Forecasting severe and extreme weather

Grading the dangerous weather

Hazard alerts contain information about the likelihood that the alert will occur, or that the storm is in progress. To increase the understanding of hazard warnings, we provide a description of the common consequences of weather.

What is an extreme weather?

Rarely, the weather will be a danger to life and property, if society is not prepared. If Meteorological Institute sends out an alert about dangerous weather ahead, the measures to reduce the damage can be initiated.

Notification of "extreme weather" compiled by a separate contingency plan. Snowstorms that may cause such a notice is:

• Strong wind
• Heavy rains
• Storm tide and waves
• Combination of weather elements above that individually do not meet warning criteria

Superior criterion for sending out notification of severe weather conditions is that it is likely that the weather will cause extensive damage or danger to life and property in a significant area of land (county / region).

Naming of extreme weathers

When Meteorological Institute sends alerts about an extreme weather, the extreme weather gets a name. The purpose of naming is to facilitate communication between authorities, the public, media and meteorologists, so that no misunderstandings will occur about which weather events are being discussed.

The name list is made in advance, and the names are being used continuously to identify the various extreme weather events. The list consists of male and female names, every second, in alphabetical order.

We avoid royal names, names associated with known profiles, names with the letters æ, ø, å and name starting with q, w, x and z. This is a practice that is recommended by the World Meteorology Organization.

See all named extreme weathers in Norway

History of the current notification system

New Year's Eve 1991 Norwegian Meteorological Institute notified wind of hurricane force in More og Romsdal the next day. Very few registered this weather forecast. Where the storm struck, the devastation was large. Both the public and authorities were unprepared despite a correct forecast was issued. No preventive measures were taken and no emergency was initiated in order to quickly remedy the major damage to infrastructure and buildings. Fortunately, no lives were lost. The incident showed that good weather communicated through public broadcasting (radio and television) was not sufficient to get the community to react when dangerous weather is in store.

Following this New Year's Eve hurricane, we drew up a notification plan for extreme weather events. The plan was adopted in 1994 and has since proven to be a useful tool for governments when it comes to limiting damage and saving lives.

Access to the danger alerts

• All valid danger alerts are available at yr.no
• Public users have access to halo.met.no
• Machine Interface for danger alerts are available from http://alerting.worldweather.org/

This also applies to danger alerts on lower level than extreme weather and other weather phenomenas:

• Difficult driving conditions
• Icing on vessels
• Forest fire hazard
• polar lows
• Kuling- and storm warnings for the coast and the fishing banks

Who is notified?

• NVE v / flood warning service
• JRCC south
• JRCC north
• County of affected areas
• Governor when touched
• Justice - and Police
• Police authority in the area - in case of evacuation
• Municipal agencies in the area - to ensure values
• Agencies that have national responsibility for communication (road, rail) and power supply
• Media