
Pieter GroenemeijerEuropean Severe Storms Laboratory | ESSL
Pieter Groenemeijer
Dr.
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78
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Introduction
Additional affiliations
December 2011 - present
June 2009 - November 2011
December 2006 - November 2011
Publications
Publications (78)
A climatology of tornadoes (over land and water) is presented, based on the European Severe Weather Database (ESWD), which contains reports of 9529 tornadoes. With the exception of a few small countries, tornadoes have been reported from all regions of Europe. The highest density of tornado reports is in Western and Central Europe. ESWD tornado rep...
The environments of severe and nonsevere thunderstorms were analyzed using 16 421 proximity soundings from December 2007 to December 2013 taken at 32 central European stations. The soundings were assigned severity categories for the following hazards: hail, wind, tornado, and rain. For each of the soundings, parameters were calculated representing...
In the afternoon of 28 July 2005, a damaging F2 tornado in Birmingham, United Kingdom, was one of three tornadoes developing on the immediate cool side of a surface warm front. An analysis is performed to find out why the narrow zone on this side of the front was apparently so favourable for tornadoes in spite of lower surface temperatures. It is i...
The stochastic Plant-Craig scheme for deep convection was implemented in
the COSMO mesoscale model and used for ensemble forecasting. Ensembles
consisting of 100 48 h forecasts at 7 km horizontal resolution were
generated for a 2000 × 2000 km domain covering central Europe.
Forecasts were made for seven case studies and characterized by
different l...
Measurements of a convective storm cluster in the northern Black Forest in southwest Germany have revealed the development of a warm and dry downdraft under its anvil cloud that had an inhibiting effect on the subsequent development of convection. These measurements were made on 12 July 2006 as part of the field campaign Prediction, Identification...
The occurrence of a tornado or some other form of convective wind, of small temporal and spatial scope, is not easily detectable by conventional observations or remote sensing systems. Often its existence is only known a posteriori, based on news and testimonies that must be verified, and records of the maximum wind values reached are very rare. Ho...
We study the role of changes in circulation type frequency on the evolution of summertime thunderstorm and large hail frequency across Europe since 1950 until 2020 to find out if they are responsible for the changes that an additive regression model (AR-CHaMo) predicts to have happened. To define circulation types, the 500 hPa geopotential height a...
Additive logistic regression models for lightning (ARlig) and large hail (ARhail) were developed using convective parameters from the ERA5 reanalysis, hail reports from the European Severe Weather Database (ESWD), and lightning observations from the Met Office Arrival Time Difference network (ATDnet). The models yield the probability of lightning a...
We have developed additive logistic models for the occurrence of lightning, large (≥ 2 cm), and very large (≥ 5 cm) hail to investigate the evolution of these hazards in the past, in the future, and for forecasting applications. The models, trained with lightning observations, hail reports, and predictors from atmospheric reanalysis, assign an hour...
We have developed additive logistic models for the occurrence of lightning, large (≥ 2 cm), and very large (≥ 5 cm) hail to investigate the evolution of these hazards in the past, in the future, and for forecasting applications. The models, trained with lightning observations, hail reports, and predictors from atmospheric reanalysis, assign an hour...
A record-breaking marine heatwave and anthropogenic climate change have substantially contributed to the development of an extremely anomalous and vigorous convective windstorm in August 2022 over the Mediterranean Sea.
Additive Logistic Regression models for lightning and large hail (ARhail) were developed using convective parameters from the ERA5 reanalysis, hail reports from the European Severe Weather Database (ESWD), and lightning observations from the Met Office Arrival Time Difference network (ATDnet). The model yields the probability of large hail in a giv...
The European Storm Forecast Experiment (ESTOFEX) is a well known project of volunteer meteorologists making forecasts of thunderstorms and their severe weather threats for Europe for 20 years (since October 2002). Originally, the forecasts consisted of three severe weather risk lines as well as one thunderstorm line. The verification of the dichoto...
The European Storm Forecast Experiment (ESTOFEX) is a team of volunteer forecasters that have been providing experimental convective outlooks for Europe since 2002. Probabilistic storm forecasts issued by ESTOFEX address threats posed by severe convective storms, i.e. lightning, large hail, severe wind gusts, tornadoes and excessive precipitation....
The Copernicus Ocean State Report is an annual
publication of the Copernicus Marine Service,
established in 2014 by the European Commission for
Copernicus 1 and renewed in 2021 for Copernicus 2.
The report provides a comprehensive, state-of-the-art,
scientific overview on the current conditions, natural
variations, and ongoing changes in the global...
Convective storms develop in both strong and weak vertical wind shear but long-lived, well organised convection requires strong vertical wind shear. Studies have shown that the relative frequency of occurrence of convective hazards such as large hail, severe wind gusts and tornadoes increases with increasing vertical wind shear. A particularly stro...
As lightning-detection records lengthen and the efficiency of severe weather reporting increases, more accurate climatologies of convective hazards can be constructed. In this study we aggregate flashes from the NLDN and ATDnet lightning-detection networks with severe weather reports from ESWD and SPC Storm Data on a common grid of 0.25° and 1-hour...
Globally relevant and locally devastating, hailstorms produce significant societal impacts; despite this, our understanding of hailstorms and our ability to predict them is still limited.
The processes leading to the development of hail and the distribution of these events worldwide are reviewed. Microphysical and physical characteristics of hail development are described to provide context of the notable gaps in our understanding of what drives hail to grow large, or what determines how it falls to the ground. Distributional charac...
Damaging weather events such as lightning, hail, and severe wind gusts are likely to become more common across Europe over the next several decades. Increased global temperatures, high low-level humidity levels and a changing polar jet stream are all associated with anthropogenic climate change; however, the implications of such projected changes i...
This document presents a review of the computation of Convective Available Potential Energy (CAPE) and Convective Inhibition (CIN) from NWP model data.
By 31 December 2018, 39 537 quality-controlled reports of large hail had been submitted to the European Severe Weather Database (ESWD) by volunteers and ESSL. This dataset and the NatCatSERVICE Database of Munich RE jointly allowed us to study the hail hazard and its impacts across Europe over a period spanning multiple decades. We present a spatio...
The climatology of (severe) thunderstorm days is investigated on a pan European scale for the period of 1979-2017. For this purpose, sounding measurements, surface observations, ZEUS and EUCLID lightning data, ERA-Interim reanalysis and severe weather reports are compared and their respective strengths and weaknesses are discussed. The research foc...
A number of extreme weather events (EWEs) have made the resilience of the critical infrastructure of priority concern for infrastructure owners, operators and other decision makers. In this context, the European research project RAIN has studied the EWEs and their impacts upon land-based infrastructure in Europe, and develop a Risk-Based Decision M...
A statistical model for the occurrence of convective hazards was developed and applied to reanalysis data to detect multidecadal trends in hazard frequency. The modeling framework is based on an additive logistic regression for observed hazards that exploits predictors derived from numerical model data. The regression predicts the probability of a...
The occurrence of environmental conditions favorable for severe convective storms was assessed in an ensemble of 14 regional climate models covering Europe and the Mediterranean with a horizontal grid spacing of 0.448. These conditions included the collocated presence of latent instability and strong deep-layer (surface to 500 hPa) wind shear, whic...
The European Severe Storms Laboratory (ESSL) was founded in 2006 to advance the science and forecasting of severe convective storms in Europe. The ESSL was a grass-roots effort of individual scientists from various European countries. The purpose of this article is to describe the ten-year history of ESSL and present a sampling of its successful ac...
The social and economic impact of tornadoes in Europe is analyzed using tornado reports from the European Severe Weather Database between 1950 and 2015. Despite what is often assumed by the general public and even by meteorologists and researchers, tornadoes do occur in Europe and they are associated with injuries, fatalities, and damages, although...
Decadal forecasts of the Max Planck Institute – Earth System Model (MPI-ESM) are validated against ERA-Interim reanalysis data for the period 1979 to 2012 over Europe with respect to (a) the medians of 500 hPa temperature, 925 hPa temperature and 925 hPa mixing ratio, and (b) the 90th percentiles of parameters that are relevant for convective storm...
This report presents analyses of the probability of hydro-meteorological hazard occurrence, which
were carried out within the RAIN project. Those probabilities and their projected changes1 during the
21st century are an input to subsequent risk analyses which assist the identification of optimal
adaptation measures. These data are available at the...
A statistical model was developed for the occurrence of electrified convection across Central Europe, based on ERA-Interim reanalysis data and lightning detection data from the European Cooperation for Lightning Detection. The model was developed by fitting an additive logistic regression to multiple selected physical parameters, whose individual r...
The occurrence and characteristics of mesocyclones in Central Europe as seen by radar are analysed. A three year analysis shows an annual and diurnal cycle with a wider maximum in the late afternoon/evening compared to the diurnal cycle of general thunderstorms. Analysis of F2 tornado events and over a hundred hail storms show the characteristics o...
The relations between lightning occurrence over Europe from the EUCLID network (2008–2013) and
parameters derived from ERA-Interim reanalysis data were studied to increase the understanding of the
conditions under which thunderstorms form. The objective was to identify relevant factors beyond instability
and convective inhibition, in order to bette...
For the development of severe thunderstorm proxies it is crucial to learn how well reanalysis datasets represent the atmospheric conditions. A natural approach is to compare selected reanalysis datasets with observed data. The aim of this study is to detect the strengths and weaknesses of the reanalysis datasets with respect to parameters relevant...
A proxy parameter for the occurrence of electrified convection was developed as a function of several parameters derived from reanalysis data. The objective was to identify relevant factors beyond instability and convective inhibition to increase the understanding of the conditions under which thunderstorms form. Storms may not occur even though th...
This report summarises the work done in 7 FP project EWENT, its first work package.
D1 deliverable introduces a review of extreme weather phenomena and identifies
their impacts and consequences on European transport system. All modes of transport
are covered. Two main methods are used. First, there is an extensive literature
review on extreme weath...
Hailstorms can pose a significant threat to society, by damaging property and disrupting livelihoods. An understanding of how hailstorm characteristics may change under a warming climate is therefore important for assessing the risk of hail damage for the insurance industry. A simple model of hailstone formation has been driven using meteorological...
Verification of multi-categorical thunderstorm forecasts at the European Storm Forecast Experiment over the period 2009-2013
The European Storm Forecast Experiment (ESTOFEX) has been making forecasts of thunderstorms and accompanying severe weather for most of Europe for more than 10 years. The forecasts consisted of three severe weather threat li...
The European Severe Storms Laboratory's (ESSL) aim is to increase
understanding of high-impact weather, with a particular focus on
phenomena with small spatial and temporal dimensions, such as large
hail, convectively-driven severe wind gusts, tornadoes and extreme
precipitation.The ESSL performs and supports research activities and
contributes to...
From 4 June to 6 July 2012, the first ESSL Testbed has taken place at
the Research and Training Centre of the European Severe Storms
Laboratory in Wiener Neustadt, Austria. During this time, researchers
and forecasters worked closely together putting new forecast supporting
products to the test. The Testbed's main activity is to prepare
experimenta...
Thunderstorms and their accompanying phenomena like large hail, severe
wind gusts, tornadoes and excessive precipitation are increasingly
recognized as an important hazard to life and property in Europe. Within
the project STEPCLIM ("Severe Thunderstorm Evaluation and Predictability
in Climate Models"), we link historic severe thunderstorm events i...
Thunderstorm research is strongly motivated by the wish to reduce the
harm they do to people and their property. Thunderstorms are a global
phenomenon, although some areas in the mid-latitudes and tropics are
particularly at risk. They form where and whenever the ingredients for
their formation come together: instability, moisture and lift.
Especia...
The stochastic Plant-Craig scheme for deep convection was implemented in the COSMO mesoscale model and used for ensemble forecasting. Ensembles consisting of 100 48-h forecasts at 7 km horizontal resolution were generated for a 2000×2000 km domain covering central Europe. Forecasts were made for seven case studies characterized by different large-s...
Hail risk models are rare for the insurance industry. This is opposed to
the fact that average annual hail losses can be large and hail dominates
losses for many motor portfolios worldwide. Insufficient observational
data, high spatio-temporal variability and data inhomogenity have
hindered creation of credible models so far. In January 2012, a
sel...
This deliverable of EWENT project estimates the risks of extreme weather on European transport system. The main object of work package 5 in EWENT project was to perform a risk analysis based on impact and probability assessments carried out in earlier work packages (WP2-WP3). The results of WP 5 can be used as a starting point when deciding on the...
Three years of forecasts of lightning and severe thunderstorms from the European Storm Forecast Experiment (ESTOFEX) have been evaluated. The forecasts exhibit higher quality in summer than in winter and there is some evidence that they have improved over the course of the evaluation. Five individual forecasters made the majority of the forecasts a...
We propose an updated wind speed scale description adapted for Central Europe considering wind impact to buildings as well as to vegetation. The scale is motivated by the need of a broadly applicable, accurate and consistent tornado or downburst intensity rating system based on a standardised wind speed scale for the purpose of climatological homog...
This report summarises the work done in 7 FP project EWENT, its first work package. D1 deliverable introduces a review of extreme weather phenomena and identifies their impacts and consequences on European transport system. All modes of transport are covered. Two main methods are used. First, there is an extensive literature review on extreme weath...
Adverse and extreme weather events, such as heavy rain, heavy snowfall, strong winds, extreme heat and cold, drought and reduced visibility, can have a negative impact on the transport sector, causing injuries and damages as well as other economic losses. Fre-quency and intensity of weather and climate extremes are likely to continue to change in t...
Adverse and extreme weather events, such as heavy rain, heavy snowfall, strong winds, extreme heat and cold, drought and reduced
visibility, can have a negative impact on the transport sector, causing injuries and damages as well as other economic losses. Frequency
and intensity of weather and climate extremes are likely to continue to change in th...
Ground-truth quality-controlled data on severe weather occurrence is required for meaningful research on severe weather hazards. Such data are collected by observation networks of several authorities in Europe, most prominently the National Hydrometeorological Institutes (NHMS). However, some events challenge the capabilities of such conventional n...
We have implemented the Plant-Craig (PC) stochastic convection scheme into the limited-area COSMO (Consortium for Small-scale Modeling) model. We have run the model with initial and boundary conditions provided by selected members of the ECMWF Ensemble Prediction System (EPS). This allows us to compare how much ensemble spread is introduced to the...
We report on our efforts to implement a stochastic scheme for deep moist convection into the COSMO (Consortium for Small-scale Modeling) atmospheric model, and use the scheme in simulations with 7 km grid-spacing. A parameterization scheme of deep moist convection aims to represent the net effect of convection occurring on sub-grid scales, i.e. tha...
Severe thunderstorms constitute a major weather hazard in Europe, with an estimated total damage of 5–8 billion euros each year nowadays. Even though there is an upward trend in
damage due to increases in vulnerability and possibly also due to climate change impacts, a pan-European database of severe thunderstorm reports in a homogeneous data forma...
The characteristics of deep moist convection in the troposphere strongly depend on the thermodynamic and kinematic environment in which it occurs. The relative strength of the vertical wind shear in comparison to buoyancy has a strong influence on the dynamics of a convective storm, which has implications for its longevity and severity. By means of...
A study is presented focusing on the potential value of parameters derived from radiosonde data or data from numerical atmospheric models for the forecasting of severe weather associated with convective storms. Parameters have been derived from soundings in the proximity of large hail, tornadoes (including tornadoes over water: waterspouts) and thu...