Meteorologist Forecasting Terms
Differences Explained Between Scattered Showers and Rain at Times
Forecasting Terminology
Using concise, standard terms for weather phenomena and events helps meteorologists prepare weather forecasts for viewers. Some of the most common terms heard during weather forecasts are used to explain the duration, distribution and intensity of precipitation and clouds.
Duration of Precipitation
- Brief - short, sudden showers or periods of rain
- Intermittent - on and off intervals, not continuous
- Occasional - irregular, infrequent intervals of precipitation
- Frequent - persistent short intervals, happening regularly and often
- Periods of precipitation - rain or snow falling most of the time with breaks
Distribution of Precipitation, as in showers
- Isolated - showers separated during a given period of time
- Few - indicated in time, not over an area
- Local - restricted to a smaller area
- Patchy - irregularly occurring in an area
- Scattered - not widespread but of greater occurrence than isolated showers
Precipitation Intensity
- Light - each drop or small flake of precipitation can be easily seen, puddles form slowly, some water flow in gutters
- Moderate - water puddles quickly, roads and other surfaces collect water, rain streams down windows
- Heavy - numerous flakes or sheets of rain, large puddles form, flooding can occur, visibility reduced
Cloud Cover
- Clear or sunny - free of clouds or less than one tenth cloudy
- Partly cloudy or partly sunny - three tenths to six tenths of the sky is clouded
- Mostly cloudy - the sky is predominantly clouded or seven tenths to eight tenths of the sky has clouds
- Cloudy or overcast - the sky is covered with clouds from nine tenths to a hundred percent cloud covered
Showers vs. Rain: A Difference of Duration and Intensity
Meteorologists tend to confuse viewers with weather terms for forecasting. Predicting scattered showers or periods of rain for the next day's forecast can be indistinguishable for some weather watchers. Showers are made up of rain yet duration and intensity differ.
The main difference between rain and showers is that rain is more widespread than showers. Rain at times or occasional rain will affect more of a larger area than frequent showers or scattered showers. Showers do not usually affect all areas with precipitation at the same time like rain. Showers have a shorter duration than rain. Showers begin and end more suddenly than rain. They can be short-lived and separated by blue sky or sun. Showers can be more intense, still covering a smaller area, with hail and heavy rain. Rain tends to be more uniformly steady and moderate or light in intensity.
- Rain - forms from stratus clouds, more widespread, steady, less intense
- Showers - forms from cumulus clouds, more isolated, short-lived, affects a smaller area, sometimes more intense
Another difference between rain and showers is the fact that they are produced by different cloud types. Showers are produced by cumulus clouds or convection clouds, clouds that rise and sink within the same cloud. Cumulus clouds are more isolated. Rain is produced by stratus type clouds, or layered clouds. These clouds are like a blanket, covering most of the sky, or a larger area than cumulus clouds.
Partly Cloudy vs. Partly Sunny
Yet another confusing set of weather terms are partly sunny and partly cloudy. According to the National Oceanic and Atmospheric Administration there is no official difference between the two terms. It is important for meteorologists forecasting the weather to emphasize one or the other, to help clarify the meaning of the term used.
References:
Austrailian Government Bureau of Meteorology
Clouds at Sunset
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