|Met Office criteria||Possible effects|
|Severe gales||Repeated gusts of 70 mph or more over inland areas.||
|Storms||Repeated gusts of 80 mph or more over inland areas.||
Where wind is forecast above 90 mph the following may occur.
|Heavy snow||Snow falling at a rate of 2 cm/hour or more expected for at least two hours.||
|Very heavy snow||Snow falling at a rate of 2 cm/hour or more expected for at least two hours, accumulating to 15 cm or more.||
|Blizzard||Moderate or heavy snow accompanied by winds of 30 mph or more, with visibility reduced to 200 m or less; or drifting snow giving rise to similar conditions.||
|Severe blizzard||Heavy Snow accompanied by winds of 30 mph or more, reducing visibility to near zero.||
|Heavy rain||Rain expected to continue for at least two hours and to give at least 15 mm within a three hour period or, following previous heavy rain events, 25 mm/day.||
|Warning may be triggered by thunderstorms (warnings will state this if expected).||
|Fog||Visibility below 50 metres (restricted to heights where major roads occur).||
|Widespread icy roads, glazed frost, freezing rain||
When rain falls onto surfaces with temperatures at or below zero; or condensation occurs on surfaces at or below zero; or already wet surfaces fall to or below zero. The ice is usually clear and difficult to distinguish from a wet surface. It usually forms in sheets.
Warnings are issued when any depth of ice is expected over a widespread area.
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Orkney & Shetland
Highlands & Eilean Siar
Central, Tayside & Fife
SW Scotland, Lothian Borders
North West England
North East England
Yorkshire & Humber
East of England
South West England
London & South East England