Convective Outlook 29.04.2018

deutsche Outlook-Kurzfassung (aufklappen)

Forecaster: Kahnert

Morgen fließt vorübergehend warme subtropische Luft nach NRW, die ab dem Abend von einer Kaltfront wieder verdrängt wird. Dabei besteht v.a. in der Südwesthälfte NRWs erhöhtes Unwetterpotential durch Gewitter mit größerem Hagel, schweren Sturmböen und Starkregen. Einige Wettermodelle berechnen sogar ein heftiges Starkwindereignis bei dem orkanartige Böen denkbar wären (beachtet diesbezüglich die graue significant-Schraffur in den Outlook-Karten). Wie stark das Ganze wird, lässt sich aber erst morgen im Tagesverlauf abschätzten. Viel wird davon abhängen, wie lange die Sonne ungestört scheinen und die Luft erwärmen kann. Je länger es vorher einheizt, umso stärker werden die Gewitter.

In jedem Fall werden wir die Lage morgen genau im Auge behalten und natürlich unterwegs sein.

Seid wachsam und verfolgt die Warnungen des Deutschen Wetterdienstes.

UPDATE

Aufgrund verbreiteter mittelhoher Bewölkung und damit reduzierter Einstrahlung (= weniger Energie als erwartet), haben wir unseren Convective Outlook geupdated und den Severe Threat 2 entfernt. Unwetter durch Starkregen, Hagel und schweren Sturmböen sind ab dem Abend weiterhin möglich, nur die Auftretenswahrscheinlichkeit hat sich reduziert. Weiterhin besteht ein High-End Severe Threat 1 für NRW.
Über Frankreich haben sich übrigens die ersten Gewitter entwickelt, die Richtung NRW ziehen.

CategoricalHailWind GustsTornadoHeavy Rain



Risk Area (sq. km) Population Larger Cities in Risk Area
20 % 1.960.377 281.427.976 Amsterdam, Antwerpen, Basel, Belgrade, Berlin, Bordeaux, Bremen, Brussels, Budapest, Cologne, Dortmund, Dresden, Duisburg, Düsseldorf, Essen, Florence, Frankfurt, Geneva, Genoa, Hamburg, Hannover, Katowice, Kraków, Leipzig, Lódz, Lvov, Lyon, Mannheim, Marseille, Milan, Munich, Nice, Nürnberg, Poznan, Prague, Rome, Sarajevo, Sofia, Stuttgart, Toulouse, Turin, Vienna, Vilnius, Warsaw, Wroclaw, Wuppertal, Zagreb, Zurich
50 % 671.549 117.007.984 Budapest, Cologne, Dortmund, Dresden, Duisburg, Düsseldorf, Essen, Genoa, Katowice, Kraków, Lódz, Milan, Poznan, Sarajevo, Turin, Warsaw, Wroclaw, Wuppertal
Severe Threat 1 409.248 94.430.802 Basel, Bremen, Cologne, Dortmund, Dresden, Duisburg, Düsseldorf, Essen, Frankfurt, Genoa, Leipzig, Lyon, Mannheim, Milan, Turin, Wuppertal


Risk Area (sq. km) Population Larger Cities in Risk Area
2 % 1.592.295 240.313.453 Basel, Belgrade, Bremen, Brussels, Budapest, Cologne, Dortmund, Dresden, Duisburg, Düsseldorf, Essen, Florence, Frankfurt, Geneva, Genoa, Hannover, Katowice, Kraków, Leipzig, Lódz, Lyon, Mannheim, Milan, Munich, Nice, Nürnberg, Poznan, Prague, Sarajevo, Stuttgart, Turin, Vienna, Warsaw, Wroclaw, Wuppertal, Zagreb, Zurich
5 % 786.324 136.091.995 Budapest, Cologne, Dortmund, Dresden, Duisburg, Düsseldorf, Essen, Frankfurt, Genoa, Katowice, Kraków, Leipzig, Lódz, Mannheim, Milan, Poznan, Sarajevo, Turin, Warsaw, Wroclaw, Wuppertal
10 % 68.248 23.142.580 Milan

Risk Area (sq. km) Population Larger Cities in Risk Area
2 % 1.144.826 5.182.771.981 Antwerpen, Basel, Bremen, Brussels, Budapest, Cologne, Dortmund, Dresden, Duisburg, Düsseldorf, Essen, Frankfurt, Geneva, Genoa, Hannover, Katowice, Kraków, Leipzig, Lódz, Lyon, Mannheim, Marseille, Milan, Nice, Poznan, Sarajevo, Stuttgart, Turin, Warsaw, Wroclaw, Wuppertal, Zurich
5 % 298.845 66.083.462 Basel, Bremen, Cologne, Dortmund, Duisburg, Düsseldorf, Essen, Frankfurt, Lyon, Mannheim, Wuppertal
10 % 96.568 33.496.316 Cologne, Dortmund, Duisburg, Düsseldorf, Essen, Wuppertal
Significant 53.986 16.013.842 Cologne, Dortmund, Düsseldorf, Wuppertal

Risk Area (sq. km) Population Larger Cities in Risk Area
2 % 87.911 34.242.971 Cologne, Dortmund, Duisburg, Düsseldorf, Essen, Wuppertal

Risk Area (sq. km) Population Larger Cities in Risk Area
5 % 1.616.467 242.009.319 Amsterdam, Antwerpen, Basel, Belgrade, Bremen, Brussels, Budapest, Cologne, Dortmund, Dresden, Duisburg, Düsseldorf, Essen, Florence, Frankfurt, Geneva, Genoa, Hannover, Katowice, Kraków, Leipzig, Lódz, Lyon, Mannheim, Milan, Munich, Nürnberg, Poznan, Prague, Rome, Sarajevo, Stuttgart, Toulouse, Turin, Warsaw, Wroclaw, Wuppertal, Zagreb, Zurich
10 % 409.248 94.430.802 Basel, Bremen, Cologne, Dortmund, Dresden, Duisburg, Düsseldorf, Essen, Frankfurt, Genoa, Leipzig, Lyon, Mannheim, Milan, Turin, Wuppertal
15 % 93.751 33.907.950 Cologne, Dortmund, Duisburg, Düsseldorf, Essen, Wuppertal
bei Fragen zu den Convective Outlooks hilft unsere
Forecast FAQ

Update 1 for Convective Outlook for 2018-04-29

 

A severe Threat 1 has been issued for eastern France, SW Germany and parts of Be-Ne-Lux mainly for severe wind gusts, large hail, excessive precipitation and a tornado event

 

A severe Threat 1 has been issued for parts of eastern Germany mainly for excessive precipitation and an isolated large hail event

 

A Severe Threat 1 has been issued for North Italy, mainly for large hail, excessive precipitation and to a lesser degree for severe wind gusts

Synoptic Setup

A lead upper level trough extends from the Norwegian Sea to western Iberia yielding a south-westerly flow pattern across central Europe. At lower levels, lee cylogenesis north to the Pyrenees creates a week surface low across southern France during the next hours. Coupling with the upper trough results in a baroclinic development. As the emerging low pressure system travels northeastward in a gradually destabilizing atmosphere, well organized convection is likely during Sunday afternoon and night.

Mesoscale Discussion


…E France, Be-Ne-Lux, Germany…

Prefrontal CI is currently in progress south to Reims (Fr). This convection should organize into the expected linear MCS (see original Convective Outlook). Some further, more isolated cells may trigger in front of the approaching system somewhere along the french/belgian borderline.

Concerning the pre-storm environment, 12 UTC soundings confirm a relatively moist BL from E France to SW Germany (specific moistures > 10 g/kg), but mid-level lapse rates seem to be less steep than expected. In addition a lot of debris cloudiness can be observed within the warm sector by the help of satellite data. Although CAPE is still expected to increase up to locally 1000 J/kg, we downgraded to a high end Severe Threat 1. This is for the following reason:

As the lapse rates (and thus CAPE) are less steep than predicted, very strong cold pool organization gets unlikely. This reduces the chance for significant severe wind gusts. In addition, the lower instability does not justify a 15 % hail line anymore (which is necessary for a Severe Threat 2).

There are no significant changes upon the other thunderstorm/threat areas.

…N Italy…

Diurnal heating will lead to CAPE between 500 and 1000 J/kg within a moderate shear environment with veering hodographs (SRH exceeds up to 150 J/kg). In the late afternoon single and multicell convection will trigger along the Alps and somewhere on the Padan plain. The latter is somewhat uncertain but especially UKMO EURO 4 suggest a single supercell storm north of Parma. Overall severe potential satisfies a brief Severe Threat 1

…Parts of eastern Europe/Balkans…

Scattered disorganized storms will initiate within the diurnal cycle. Locally heavy precipitation will be the primary threat, followed by medium size hail. Activity will rapidly diminish after sunset.

 

 

Model consistency, additional remarks

no text

Updated: 30. April 2018, 08:34 — 08:34
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