Meteorology Chapter 9: Weather Forecasting

watch

A storm watch indicates that a storm poses a threat to an area (often within several days) and residents of the watch area should be prepared.

warning

A storm warning given when it is likely that a storm will strike an area within 24 hours.

AWIPS

Acronym for Advanced Weather Interactive Processing System. New computerized system that integrates and processes data received at a weather forecasting office from NEXRAD, ASOS, and analysis and guidance products prepared by NMC

meteogram

A chart that shows how one or more weather variables have changed at a station over a given period of time or how the variables are likely to change with time

soundings

An upper-air observation, such as a radiosonde observation. A vertical profile of an atmospheric variable such as temperature or winds.

analysis

The drawing and interpretation of the patterns of various weather elements on a surface or upper-air chart

numerical weather prediction (NWP)

Forecasting the weather based upon the solutions of mathematical equations by high-speed computers.

atmospheric models

Simulation of the atmosphere's behavior by mathematical equations or by physical models.

prognostic chart (prog)

A chart showing expected or forecasted conditions, such as pressure patterns, frontal positions, contour height patterns, and so on.

chaos

Th e property describing a system that exhibits erratic behavior in that very small changes in the initial state of the system rapidly lead to large and apparently unpredictable changes sometime in the future.

ensemble forecasting

a forecasting technique that entails running several forecast models each beginning with slightly diff erent weather information. Th e forecaster's level of confidence is based on how well the models agree (or disagree) at the end of some specified time.

persistence forecast

A forecast that the future weather condition will be the same as the present condition

steady-state (trend forecasting)

A weather prediction based on the past movement of surface weather systems. It assumes that the systems will move in the same direction and at approximately the same speed as they have been moving.

analogue method

forecast made by comparison of past large-scale synoptic weather patterns that resemble a given (usually current) situation in its essential characteristics.

statistical forecasts

A forecast based on a mathematical/ statistical examination of data that represents the past observed behavior of the forecasted weather element

probability forecast

A forecast of the probability of occurrence of one or more of a mutually exclusive set of weather conditions.

weather types

Certain weather patterns categorized into similar groups. Used as an aid in weather prediction.

climatological forecast

A weather forecast, usually a month or more in the future, which is based on the climate of a region rather than upon current weather conditions.

nowcast forecast

Short-term weather forecasts varying from minutes up to a few hours.

short-range forecasts

Generally used to describe a weather forecast that extends from about 6 hours to a few days into the future.

medium-range forecasts

Generally used to describe a weather forecast that extends from about 3 to 8.5 days into the future

long-range forecasts

Generally used to describe a weather forecast that extends beyond about 8.5 days into the future