Understanding Weather Forecasting

• Weather forecasting uses tools, observational data, science, and technology to predict weather conditions for a specific location hours, days, and months in advance.
• Before computer models, weather forecasting relied on observation, with the first computer-generated forecast in 1955.
• Weather forecasting is essential for both daily planning and long-term preparation.
• Forecasting involves continuously recording temperature, pressure, precipitation, wind speed, and cloud cover, and disseminating this information to the public.
• Current condition reports are used to predict future weather patterns.
• Accurate hazardous weather forecasts are crucial for saving lives, property, and crops.

The Weather Forecast

• Weather refers to the condition of the atmosphere at a specific time and place, including temperature, pressure, wind speed, and precipitation.
• A weather report describes current weather conditions.
• Weather forecasting aims to predict weather conditions from hours to weeks in advance.

Weather Forecasting Tools

• Meteorologists use various tools to measure and gather weather data.
• Outdoor thermometers measure air temperature.
• Barometers measure air pressure.
• Anemometers measure wind speed and direction.
• Hygrometers measure humidity.
• Radar detects objects in the air, primarily precipitation, by emitting microwave pulses and analyzing the returned waves.
• Radiosondes are balloon-borne instruments that measure and transmit pressure, temperature, and humidity back to a ground station, especially during severe weather.
• Data from these instruments are fed into computer models to generate weather forecasts.

Barometers

• Barometers measure atmospheric pressure, which is the weight of air above a given level.
• Air pressure and air temperature are related.
• Warm air is typically associated with higher pressure, while cold air is associated with lower pressure.
• Horizontal pressure differences caused by temperature variations result in air movement from high to low pressure areas.
• This movement of seeking balance is the essence of weather.

Radar

• Radar stands for Radio Detection and Ranging.
• Radar emits short microwave pulses that bounce back when they hit a target, such as rain or clouds.
• The returning wave is amplified and displayed, with the brightness indicating the amount of rain.
• Radar detects the location and intensity of precipitation.
• Red and purple colors on radar images indicate strong returns and intense precipitation.
• Radar can also detect the rotation associated with tornadoes.

Thermometers

• Thermometers measure air temperature.
• Liquid-in-glass thermometers, using mercury or red-dyed alcohol, are commonly used to measure surface air temperature.
• As air temperature increases, the liquid expands and rises in the tube.
• Temperature influences the state of water on Earth.
• Water freezes below 32°F (0°C) and is liquid above that temperature.
• Water evaporates or boils at 212°F (100°C).
• Water vapor holds more heat.
• The coldest recorded temperature was -128.6°F (-89.2°C) at the Soviet Vostok Station in Antarctica in July 1983.
• The warmest recorded surface temperature was 134.1°F (56.7°C) in Death Valley, California in 1913.

Computer Models

• Meteorologists use computer models for short and long-range weather forecasts.
• Computer models analyze incoming weather data to interpret weather patterns through numerical weather prediction (NWP).
• NWP models use mathematical equations with variables like temperature, pressure, and moisture to calculate changes over time.
• These equations are typically run for 12, 24, 36, and 48-hour forecasts.
• Computer models enable quicker and more efficient calculations than manual methods.
• Meteorologists combine computer model data with surface analysis to create weather forecasts.

Types of Weather Forecasting

• Weather forecasts inform everyday decisions, such as clothing choices.
• Probability forecasts use climatological data to assess the likelihood of specific weather events.
• Forecasting in the mid-latitudes is complex due to significant temperature variations.
• Common weather forecast classifications include:
  • Short-range forecasts: 12 to 48 hours in advance
  • Medium-range forecasts (MRF): 3 to 7 days (132 hours) into the future
  • Long-range forecasts: Based on probability for temperature and precipitation trends (below, at, or above normal) over 8-14 days, monthly, or seasonally.
  • Hazardous weather forecasts: Statements from the NOAA/NWS Storm Prediction Center (SPC) for potential severe weather within a seven-day window.

Examples of Hazardous Weather Forecasting

• Severe weather is dangerous.
• The NOAA and NWS created the Storm Prediction Center (SPC).
• The SPC's mission is to provide timely and accurate information about tornadoes, severe thunderstorms, lightning, wildfires, and winter weather to protect lives and property in the United States.
• Meteorologists continuously monitor forecasts and weather data for potential severe weather conditions.
• When conditions favor severe weather, a watch is issued for the affected area, and local weather stations, news outlets, EMS personnel, and trained spotters are notified.
• A warning indicates that severe weather is imminent or occurring, based on spotter reports or radar detection.
• Early detection through these forecasts allows people to prepare and seek safe locations.

Explore the tools, data, science, and technology used in weather forecasting to predict conditions. Learn about the evolution from observation-based methods to computer-generated forecasts. Discover how forecasting saves lives and protects property.