John D. Cox - Weather For Dummies

A Watch , such as a tornado or severe thunderstorm watch, is issued when dangerous weather conditions like lightning, large hail, and damaging winds are possible for the next several hours. It’s time to be on your toes.

An Advisory , such as a winter weather advisory or wind advisory, is issued when conditions are not life-threatening but still worth keeping in mind. These are especially valuable to travelers in areas experiencing such hazards as snow or winds or fog. Maybe it’s time to slow down and think ahead.NOAA WEATHER RADIOTimely weather information is readily available to anyone with an FM or AM radio or television set, and most National Weather Service forecast offices maintain a website. But what happens when things go badly? If it’s emergency preparation you’re thinking of, a battery-powered NOAA Weather Radio belongs in a disaster supplies evacuation kit.This official weather emergency radio service is the only direct link the National Weather Service has to the public. It operates from about 500 transmitters in 50 states and U.S. territories on seven frequencies in the VHF band, ranging from 162.400 to 162.550 megahertz. These frequencies are outside the normal range of AM and FM broadcasts, although some manufacturers are including NOAA Weather Radio as a special feature on some receivers.Nearly every National Weather Service office operates at least one NOAA Weather Radio transmitter broadcasting weather information 24 hours a day. The average range of these transmitters is 40 miles.During severe weather, a tone alert can be activated to cause radios equipped with the alert feature to sound an audible alarm. If you’re in the 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.

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.

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.

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.

Another key indicator for many farmers is the combination of sunshine, heat, humidity, and wind conditions that let them know how much evaporation of moisture from their fields to expect. This evapotranspiration rate is closely watched by farmers who irrigate their fields.

The U.S. Department of Agriculture and many private companies provide farmers with weather forecasts tailored especially to their local needs around the country.

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 16for 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!).

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.