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Finalized Material from: Linus, Ivan

Discussed in the following Daily reports:

1. Impact

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Excerpt
During the week 29 June to 5 July a heatwave affected western Europe, and several July temperature records were beaten, among them the UK July record when Heathrow measured 36.7C on 1 July.

The heat wave spread across many parts of West and central Europe. A ridge from the South built up over western Europe, bringing hot tropical air from Africa. Several significant all-time records have been reported. This heat wave has affected Spain for the most of the week. On Monday, 29 July Madrid broke the record for June temperature measuring 39.7C. Few days later all-time July record also was broken with a temperature above 40C. On Tuesday, 30 June temperatures on southern Spain reached nearly 44C. Heat wave affected France as well. Several locations across France established all-time temperature records. On Wednesday, 1 July the temperature in Paris reached 39.7C, the second highest temperature in the city ever. On the previous day, 30 June SW France recorded temperatures of 42C.

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Our forecasting system was able to give the onset of this heat wave about 2 weeks in advance. The plots below also show the EFI for 2-metre maximum temperature for day 7, the longest lead time available. The EFI signal is exceptionally strong for this lead time picking up well the most affected areas. HRES also performed very well managing to provide the right magnitude of the highest temperatures pretty well in the medium range (on the plots below 4-day HRES is displayed).

The case is discussed in a Newsletter article: http://www.ecmwf.int/sites/default/files/elibrary/2015/14589-newsletter-no145-autumn-2015.pdf

http://www.bbc.co.uk/news/world-europe-33341325

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2. Description of the event

The plot below shows the evolution of EFI for 2-metre temperature for three cities (Madrid - blue, Vienna - black and Stockholm - light blue) from the last week of June up to mid August. The solid lines are based on 1-day forecasts and dashed on 6-day forecasts. For Madrid more or less the whole July was extremely warm, while Vienna had 3 separate periods of heat and Stockholm was only affected by the first. In this page we will mainly focus on the first period.

Image Added

The plots below shows the evolution of z500 and t850 and analyses spanning from 26 June to 5 July. The plots show the ridge building up from the south-west bringing warm air from north-west Africa to Europe.

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