The News Herald (Willoughby, OH)
Forecasting relies on savvy and technology
Experience weighs heavily in prediction mix
While technology may play a key role in helping to predict the weather, human intuition and experience tends to be the deciding factor when creating a weather forecast.
Meteorologists such as Nick
EDITOR’S NOTE: This is the second of a two-part series looking at how science, technology and human knowledge and intuition combine to forecast weather in Northeast Ohio.
Greenawalt, who works for the National Weather Service’s Cleveland Forecast Office, runs various
weather forecasting models on computers to find the best one for predicting a five-to-seven-day forecast for Northeast Ohio. The models are just guidance, though, and it’s up to the meteorologist to decide which one to trust.
Greenawalt said the models, which essentially are just a lot of different computer equations, take in observations from not only the country but around the world on a daily or even hourly basis.
Some of the factors that go into these equations include the weather that’s happening around the world, the temperature, the dew point and the wind speed. Meteorologists will look at satellite data, and some of the models will even look at current radar data.
If the model output matches up to current conditions and to what happens the following hour, they extend it out five to seven days, with some models predicting up to 10 days.
The process doesn’t solely rely on the models. Meteorologists have to rely on their intuition and knowledge
of the weather and environment.
When Greenawalt is trying to come up with a weather forecast he will look at the conditions the model thinks are happening versus what is actually happening at that time on radar.
“If the current conditions don’t seem to be modeled very well then I’m not going to have as much confidence in it 12 hours from now,” he said. “The first step in the forecast process is just to identify what is happening out there right now.”
The National Weather Service generally forecasts out to about seven days
with their main focus being in the first couple of days. That is because there is more data and more models available in that time frame and it’s also easier to look at the overall weather pattern, Greenawalt said.
They are able to use the guidance from the models to help them paint a picture of what they expect to the weather to be like for up 3672 hours. Beyond that, models tend to change every time they are run once you get out to four to five days.
“That is why there is a lot of uncertainty when you hear a five-day forecast, “Greenawalt said. “It’s because we have a few different
models that we look at. We compare them and we know which models do well in which patterns and which patterns tend to under forecast precipitation or over forecast the temperatures and things like that. “So we use our forecaster experience and our pattern recognition to see what the models are doing and adjust it to try to put out a consistent and accurate forecast.”
The National Weather Service Cleveland Forecast Office is staffed round the clock, every day of the year with two meteorologists. On a routine basis, it issues forecasts for marine, fire,
aviation-specific, and wind and wave.
The aviation forecasts go out every 24 hours but is updated every three to six hours.
“The aviation specific forecast is one of the most important things that we do. We have actually seven different airports that we do the specific forecast for in our area,” Greenawalt said. “That’s something that impacts a lot of people and a lot of people don’t realize the role we play in predicting that weather in those conditions so they can get as many planes in and out as possible and as safely as possible as well.”