Extreme Jet Stream Pattern Triggers Historic European Floods

[n2doc]

A historic multi-billion dollar flood disaster has killed at least eighteen people in Central Europe after record flooding unprecedented since the Middle Ages hit major rivers in Austria, the Czech Republic, Germany, Poland and Slovakia over the past two weeks. The Danube River in Passau, Germany hit the highest level since 1501, and the Saale River in Halle, Germany was the highest in its 400-year period of record. Numerous cities recorded their highest flood waters in more than a century, although in some locations the great flood of 2002 was higher. The Danube is expected to crest in Hungary's capital city of Budapest on June 10 at the highest flood level on record, 35 cm higher than the record set in 2006. The flooding was caused by torrential rains that fell on already wet soils. In a 2-day period from May 30 - June 1, portions of Austria received the amount of rain that normally falls in two-and-half months: 150 to 200 mm (5.9 to 7.9&quot , with isolated regions experiencing 250 mm (9.8&quot . This two-day rain event had a greater than 1-in-100 year recurrence interval, according to the Austrian Meteorological Agency, ZAMG. Prior to the late May rains, Austria had its seventh wettest spring in 150 years, which had resulted in the ground in the region becoming saturated, leading to greater runoff when the rains began.


Floods caused by a blocking high pressure system
The primary cause of the torrential rains over Central Europe during late May and early June was large loop in the jet stream that developed over Europe and got stuck in place. A "blocking high" set up over Northern Europe, forcing two low pressure systems, "Frederik" and "Günther", to avoid Northern Europe and instead track over Central Europe. The extreme kink in the jet stream ushered in a strong southerly flow of moisture-laden air from the Mediterranean Sea over Central Europe, which met up with colder air flowing from the north due to the stuck jet stream pattern, allowing "Frederik" and "Günther" to dump 1-in-100 year rains. The stuck jet stream pattern also caused record May heat in northern Finland and surrounding regions of Russia and Sweden, where temperatures averaged an astonishing 12°C (21°F) above average for a week at the end of May. All-time May heat records--as high as 87°F--were set at stations north of the Arctic Circle in Finland.

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http://www.wunderground.com/blog/JeffMasters/comment.html?entrynum=2432

[pscot]

1. This seems to be a typical effect

of a stalled jet.

[Arugula Latte]

2. Last year the UK got hit with the stalled jet steam.

Damn. I really feel for these people and animals.