Weather: Let's See How It's Done
Let's See How It's Done
You've gotten this far. You know the basics of what makes our weather click. You've learned how the weather is observed and measured. As far as weather forecasting is concerned, I'm convinced that the rest is really on-the-job training. After the basic principles have been mapped out, the remainder becomes a learning-by-doing process.
The best way for you to learn the skills of weather forecasting is by coming to work with me. By doing that you'll learn far more than reading more technical stuff. So let's take a look at a day in the life of Dr. Mel and see how I go about coming up with and delivering a forecast in front of a blank blue wall before 100,000 or so viewers.
Sunday Night?the Night Before the Forecast
Although I return to work on Monday morning, my preparation for the forecast begins with some careful thought about the weather the night before. Late Sunday, I begin to think about what has occurred during the weekend.
"I'm in prediction, not production."
The particular weekend in mid-October that I wrote this was pleasant, but changeable. On Saturday, the sky was crystal clear and deep blue. The visibility seemed to go on forever. I could look out from the Connecticut shore and clearly see Long Island's hills on the southern horizon, about 15 miles away. There was absolutely no haze, and the waves were hardly a foot. The weather vane pointed to the north, and because the tree limbs were just barely in motion, I knew that the wind speed was under 10 knots. All the ingredients of a dry, polar air mass were present. The temperature just reached 60 degrees that afternoon, about three degrees below normal. The deep blue sky and excellent visibility were dead ringers for a continental polar air mass. Also the wind was light, indicating a center of high pressure was nearby. Because of that system's clockwise circulation, a north wind would indicate that the high-pressure center was still to the west, but again, the light winds suggested that the center wasn't very far?250 miles or less.
Braving the Elements
Did you ever wonder how weathercasters stand in front of a blank wall and point to weather maps? The innovation they use is called chromakey, where the computer weather graphics are electronically merged with the blank wall. The weather anchor knows where to point on the wall by looking into television monitors to see the on-air image. I know from experience never to wear a shirt the same color as the blue chromakey wall at Channel 8?that blue shirt would come out blank on television, and instead of my shirt, you would see the computer graphic.
"Here, in this little Bay,
Full of tumultuous life
and great repose,
Where, twice a day,
The purposeless, glad ocean
comes and goes,
Under high cliffs, and far
from the huge town,
I sit me down."
On Sunday there were some definite changes. Skies became partly cloudy with clouds of the high and middle type. Cirrostratus, altostratus, and altocumulus clouds were in view. At the same time, the wind shifted to the south, and it became gusty. I could hear the waves breaking on the shore as far as 120 yards. The waves were building to about three feet. No longer was the visibility crisp and clear. A summer-like haze covered the sky. As the day progressed, the visibility dropped to five miles or less, and I could see no more than a third of the way across Long Island Sound. A major change in air masses had occurred. Instead of continental polar air, a tropical air mass seemed to have moved in. Later that afternoon, the temperature reached the 70s, about 10 degrees above normal. The barometer was falling steadily, indicating that the bright high-pressure system of the previous day was definitely moving away to the east.
The clouds increased later in the afternoon, and it seemed that more changes were on the way, but I had no way of knowing without looking at a bigger picture, beyond my own horizon. I turned on the television and the radio. There was no mention of rain for Monday, but there was a major story about heavy rains moving into Texas. The floods were extensive and took the lives of more than a dozen people. Something very dynamic was going on, and I remembered from the previous week that there were some signs of a major push of colder weather for the coming week. I thought for sure that those rains were on the leading edge of that polar air. A pretty strong cold front seemed to be out there, but I would learn more when I got to work Monday morning.
But before we go to early Monday, isn't it amazing what you can learn about the weather, just by looking and observing? With the slightest effort, you can tell what type of air mass is present and understand the factors contributing to the sky's appearance, the character of distant objects, even the nature of sounds, such as the breaking of waves. The more you look at the weather, the more you really see, and the more you really understand.
Early Monday Morning?Getting in to Work
The forecast you hear or watch in the morning has been hours in the making. I usually get up around 2:30 A.M., but on this particular Monday, I woke a bit earlier to the sound of rain. My first reaction was, "What's that about?" Nobody had called for pouring rain that morning, but I guess that southerly flow of moist air, and the approaching front meant business. On my way to work, the combination of falling leaves, and the rain made for some slick and slippery going. I made a mental note to mention that to viewers when I got on the air. But as I was traveling the seven miles to the studio, the rain stopped, and when I went out of the car, I looked up and saw some stars poking through the cloud cover. I thought, "That is a fast-moving front! Is that all there is?" Although the rain came down heavily, it couldn't have been more than a tenth of an inch.
Excerpted from The Complete Idiot's Guide to Weather 2002 by Mel Goldstein, Ph.D.. All rights reserved including the right of reproduction in whole or in part in any form. Used by arrangement with Alpha Books, a member of Penguin Group (USA) Inc.