Chapter 9: Weather forecasting Acquisition of weather information Acquisition of weather information Weather forecasting tools Weather forecasting tools Weather forecasting methods Weather forecasting methods Weather forecasting using surface charts Weather forecasting using surface charts

Acquisition of weather information

World Meteorological Organization World Meteorological Organization National Centers for Environmental Prediction National Centers for Environmental Prediction Watches and warnings Watches and warnings The internet plays a crucial role in the global communication of weather information The internet plays a crucial role in the global communication of weather information

Weather forecasting tools

AWIPS AWIPS meteogram meteogram sounding sounding

Satellites and weather forecasting geostationary satellites geostationary satellites polar orbiting satellites polar orbiting satellites Geostationary Operational Environmental Satellite Geostationary Operational Environmental Satellite infrared images infrared images visible images visible images water vapor images water vapor images Visible satellite images don’t provide useful information at night Visible satellite images don’t provide useful information at night

Weather forecasting methods

The computer and weather forecasting: numerical weather prediction analysis analysis numerical weather prediction numerical weather prediction atmospheric models atmospheric models progs progs One of the world’s first computers was built for the specific purpose of performing weather forecasts One of the world’s first computers was built for the specific purpose of performing weather forecasts

Why NWS forecasts go awry and steps to improve them grid spacing grid spacing chaos chaos ensemble forecasting ensemble forecasting Chaos theory tells us that weather forecasts are highly sensitive to our ability to observe the weather. Since it is impossible to observe the weather at all places at all times, weather forecasts will never be perfect. Chaos theory tells us that weather forecasts are highly sensitive to our ability to observe the weather. Since it is impossible to observe the weather at all places at all times, weather forecasts will never be perfect.

Other forecasting methods persistence forecast persistence forecast trend forecast trend forecast analogue method analogue method statistical forecast statistical forecast probability forecast probability forecast climatological forecast climatological forecast

Types of forecasts very short range forecast very short range forecast short range forecast short range forecast long range forecast long range forecast long-range forecasts are less specific than short range forecasts long-range forecasts are less specific than short range forecasts

Accuracy and skill in forecasting persistence persistence climatology climatology Both persistence and climatology are surprisingly accurate forecasting methods Both persistence and climatology are surprisingly accurate forecasting methods

Predicting the weather from local signs halo halo To see a halo: block out the sun with your hand and look at the cirrostratus clouds. Wear polarized sunglasses if possible. To see a halo: block out the sun with your hand and look at the cirrostratus clouds. Wear polarized sunglasses if possible.

Weather forecasting using surface charts

Determining the movement of weather systems forecasting rules of thumb forecasting rules of thumb using the surface chart using the surface chart

A forecast for six cities Augusta, Georgia Augusta, Georgia Washington, DC: rain or snow? Washington, DC: rain or snow? Chicago: major snowstorm Chicago: major snowstorm Memphis: mixed bag Memphis: mixed bag Dallas: cold wave Dallas: cold wave Denver: clear and cold Denver: clear and cold