The Challenge of the Year

There are a few sayings in the field of weather forecasting that speak volumes with just a few words. "If you don't like the forecast just wait 5 minutes" or "The forecast is always right; Mother Nature doesn't always follow the script." A weathercaster I interact with online says "I'm into prediction, not production!"
We forecasters are a very lucky bunch. We have at our disposal a collective knowledge of the atmosphere that grows exponentially on a yearly basis. We have the science of probing and measuring the potential within a slice of sky down to an art form. Weather balloons, radar, aircraft, radiosondes, all costing millions of dollars and man hours are at work everyday so that we (and you) might know what's coming. Will it rain today? Snow? From which way will the wind blow? Every morning, I get to the station very early so that these questions can be answered....and if all goes well, the answers will be correct.
There are some meteorologists out there that feel the learned forecaster should be awarded a Bachelor of Arts opposed to the B.S. degree commonly won at our collegiate institutions. I agree. Forecasting is an art. You have to visualize the sky three dimensionally. Think of the atmosphere as a river or stream. After all, it helps to know the science of fluid dynamics in order to get a meteorololgy degree. Lets say your town is a medium sized stone at the bottom of a stream. There will be times when the water is warm and others when it will be cold. Sometimes the colder water will be on top, and times when it will be on the bottom. There will be times when the water "overstone" will be relatively swift, then slow over time. A 5 year old child can see that a river flows. Therefore there's an obvious horizontal motion in our river. What we may not see is a vertical flow, the result of temperature differences. The source of the cold water is often the cold atmosphere above, but cold water is more dense than the warmer stuff so it feels more at home at the bottom. These motions in a stream or river are at times a mirror image of our sky above Wichita Falls, or any other point on earth for that matter. Now I better get back to weather forecasting before I venture off into claiming the knowledge of an oceanographer; Which is not the case.

Despite all this collective scientific knowledge and the gadgetry to exploit it, how can someone throw a dart and get a forecast right while the "weatherman" gets it wrong? Well, in a nutshell, Mother Nature clearly has the upper hand. Even though we know a lot, especially the atmosphere's habits, we don't always know it's intentions. The operational models that greatly influence our forecasts are built on data from past occurrences. If a certain environment or condition exists at the time a weather balloon goes up, the forecast model will take the fresh collected data and match it to the last time the condition existed and then make a forecast based on the past occurrence. "Oh dear, I've gone crosseyed" to borrow a phrase from Austin Powers. It's a complex process indeed, but the data is priceless. Models work well most of the time. For example, big rain events are pretty easy. We can see those coming several days in advance. In fact, If there's one thing I'm pretty confident in, its forecasting rain. On the opposite side of the house is surface winds. It's virtually impossible to project a reliable wind forecast past 3 days. Forecast models are very poor at handling cold air masses that are less than 2,000 feet deep. There has been local evidence of that many times just in the past 5 weeks. Also models cant really "see" changes in our weather that happen in a span of time less than 5 hours. The key to knowing how to use forecast models is knowing when they are "out to lunch" and not projecting a proper forecast. Kind of a "garbage in, garbge out" scenario.

Here's how I look at an extended forecast. For example, at work, I end my weathercasts with the 6 day forecast. Its the most time consuming part of my morning preparation. Even though I treat each day of the 6 with care, realistically the odds of a precise forecast over more distant time are not in my, or anyone else's favor. In the real world, and in my honest opinion, each day loses a 10% degree of reliability. For example, for day one, tomorrow, chances are about 80% that forecast is correct, day 2 70%, day 3 60%, and so on. Leaving day 6 with only a 30% probability. Given the millions of changes and fluctuations in our atmosphere over a 6 day (144 hour) span, we're lucky that we can even suggest a temperature within 15 degrees.

Why do extended forecasts become less precise with time? Here's an example. Lets say a weather balloon is launched at 6:00am in San Francisco. Weather balloons report weather at what we call mandatory levels of the atmosphere. These are uniform points at which th balloon makes and sends an observation of temperature, pressure, humidity and wind direction and speed. Ok, this particular balloon observed winds of 65 miles per hour from the southwest at and altitude of 20,000 feet. That would suggest to the forecaster that there is a trough of low pressure out to the west. This alone does not a forecast make, but this observation along with readings from thousands of balloons launched every 12 hours lets the forecaster see how the atmosphere is flowing. Based on these observations we can, along with the operational models, project the state of the atmosphere for tomorrow and beyond. Ok, back to our San Francisco balloon. Based on the reading of 65 miles per hour (actually it would be knots) from the southwest at an altitude of 20,000 feet, the forecaster might say that 24 hours from now the winds speed and direction at the same altitude will be 75mph from the south-southwest, suggesting that our trough out west will become more well defined. When our forecaster receives the reading from the balloon the next morning he finds that the actual observation was 57mph out of the west-southwest, suggesting that our trough is becoming more vague. Result? The forecast has to be re-thought. This is an example of how very small changes over a short span of time can result in huge changes over a matter of days.

I've been forecasting the weather both part-time and full-time for about 6 years now. I would like to think I'm getting better and more confident in my abilities. There's still a lot I have to learn, or better yet, a lot I have to experience. 6 years down the road will I be twice as good? Doubtful, but my collection of experiences will be doubled. I'm pretty good at forecasting the big stuff, rain, cold blasts, severe weather, now I have to work on the small stuff in order to make my forecasts more valuable. For example, on those days when a cold front has pushed through and left us with a thin layer of morning clouds. Knowing whether or not those clouds will stick around in the afternoon or if they will break and allow sunshine to brighten our day is a challenge; a challenge I get a few times a month. There are several factors that go into that forecast, but with each attempt, each experience, I'm better equipped for the next challenge. In 2004 I became familiar with some new forecasting approaches, more specifically some computer software that allows me to better visualize the 3 dimensions of the atmosphere. Yes, its another tool to help my precision, but nothing equates to the experience of trial and error.

2005 has been a bear so far. There have been numerous cases of shallow cold air (not handled well by models) slipping into the Red River Valley and completely destroying the forecast. Those hurt!. When the actual high is 15 degrees colder than the high you projected only 10 hours earlier, well that could cause me to delay my trip to Wal-Mart for a few days. There was an instance just last week when the National Weather Service issued a Heavy Snow Warning for the area. I followed suite saying that accumulations of 4-6" were possible over the next 24 hours, and it didn't even snow! You know its bad when you start getting dirty looks from school kids! So, even with all this technology that surrounds me and the experience I've gained over time, becoming a better forecaster will be the challenge of the year. I take my forecasts very seriously. In fact, I get upset if a temperature projection is off the mark by more that 5 or 6 degrees. When clouds don't break in the afternoon, when I suggested they would, that really gets to me. So my forecasting precision actually has an emotional parallel.

Weather forecasters are a valuable lot. A knowledgeable bunch that, in effect, predict the future. I think its fair to say that the advancement in forecast precision over the last 20 years is immeasurable. Especially when it comes to the small stuff that makes the difference between clouds and sun in the afternoon. That being said, and after every scientific and technological advancement bears its fruit, one thing is perfectly clear. Mother Nature will keep us guessing.

JC