Meteorologisk institutt met.no LOKE – an extreme precipitation event in Western Norway, November 14th 2005 Anne Haaland Simonsen Met.no.

Meteorologisk institutt met.no

LOKE – an extreme precipitation event in Western

Norway,November 14th 2005

Anne Haaland SimonsenMet.no

Meteorologisk institutt met.no

What happened?

• An extreme weather event in Western Norway

• Period of much precipitation, 602 mm in 30 days (normally 259 mm)

• Observed 223 mm in 24 hours SW of Folgefonna glacier (Norwegian record is 229,6 mm in same area)

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Synoptic situation S aturday November 12th at 12 utc.

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Sunday November 13 th 2005 at 12 utc.

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Monday November 1 4 th 2005 at 00 utc

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Monday November 14th 2005 at 12 utc.

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Monday November 14 th at 18 utc

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BERGEN

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Problems caused by LOKE

• Closed roads• Costs due to damages on the roads

were approximately 4 mill. euros• One person lost his life in a landslide• The railway between Oslo and Bergen

were closed for several days• A 5 to 200 years flood in the rivers. The water level in a river between Bergen and

Voss rose to what was probably a 500 year level.

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How about the models?

• The prognoses showed 100 to 250mm in 24 hours, EC varied between 100-200 mm 4-7 days ahead.

• The highest amounts of precipitation varied from each model run, with the greatest intensity late Monday morning

• HIRLAM 5km from Sunday 00 utc showed 235 mm on 24 hours over southern parts of Folgefonna

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The 24 hours precipitation in the model is from 00utc monday to 00utc tuesday, it was in this period the models had the largest amounts of precipitation. Observed precipitation (18 -18) is plotte d for Før de (99), Takle (199), Lærdal (96) , Bergen (135) . and (06 -06) for Opstveit (223), Vats (117) and Sauda (107) mm.

88

223

107

199

117

96

135 150 mm

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100 mm

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130 mm

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235 mm

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Extreme Forecast Index (EFI) from ECMWF Saturday 12 November 2005 at 06UTC. Valid Monday 14 November 06UTC to Tuesday 15 November 06UTC

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Conlusion

• The prognoses were relatively good in this situation

• Made it possible to be out early with an extreme weather warning

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Sunday November 13 th 2005 at 12 utc.

In what kind of situations could we expect such large amounts of precipitation?• Position of high pressure

– Normally around 50 degrees north- With an east–west orientation– Warm, humid air is transported

north because of the high and then eastwards with the low activity on the north side of the high pressure

• Time scale of development– If the devolpment is too rapid, the

cold front is passing to fast and the most intensive precipitation is of a short duration

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Any questions?

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Extreme warning in Norway

• When there’s a risk that the weather will cause a danger for lifes and values.

• Strong wind, heavy precipitation, extreme risk of avalanche, extreme flooding

• Also dependent on the area• An extreme weather warning is sent out during the

72 hours before the event. • When there is less than 48 hours until the event, the

warnings are updated every six hour. During the event new warnings are sent out every 3-6 hours.

• The warnings are sent to Ministry of Justice, regional commissioner, the police, local authority, media.