Kristian Horvath

Meteorological and Hydrological Service · Applied research and modelling

The study provides a detailed analysis of the climate change projections in mean and extreme precipitation across the Dinaric Alps and the Adriatic coastal area until the end of the 21st century. It uses simulations from the extensive EURO-CORDEX regional climate model ensemble to study precipitation changes considering three greenhouse gas concent...

Hail is a significant convective weather hazard, often causing considerable crop and property damage across the world. Although extremely damaging, hail still remains a challenging phenomenon to model and forecast, given the limited computational resolution and the gaps in understanding the processes involved in hail formation. Here, eight hailstor...

The Split wildfire in July 2017, which was one of the most severe wildfires in the history of this Croatian World Heritage Site, is the focus in this study. The Split fire is a good example of a wildfire–urban interface, with unexpected fire behavior including rapid downslope spread to the coastal populated area. This study clarifies the meteorolog...

The Split wildfire in July 2017, which was one of the most severe wildfires in Croatian history of this World Heritage site, is the focus in this study. The Split fire is a good example of wildfire-urban interface, with unexpected fire behavior including rapid downslope spread to the coastal populated area. Thus, it is critical to clarify the meteo...

Information about high-intensity precipitation of short duration and the corresponding return values is of great importance when designing urban drainage systems. In this study, an extreme rainfall event in summer 2020 which caused an urban flood in the city of Zagreb was analyzed from the hydro-meteorological point of view. To put this event in a...

Hailstorms, although extremely damaging severe weather hazards, remain a very challenging phenomenon to predict. To better understand dynamic processes and model performance, which can be helpful in forecasting hailstorms, three selected hailstorms in Croatia are simulated with the WRF model at convection-permitting (1 km) grid spacing using the HA...

One of the Mediterranean hotspots for extreme precipitation is the coastal mountainous eastern Adriatic and Dinaric Alps regions, which are often affected by heavy precipitation events (HPEs) that can cause severe damage. Representing these events at different time scales and projecting their future evolution using regional climate models (RCMs) re...

The main goal of this study is to assess the performance of the analog‐based post‐processing method applied to the Austrian ALADIN‐LAEF wind speed ensemble predictions through a set of sensitivity experiments. Evaluation of several analog‐based configurations using various meteorological variables as predictors is therefore conducted. The results o...

The evaluation of several climatological background-error covariance matrix (defined as the B matrix) estimation methods was performed using the ALADIN limited-area modeling data-assimilation system at a 4 km horizontal grid spacing. The B matrices compared were derived using the standard National Meteorological Center (NMC) and ensemble-based esti...

We analyze atmospheric conditions conducive for a meteotsunami event that occurred in the Adriatic on 25 June 2014. This was the most intensive of a series of meteotsunami events which occurred in the Mediterranean and Black Seas during 23–27 June 2014 period. Considerable sea-level oscillations were observed in several eastern Adriatic harbors wit...

The topical issue includes 22 papers on different aspects of meteorology and climatology of the Mediterranean and Black Seas. The papers are grouped into three categories, based on scale analysis of processes, and whether the study is dominantly related to the atmospheric or oceanic phenomenon. The category ‘‘Storms, Extremes and Mesoscale Processe...

The Mediterranean Sea, as a “centre” of the ancient world, has been early recognized as a laboratory basin for a variety of atmospheric, ocean and climate studies. Its uniqueness is manifested in its geographical position, a mid-latitude region connecting three continents, orography that affects cyclogenesis, precipitation and winds, ocean bathymet...

We analyze atmospheric conditions conducive for a meteotsunami event that occurred in the Adriatic on 25 June 2014. This was the most intensive of a series of meteotsunami events which occurred in the Mediterranean and Black Seas during 23–27 June 2014 period. Considerable sea-level oscillations were observed in several eastern Adriatic harbors wit...

The topical issue includes 22 papers on different aspects of meteorology and climatology of the Mediterranean and Black Seas. The papers are grouped into three categories, based on scale analysis of processes, and whether the study is dominantly related to the atmospheric or oceanic phenomenon. The category “Storms, Extremes and Mesoscale Processes...

Strong winds crossing elevated terrain and descending to its lee occur over mountainous areas worldwide. Winds fulfilling these two criteria are called foehn in this paper although different names exist depending on the region, the sign of the temperature change at onset, and the depth of the overflowing layer. These winds affect the local weather...

The performance of analog-based and Kalman filter (KF) postprocessing methods is tested in climatologically and topographically different regions for point-based wind speed predictions at 10 m above the ground. The results are generated using several configurations of the mesoscale numerical weather prediction model ALADIN. This study shows that de...

Status of operational ALADIN in Croatian meteorological and hydrological service.

The comparison of forecast pressure evolution to the measured data shows that the intensity of the observed pressure disturbances is simulated fairly by the model, but at a slightly different position and time, and propagate with slightly different speed and direction. Meteotsunamis are known to be highly sensitive to these parameters.

HyMeX (HYdrological cycle in the Mediterranean Experiment) experimental activity during the SOP1 (Special Observing Period – 5 September to 6 November 2012) focused mostly on the Western Mediterranean, but many events that affected the Western Mediterranean expanded to the Adriatic area. During SOP1, 16 IOPs were dedicated to heavy precipitation ev...

In this article, we present an overview of the HyIV-CNRS-SecORo (Hydralab IV-CNRS-Secondary Orography and Rotors Experiments) laboratory experiments carried out in the CNRM (Centre National de Recherches Météorologiques) large stratified water flume. The experiments were designed to systematically study the influence of double obstacles on stably s...

The HYdrological cycle in the Mediterranean EXperiment (HyMeX) is intended to improve the capabilities of predicting high-impact weather events. Within its framework, the aim of the first special observation period (SOP1), 5 September to 6 November 2012, was to study heavy precipitation events and flash floods. Here, we present high-impact weather...

The HYdrological cycle in the Mediterranean EXperiment (HyMeX) is intended to improve the capabilities to predict high impact weather events. In its framework, the first Special Observation Period (SOP1), 5 September to 6 November 2012, was aimed to study heavy precipitation events and flash floods. Here we present high impact weather events over C...

Overview of recent operational and research activities on the subjects related to NWP model ALADIN in Croatian Meteorological and Hydrological Service.

Well known for its severity, the bora downslope windstorms have been extensively studied over the last several decades. This study focuses on the turbulence characteristics of bora at a topographically complex site near the eastern coast of the Adriatic Sea. For this purpose, a 3-month eddy-covariance dataset obtained at three levels (10, 22, 40 m)...

The Croatian national poster presented at EWGLAM/SRNWP meeting in 2015.

The operational model domains and computer hardware are explained with short description of recent changes in operational forecast and current developments.

A detailed description of the meteorological conditions of the Washoe Valley (Nevada) and simulations that examine the predictability of the westerly high wind event known as the Washoe Zephyr are presented. Numerical weather model prediction skill is computed for day-ahead (24-48 h) forecasts of wind speed at a meteorological tower on the Virginia...

The article aims to test the sensitivity of high-resolution mesoscale atmospheric model to fairly reproduce atmospheric processes that were present during the Boothbay Harbor meteotsunami on 28 October 2008. The simulations were performed by the Weather and Research Forecasting (WRF) model at 1-km horizontal grid spacing by varying initial conditio...

The aim of this study was to identify the main mesoscale features and mechanisms responsible for the generation of an extreme precipitation event as a contribution to improving the modelling of processes that produce HPEs. The event occurred during the morning hours on 22 November 2010 over the Dubrovnik coast in Croatia and the hinterland mountain...

In recent years rapid growth of wind power generation in many countries around the world has highlighted the importance of wind prediction. In this work neural networks are used for ultra-short-term wind prediction. In many instances reported in the literature neural network exhibit poor performance-very often because no complexity reduction method...

The main issues related to assessment and forecasting of the wind and wind energy have been reviewed. These include the limitations and advantages of wind forecasting and assessment of the wind power density, especially considering trends of increasing penetration of wind-generated power into the utility grid and storage of wind-generated power. Ac...

We investigated the atmospheric processes and physics that were active during a tsunami-like event hitting Boothbay Harbor area (Maine, USA) on 28 October 2008. The data collected by tide gauges, ground and sounding stations and meteo–ocean buoys in the area were analyzed, together with satellite and radar images. The atmospheric processes were rep...

During the past years the modelling community, both from the application and pure research perspectives, has been facing the challenge of high-resolution modelling in places with complex topography. In February 2012, as a result of the collaborative efforts of BOKU-Met, ARSC, IMG and the enthusiasm of the scientific community, the HiRCoT workshop w...

The COST Action ES1002 “Weather Intelligence for Renewable Energies WIRE” was launched in November 2010 to promote the short time forecasts of energy production for wind and solar energy. Its goals are 3-fold: evaluate the accuracy of existing forecast systems (including post processing algorithms) by validating their results with in-situ measureme...

Sub-kilometer dynamical downscaling was performed using the Weather Research and Forecasting (WRF) and Mesoscale Model Version 5 (MM5) models. The models were configured with horizontal grid spacing ranging from 27 km in the outermost telescoping to 333 m in the innermost domains and verified with observations collected at four 50-m towers in west-...

Meteotsunamis, or meteorological tsunamis, are atmospherically induced ocean waves in the tsunami frequency band that are found to affect coasts in a destructive way in a number of places in the World Ocean, including the U.S. coastline. The Boothbay Harbor, Maine, in October 2008 and Daytona Beach, Florida, in July 1992 were hit by several meters...

During the past years the atmospheric modeling community, both from the application and pure research perspectives, has been facing the challenge of high resolution numerical modeling in places with complex topography. In February 2012, as a result of the collaborative efforts of the Institute of Meteorology of the University of Natural Resources a...

The results of numerically modeled wind speed climate, a primary component of wind energy resource assessment in the complex terrain of Croatia, are given. For that purpose, dynamical downscaling of 10 yr (1992-2001) of the 40-yr ECMWF Re-Analysis (ERA-40) was performed to 8-km horizontal grid spacing with the use of a spectral, prognostic full-phy...

Observational data and outputs from the Weather Research and Forecasting (WRF) model are used to investigate a heavy precipitation event that occurred on 12 and 13 November 2004 in Apulia and Basilicata, southeastern Italy. The event lasted for more than 24 h and featured two large rainfall peaks, with values up to 250 mm in one day, recorded in tw...

The applications being developed and used at Meteorological and Hydrological Service of Croatia cover broad areas of meteorology, climatology, renewable energy, hydrology, air quality modeling, and other. Applications used for operational weather forecasting include the numerical weather prediction model ALADIN, data pre- processing and model outpu...

Regional/mesoscale models are often utilized for wind resource estimates, owing to the low spatial and temporal representativeness of routine measurements and global reanalysis. In many applied scientific disciplines including wind engineering, it is often considered that the higher resolution the better, i.e. that increased horizontal resolution o...

A very important source of information in data assimilation is the background, which is usually a short-range forecast of the numerical weather prediction (NWP) model valid at the assimilation time. The background is corrected by the atmospheric observations providing the analysis during the process of data assimilation. Errors of the background ar...

Regional/mesoscale models currently provide useful wind power density products. Besides the traditional use in numerical weather prediction, this type of model is often used for regional wind resource estimates, owing to the low spatial and temporal representativeness of routine measurements. In many applied scientific disciplines including wind en...

The second annual Nevada Renewable Energy Consortium meeting took place at UNLV on August 20. The meeting focused on the current three NVREC program areas: Solar, Biomass and Geothermal. Presentations were made by participating entities and a poster session followed.

Regional/mesoscale models currently provide reliable wind power density products. Besides the traditional use in numerical weather prediction, this type of model is often used for regional wind resource estimates, owing to the low spatial and temporal representativeness of routine measurements. In many applied scientific disciplines including wind...

There is much uncertainty about future climate change and its impact on the environment. In particular, it is crucial to estimate the variability of atmospheric parameters relevant to future hydrological resources. This assessment is further complicated by the unknown future greenhouse gases (GHGs) emissions. While many studies focus on a particula...

A heavy precipitation event affected the Ionian areas of Basilicata and Apulia, in southern Italy, during 12 and 13 November 2004. Two rainfall maxima of about 250 and 145 mm occurred over two different coastal and nearly flat areas. The northern rainfall maximum was generated during the second half of 12 November; it resulted from two intense loca...

While statistical analyses and observations show that severe bora with maximum gusts exceeding 40 m s−1 can occur in all parts of the Adriatic, the bora research to date has been mainly focused on the dynamics and structure of severe bora in the northern Adriatic. Examined to a significantly lesser degree is a less predictable counterpart in the so...

A 12–15 November 2004 cyclone on the lee side of the Atlas Mountains and the related occurrence of severe bora along the eastern Adriatic coast are numerically analyzed using the MM5 mesoscale model. Motivated by the fact that sub-synoptic scales are more sensitive to initialization errors and dominate forecast error growth, this study is designed...

Global model reanalysis or forecast data needs to be downscaled to provide information for regional interpretation. This is especially true in complex terrain of Croatia, where a significant portion of the wind energy potential is related with phenomena resulting from the interaction of the mountains and the lower troposphere, such as Bora, the loc...

Cyclones that appear in the basin of Adriatic Sea strongly influence the climate and weather conditions in the area. It is therefore crucial to classify the different cyclone types in the area since it enhances the understanding and prediction of the related phenomena. In this study, based on the analysis of four year (2002 - 2005) operational ECMW...

Most of the Bora research to date has been focused on the dynamics and structure of severe Bora in the northern Adriatic. Significantly less studied is the Bora in the southern Adriatic, where the Dinaric Alps are higher and broader and the upwind Bora layer is generally less well defined. Statistical analysis and observations show that a severe Bo...

Bora that happened on 14 November 2004 was one of the most severe ever measured, causing significant human, economic and infrastructural losses. Except for its intensity, the particularities of this event were the severe Bora longevity (~24hr) and simultaneous coexistence on Northern and Southern Adriatic. The synoptic setting was characterized wit...

This paper presents the first results of a climatologically representative spatial distribution of wind speed, a primary component of wind resource assessment in the complex terrain of Croatia. For this purpose, a dynamical downscaling of ERA-40 reanalysis was performed to an 8-km horizontal grid resolution, using the ALADIN spectral prognostic mod...

The initiation of a deep and severe impact Mediterranean cyclone in the lee of Atlas Mountains is investigated by a series of numerical experiments using the MM5 forecast model. Roles of orography, surface sensible heat flux and an upper-level potential vorticity anomaly are identified using factor separation method. Results of model simulations sh...

The initiation of a deep and severe impact Mediterranean cyclone in the lee of the Atlas Mountains is investigated by a series of numerical experiments using the MM5 forecast model. The roles of orography, surface sensible heat flux and upper-level potential vorticity anomaly are identified using the factor separation method. In addition, a sensiti...

In order to explore potential to predict local wind climate ALADIN/HR mesoscale model was coupled with the local-scale wind resource numerical model WAsP. Time series of predicted geostrophic wind at 850 hPa were calculated by the mesoscale model ALADIN/HR and used to extract wind atlas files readable by WAsP. WAsP was forced to downscale geostroph...

The deep cyclogenesis causing a range of severe weather events took place over the Mediterranean Sea from 11- 15 November 2004. The first phase of the event was analysed by a series of numerical experiments using the MM5 forecast model. Factor separation method was applied to investigate the cyclogenetic and cyclolytic influences of orography, uppe...

The Atmospheric Lagrangian Particle Stochastic (ALPS) dispersion mo-del was created as an experimental student project and tested under ideal-ized and complex atmospheric and topographic conditions. The challenge of the project was to bring current scientific technology to the direct involve-ment of students in the framework of problem based learni...

The Atmospheric Lagrangian Particle Stochastic (ALPS) dispersion model was created as an experimental student project and tested under idealized and complex atmospheric and topographic conditions. The challenge of the project was to bring current scientific technology to the direct involvement of students in the framework of problem based learning...

The time series of temperature, wind speed and wind direction of the ALADIN/LACE (Limited Area Modelling for Central Europe) mesoscale model were compared with the radio-sounding data obtained above Zagreb during the Mesoscale Alpine Programme Special Observing Period (MAP SOP, Sept-Nov 1999). The evaluation was done at the 850 hPa level and at 988...