European Storm Forecast Experiment A close look at a severe MCS during the Kyrill winter storm over...

European Storm Forecast Experiment

A close look at a severe MCS during the „Kyrill“ winter storm over Central Europe

Christoph Gatzen, Pieter Groenemeijer, Oscar van der Velde,

Jan Hoffmann, Angel Dimitrov, Helge Tuschy, Johannes Dahl


• Ingredients-based theory

18 Jan

12 Z..

15 Z..

18 Z


• Ingredients-based theory

18 Jan

12 Z..

15 Z..

18 Z

?


• Estofex discussion: Ahead of the cold front…• Instability

• Neutral/slightly moist-unstable lapse rates and rich low-level moisture• At least minimal, but positive CAPE, even at low levels

• Forcing• Strong QG forcing, low-level convergence, initiation along cold front

• Shear• Strong vertical wind shear, favorable veering (SRH 0-1km ~800 J/kg)

• Expected Scenarios

1. Weak instability: Strongly-forced convective line along the cold front moving eastward. High winds the main threat, tornadoes possible

1. Significant CAPE: Well-developed MCS, cold pool and associated low level jets. Extremely high wind gusts at the leading gust front, tornadoes possible


• Estofex discussion: Ahead of the cold front…• Instability

• Neutral/slightly moist-unstable lapse rates and rich low-level moisture• At least minimal, but positive CAPE, even at low levels

• Forcing• Strong QG forcing, low-level convergence

• Shear• Strong vertical wind shear, favorable veering (SRH 0-1km ~800 J/kg)

• Expected Scenarios

1. Weak instability: Strongly-forced convective line along the cold front moving eastward. High winds the main threat, tornadoes possible

1. Significant CAPE: Well-developed MCS, cold pool and associated low level jets. Extremely high wind gusts at the leading gust front, tornadoes possible


• The Kyrill Storm: Satellite view

Hourly images:

18 Jan

08 Z..

19 Jan

00 Z

MSG

WV6.2-WV7.3 IR9.7-IR10.8

WV6.2i

copyright 2007 EUMETSAT


• Associated MCS: Lightning

copyright 2007 EUMETSAT © DWD/Siemens AG 2007

15, 16, 17, 19 Z


• Associated MCS: Radar composit

copyright 2007 EUMETSAT © DWD 2007

12 - 20 Z, radar ¼-hourly


• Associated MCS: Radar composit


18 Z


• Associated MCS: Cold pool evolution

LMK, surface observations © DWD 2007

16 - 20 Z


• How did instability develop?


• High low-level winds ahead of the front

LMK – Analysis 800 hPa winds at 18 Z WindprofilerBayreuth, 14-23 Z


• Tornado occurrence over Germany

Berlin

Dresden

Tornados occurred at the eastern flank of the cold pool, where low-level winds likely shifted towards the south

• strengthen of low-level veering

• increase of low-level convergence

• also increase of instability due to cool westerly flow

overspreading the warm air mass as LMK suggests


• Doppler radar observations: Dresden


• Vertical cross section


• The tornadic supercell near Lauchhammer

WER


• The tornadic supercell near Lauchhammer


• Thanks!


12 - 20 Z, radar ¼-hourly

European Storm Forecast Experiment A close look at a severe MCS during the Kyrill winter storm over...

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