April Weather: All the Above
April Weather: All of the Above
These days, your typical five-day weather forecast is about as much help as consulting your daily horoscope, which is to say none whatsoever.
Take this week: Rain. Partly cloudy. Chance rain. Mostly cloudy. Rain likely. Sun breaks. Showers.... Each daily forecast has that little picture of a shower and a cloud with the sun peaking out from behind. Translation: Expect any or all the above. Each should be followed by a question mark.
For serious sailors, this works fine. Go ahead and raise sails; if you don’t have some wind and sun, just wait a few minutes.
But the rest of us are left to wonder why we pay all those smart people down in Seattle to offer the same forecast, day after variable day.
Mike McFarland understands. He’s one of those smart people who works at the National Weather Service in the city. He lives in the infamous Snohomish County “convergence zone,” and frequently spends time at his parents’ home in Cape George, gazing across Discovery Bay and trying to unravel the meteorological mysteries in this fickle corner of the atmosphere.
And these days, he confesses it’s mostly guesswork. December forecasts are pretty reliable – think wind and rain, he says. Summer forecasting is even easier.
But April? “Not so good,” he says, a little apologetically. “”We do pretty well forecasting major floods, and a fair job of gale warnings. But everything else is, well, not very skillful.”
McFarland was the guest speaker recently at the Port Townsend Yacht Club, where more than 100 of us mariner types showed up for an inside look at how the weather guys do what they do.
The challenge around here, he explains, is too much geography – mountains and bays and a very large ocean, he says. If he were doing the weather in, say, Kansas City, life would be much simpler.
Look for yourself. Go to www.weather.gov, the National Weather Service site; or www.atmos.washington.edu, the University of Washington’s. You’ll find data from weather satellites, from weather balloons and ocean buoys, computer models and radar data. Some of it is useful, some isn’t. Radar, for example, is almost useless, McFarland says – too many mountains in the way.
“Everything we use is now on the Internet,” he says. The TV guys use the same data as he does, except it’s prepackaged with those whizbang graphics.
In the Northwest, the most useful tool is that familiar weather map, with its contoured lines, or “gradients,” showing relative changes in atmospheric pressure. When those gradients are widely separated across the map, things stay stable; when they’re close together, watch out. And in April, they’re usually bunched up “like spagetti,” he says.
Then there’s the jet stream across the Pacific. “What matters is the strength of jet stream, where it curves and how sharply,” he says. “A slight change may divert a storm we thought was headed for Forks, and push it up to the Queen Charlottes.”
Those are the times that NOAA predicts 10-knot northerlies in Admiralty Inlet, and they turn out to be 15-knot southerlies, or vice versa.
It’s all so variable and inconclusive that, “after any official forecast, you can look out your window and improve on it,” McFarland says.
Take fog, for example, which can’t be predicted or even detected by technology. “Our fog forecasts are terrible.”
That’s why the weather guys supplement all their data with live information from volunteer spotters, amateurs who read their own gauges, then look out their windows and call the Weather Service to report what they’re seeing – like fog.
The service also makes good use of the state ferries, each of which carries automated weather equipment. “At first, the Port Townsend-Keystone run was giving us terrible data,” he says. “Turns out the equipment wasn’t allowing for the speed of the boat.”
So it all comes down to data, computer models and experience, he says. Human beings can improve somewhat on the computer models – but not much.
Here in Port Townsend, there is some consolation in the famous rain shadow, he says. Less rain, more sun. “You picked the right place to live.”
