hard science. The forecasters were correct in thinking that it could strengthen.

      August 30, 2011 at 2:36 pm | Report abuse |
    • kurtinco

      Hallelujah, Jim. Creaturz is the bozo.

      August 30, 2011 at 2:37 pm | Report abuse |
    • Joel

      Because we're all bozos on this bus. Duh.

      August 30, 2011 at 2:50 pm | Report abuse |
    • Sky

      Actually, I predicted it as well...but mostly because of what meteorologists have been telling us all our lives. The storm wasn't very strong when it started going up the Eastern seaboard. The water this time of year is already getting colder. There were weather patterns to the West that kept shearing off the storm. I think they hysterically overhyped it to get ratings; HOWEVER, I am glad they warned people about flooding so in the end it may have been the right call. I think few of us who regularly experience hurricanes thought the winds were the danger, but I'm amazed at how such a little amount of rain caused so much flooding. I am glad people took precautions and hope everyone recovers quickly.

      August 30, 2011 at 3:13 pm | Report abuse |
  11. Clay

    Shoulda listened to Gore

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

    Uhhhh, wait a minute, didn't I just watch a show the other day about how people from India let rats run all over their food and drinking water because they are sacred animals? I saw people eating food out of a bowl with rats in it.

    August 30, 2011 at 2:30 pm | Report abuse |
  13. Ziggy Pop

    II just checked the local weather. I knew 48hrs before the storm came thru that wind speeds would hover between 40-60 mile an hour. I knew to expect 2-4 inches of rain. After the storm, wind speeds gusted to 60, and we got 2.5 inches of rain.

    I think they did a pretty good job.

    August 30, 2011 at 2:34 pm | Report abuse |
    • NotYou

      Your mom must be so proud.

      August 30, 2011 at 2:42 pm | Report abuse |
  14. John

    I'd love to have those two in my nature preschool, but there's something really important missing here:

    who told them to go to the basement?

    August 30, 2011 at 2:34 pm | Report abuse |
  15. RichXX

    NY isn't the whole world, just cause it didn't devastate there, ask the folks in Vermont. It was a devastating storm.

    August 30, 2011 at 2:34 pm | Report abuse |
    • wewatts

      The people in NY think they are the center of the known universe! Sooner or later a major hurricane is going to smack them, then watch them cry!

      August 30, 2011 at 2:41 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