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Thoughts on the Atlanta Snow Debacle

January 30, 2014 by tornado Leave a Comment

      Photo courtesy Georgia D.o.T.

A horrendous winter-weather debacle unfolded in Atlanta and a few other Southeastern cities two nights ago, far, far out of proportion to the puny total of precipitation that fell. Less then three inches of snow basically paralyzed a metro area. As I got wind of this, and as a professional meteorologist with an unnamed entity that I’m not representing here, I couldn’t help but think, “Why”?

Notice the question isn’t, “Who is to blame?”, but is the more fair and balanced, “Why?” That’s a deliberate distinction. Asking questions, trying to get to the bottom of things, and finding holes in the Integrated Warning System that lead to disasters, is not the same as blaming. If you can’t understand the difference, stop reading right now. The rest will make no sense.

Being an atmospheric scientist and forecaster by trade, my first inclination was to look at the available public- and private-sector predictions for the event. My impression was they, while not perfect, they generally were very good–including and especially the forecasts from NWS Peachtree City. Contrary to the impulsive, borderline slanderous scapegoating by the Georgia governor and city officials, with no understanding or justification of how forecasting uncertainty works, I came away with the impression that an extremely difficult forecast was performed fairly well. This story on the backlash from some private-sector meteorologists illustrates that well.

Were all the forecasts from all sources good? Probably not. James Spann, Birmingham TV meteorologist for whom I have a great deal of respect, perhaps was too hard on himself when he said, “Days like yesterday, unfortunately, are part of my job. There have been bad forecasts in the past, and there will be bad ones in the future. Football coaches don’t win every game, and we don’t get every forecast right. But, when you lose, you do deep study into what went wrong, and work to be sure it doesn’t happen again.” The undercurrent there, however, is that forecasting cannot be totally right; and to expect perfection is just plain stupid. Please understand a key part of what James stated: There will be bad ones in the future. His ethic of learning and improvement is exactly the right attitude to take–not only in weather forecasting, but in preparedness for bad weather (more on that below).

Meanwhile this quote from Nathan Deal illustrates the problem that politics causes: “If we closed the city of Atlanta and our interstate system based on maybes, then we would not be a very productive government or a city. We can’t do it based on the maybes.” News flash, Nathan: forecasting necessarily involves maybes. It’s called uncertainty, and is unavoidable in forecasting. Get used to it, and plan accordingly, instead of complaining about forecasters failing to meet impossible standards of perfection.

While those ignorant blowhard politicians thunder their hollow indignation across the TV screen and throw the local NWS under the bus, I’d like to put Peachtree City up for a medal. Although not a forecaster by trade, Marshall Shepherd offered a hugely appreciated and very well-reasoned summary of the problem, including a strong message of thanks to the forecasters. So…thank you, Marshall. You beat me to a lot of the same points, and saved this BLOG entry from being even longer than it already is.

To that, there’s little I can add regarding the forecasting. A better predictive performance with such a hard and uncommon (for them) type of event as a sub-mesoscale northern edge of a snow band–especially more than a few hours out (when a winter storm warning was in effect)–would be demanding the unreasonable. Alas, because the response to the event and the resulting impact thereof each were so ghastly (which is out of control of the meteorologists), such an award isn’t likely to happen. That’s a shame.

Response and preparedness–which are two different but interlocking facets of the Integrated Warning System–absolutely do matter! The readiness in Atlanta, both governmentally and on individual levels multiplied by hundreds of thousands, was nothing short of wretched. Even in Dallas, San Antonio and Houston–cities of roughly similar metro populations as ATL that are farther south in latitude–hasn’t experienced an ordeal like that in their winter-weather events. Could it be that even in those places, just enough folks know to cancel plans in advance when winter weather is forecast?

Vehicular traffic is horrid in Atlanta on many a fair-weather day, and just one or two well-misplaced wrecks can render the situation FUBAR. Have you looked at a road map of that place? There are hardly any gridded, straightforward alternative routes to the freeway system, which itself looks like twisted noodles. Throw hundreds of thousands of vehicles onto that nonsensically chaotic spaghetti diagram at once, and into conditions for which few of their drivers are individually experienced or prepared, with essentially no pre-treatment or treatment of roads thanks to lack of suitable equipment, material and foresight at the civic level, and voila! You get what they got. In such gridlock, with the cars that can spin their wheels going nowhere in the process, the situation goes from FUBAR for a couple of hours to unprecedented and dangerous stasis. This was preventable.

Individuals: There is individual responsibility in this! Be aware of the forecast–the very latest forecast, since they can and do and should change as the event gets closer. Pay heed. If you’re inexperienced at driving on ice and snow, then don’t drive in ice and snow. Stay at home. Leave the roads clear for those who really need to be out there. If already at work, stay there awhile and let things clear up–it’s a warm place and beats sitting in traffic the same amount of time or longer with a hundred thousand other lemmings, burning gobs of fuel, stressing over being stuck, risking hypothermia should the need to evacuate the vehicle arise, and potentially being hit by idiots sliding into you.

State and local governments: All disasters are local. This means it’s up to you to be ready–not 1-3 days before, but months before. It’s not up to forecasters to do the impossible and tell you exact snow depths tomorrow down to the block and lot. You have to make decisions based on uncertainty! Deal with it…that’s your job. Maybe it’s not “cost-effective” for a big southern city that does get pretty cold sometimes to have access to lots of sand and salt trucks, and the sand and salt to go therein, and a strategic contingency plan with short-fused, priority-driven disbursement of the vehicles and material. Fine–don’t complain, then, when the cost/benefit ratio you so carefully weighed turns out to be wrong and comes back to bite you hard. Learn from this and quit trying to play childish blame games. Cooperate across city and county and school-district borders instead of myopically operating as insular little fiefdoms; the North-Central Texas Council of Governments (“230 member governments including 16 counties, numerous cities, school districts, and special districts”) is a great template to follow! Finally, emergency management exists for a reason, and this qualifies as an emergency. Make use of that expertise already located right under your noses.

Politicians: Admit your mistakes, for once, in a very specific manner, with clearly stated plans for how you’re not going to repeat them. Quit trying to blame those least deserving of it (and as public servants, least in a position to defend themselves). The Ray Nagin school of blame-shifting should have been closed long ago.

Media: You are the mainline communicators between meteorology and the public. I have one “don’t” and a lot more “do’s” here. Don’t give mixed signals, multiple model forecasts, and other confusing messages. Do keep it clear and straightforward. Do express uncertainty, and use that to convey the “better safe than sorry” message. Do keep up with changes in the forecast, because uncertainty mostly tends to shrink as the event gets closer. Do everything possible to encourage caution, safety and preventative avoidance of the roadways in a winter-storm scenario.

Forecasters: You (we) did well, overall. Not perfectly, but under the circumstances, not bad either. We all can learn and improve from this event, as James alluded. Remember: there’s more to consistently reliable forecasting than just models. Some folks actually hand-analyze surface and upper-air charts, investigate satellite imagery, examine and modify real soundings, and perform other physically insightful diagnostics of the actual atmosphere before ever invoking the prognostic models. Thorough analysis is the difference between merely seeing and truly understanding. This is also part of Snellman’s “Forecast Funnel” approach and is time-tested. The day we let the models do our jobs for us is the day those jobs can be automated.

This event was a woeful concatenation of misfortunes: natural forecast uncertainty, unprepared and ignorant individuals times hundreds of thousands, communications failures, badly designed transportation options, terribly ill-prepared governmental entities, and the worst timing of a snow event with respect to a weekday commuting scenario. The bottom line: Winter weather is only as bad as your preparedness for it. Take heed, Atlanta, and do it better next time. Let’s all learn from this, lest it be repeated.

Filed Under: Weather AND Not Tagged With: analysis, Atlanta, Atlanta snow, Atlanta snowstorm, blame game, Cobb County, communication, emergency management, emergency preparedness, forecasting, Fulton County, Georgia, gridlock, ignorance, individual responsibility, media, models, Nathan Deal, politicians, politics, preparedness, snowplows, stupidity, traffic, transportation, winter storm, winter storms weather prediction, winter weather, winter weather prediction

Forecasting the Ensemble Outlier

February 9, 2011 by tornado 1 Comment

Several days back, I posted some thoughts about a pretty good short-range ensemble (SREF) spot forecast of a recent snow event in the Norman area. Now let’s look at even more recent ensemble forecasts that were absolutely wretched–so much so that even the most extremely low outlier in the latest of the two forecasts was overdone by a factor of nearly 2.5!

When is forecasting at or even beyond the outlier the best choice? When it’s the closest to correct! Granted, that’s easy to say in hindsight; but the cold truth is that the atmosphere does hold the answer key. Forecasts are judged in an objective sense by their closeness to the verifying quantity. In this case, it’s accumulated snowfall.

Below please witness two different SREF runs’ predictions for Norman snow, in the form of plume diagrams (explained in the previous link above). The answer key, in the form of the average snow depth measured at my house, is in magenta. [NOTE: The vertical scales are not exactly the same. Look at the numbers at left, in inches.]

Model initial hour 21Z Monday:

Model initial hour 15Z Tuesday:

The best spot forecast here clearly would have been for the greatest probabilities and/or snowfall ranges skewed strongly toward, or even beyond, the low end of the distribution. Following the cliff-leaping lemmings of ensemble consensus here would have been a miserable forecast failure. There probably are many more lessons here than my fading, sleep-deprived mind can muster, but I can offer two for now:

  1. The outlier sometimes is the best solution! Forecasters get paid to produce the best possible prediction; and sometimes that means forecasting way above or below the average or “consensus” model forecast. Clearly leaning heavy toward the low extreme would pay off here. I don’t pretend it’s easy; but since when did anyone promise that forecasting is supposed to be? For more discussion on this issue, see this 5-year old post on ensemble forecasting–specifically, scroll down to the “Consensus Forecasting vs. Extreme Event ‘Outliers'” section.
  2. Spot forecasting for something like forecasting a banded snow event, which can vary wildly based on subtleties that observations or models cannot resolve well, probably is a foolhardy endeavor. Parts of northeastern Oklahoma have had over 20 inches of snow from the same event! Norman stayed outside the southern fringes of a persistent, mostly W-E aligned snow belt that belted parts of northern Oklahoma, southern Kansas and northwestern Arkansas.

Filed Under: Weather Tagged With: ensemble forecasting, ensemble mean, ensemble outlier, plume diagram, snow, snow forecasting, spot forecast, SREF, winter weather, winter weather prediction

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