market for a weather emergency radio, check to see whether it has this special tone alarm feature.
A Warning is issued when potentially dangerous weather is possible within a matter of minutes and residents should seek shelter. A warning means no fooling around — it’s time to take some action.
A Severe Weather Statement often follows up on a warning, to cancel it or modify the area of concern. Also, this statement might alert residents to the presence of such hazards as funnel clouds that are not expected to touch the ground.
Water, water, everywhere …
A major weather-related killer in the United States is flooding — not the winds of a hurricane or a tornado — and the especially dangerous circumstance of high water has its own set of National Weather Service bulletins.
A flood is called a flash flood because it is sudden. It takes place within a few minutes or a few hours of heavy rainfall or some other event like a dam break or a river levee failure. Most flash flooding is caused by torrential rains from thunderstorms or the rains of hurricanes or tropical storms.
Every state in the United States has been hit by flooding of one kind or another. Rivers flood sometimes in the spring when runoff from heavy rains combines with water from melting snow, although floods can happen any time of year. Along coastlines, the winds of powerful storms can generate big waves and high tides and storm surges that cause coastal flooding. The streets of every city can fill with water of urban flooding when circumstances are just right — or just wrong!
The National Weather Service issues these special flood warnings:
A Flash Flood Watch or Flood Watch is issued when flooding is possible. Be alert to signs of flooding and be ready to evacuate to higher ground.
A Flash Flood Warning or Flood Warning means flooding has been reported or is imminent. It is time to act, and to act quickly, to save yourself.
An Urban and Small Stream Advisory alerts you to the fact that flooding is occurring on some small streams or streets and low-lying areas such as underpasses and storm drains.
A Flash Flood Statement or Flood Statement contains follow-up information about a flood event.
Flavors of Forecasts
Depending on where you live and what you do, the weather forecast you wake up to in the morning probably lets you know what basic conditions to expect of the day. Sometimes it delivers important information about your safety or comfort, and every day millions of people rely on it without giving it much thought.
In the newspaper, on the radio, on television, and on the Internet or smartphone app, the basic weather forecast is usually routine, simple, and to the point. It directs itself to the questions that most people want answers to as they start their day. How warm or how cold is it going to be? Will it rain or snow? Is a storm on the way? Will the wind blow? Before this day is over, will I need an umbrella or a light jacket or a heavy coat?
The National Weather Service and other agencies and private companies also prepare daily a number of specialized forecasts. They provide important weather information about the day, or the next few days, to a variety of special audiences around the country. Private forecasting companies supply specially tailored forecasts for hundreds of special users such as utility companies, construction companies, hotels, ski resorts, and motion picture studios.
Here are some of the more common special forecasts.
Agricultural forecasts
A farmer wants to know everything you want to know about tomorrow’s weather, but the farmer also has to keep an eye out for a few other special things. Much depends on the average seasonal conditions, or climate, of the region, and, of course, on the kinds of crops in the field.
All farmers are on the lookout for frost, because of the damage it causes to crops. In areas with large citrus orchards and vineyards, where freezing temperatures are rare, growers use large outdoor fans and heating devices to keep their trees and vines from freezing. These fans cause the coldest air, which is nearest the ground, to circulate with warmer air above it.
The U.S. Department of Agriculture and many private companies provide farmers with weather forecasts tailored especially to their local needs around the country.
Aviation forecasts
Forecasters provide specific nowcast guidance for Federal Aviation Administration air traffic controllers to use in advising pilots for flight planning and flight operations. (If you’re unfamiliar with nowcasts, see the section “Take what is happening now …” earlier in this chapter.)
Also, many of the automatic and manually operated weather stations are located near the touchdown zones of airport runways. The readings from their instruments are automatically broadcast to pilots. (See Chapter 16 for more on these and other tools of the trade.)
Using communication satellites, the National Weather Service now beams a new radio broadcast system called the World Area Forecast System to pilots of commercial airliners around the globe. This tool gives them the best information available about such things as upper-level winds and temperatures, which is crucial to aviators (and their passengers!).
Marine forecasts
No group is more dependent on weather conditions for their safety and well-being than mariners — professional sailors, recreational boaters, and commercial and sports fishermen.
Monitoring coastal and offshore conditions, the National Weather Service forecast offices in coastal areas around the United States and in the Great Lakes region issue a variety of specialized forecasts and warnings for professional mariners and recreational boaters.
Marine forecasts let boaters know what kinds of winds to expect, whether the sea will be calm, and, if not, the height and direction of rolling swells. Small craft warnings for strong winds or fog conditions and other hazard advisories are issued in areas along the seacoasts and the shores of large lakes.
River forecasts
National Weather Service forecasters work closely with hydrologists, who are water experts. A weather forecaster estimates how much rainfall is likely from a particular storm, and the hydrologist figures out how much that precipitation will cause certain rivers and streams to rise.
Forecasters also keep operators of federal and state dams informed as major storm systems approach large river systems. Sometimes a dam is good for saving
