Tornadoes in Romania

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Tornadoes in Romania

BOGDAN ANTONESCU

Centre for Atmospheric Science, School of Earth, Atmospheric and Environmental Sciences, University of

Manchester, Manchester, United Kingdom

AURORA BELL

Bureau of Meteorology, Melbourne, Victoria, Australia

(Manuscript received 2 June 2014, in final form 23 September 2014)

ABSTRACT

The first tornado climatology for Romania is presented based on datasets attained from three periods

between 1822 and 2013. The historical period (1822–1944) contains 33 tornado reports originating fromhistorical newspaper archives and publications of the Romanian Meteorological Institute. Evidence of tor-nado observations in Romania before the nineteenth century is found in the representation of tornadoes inthe Romania folk mythology. The socialist period (1945–89) contains only seven tornado reports, likely be-cause during this period it was believed that tornadoes did not occur in Romania. The recent period (1990–2013) contains 89 tornado reports that came from mass-media sources and eyewitness reports. Of the 129

tornadoes from the Romanian tornado database, 98 were reported between May and July with a peak in May(36 reports). Most of the tornadoes (28 reports) occurred during the afternoon hours 1500–1659 local time.Tornadoeswere more frequently reported over eastern Romania compared with other regions of the country,with a maximum over southeastern Romania [0.37–0.45 (105 km2)21 yr21].

1. Introduction

Tornado climatologies are important for understand-

ing the formation and characteristics of severe convective

storms, and also for better quantifying the risks that tor-

nadoes pose. The reported frequencies of tornadoes

are, in general, lower in Europe compared to the

United States. In his study on tornadoes and water-

spouts in Europe, Alfred Wegener estimated that at

least 100 tornadoes occur each year in Europe

(Wegener 1917). More recently, Dotzek (2003) esti-

mated that 329 tornadoes and waterspouts are ob-

served each year in Europe, based on a survey amongthe participants of the Second European Conferenceon Severe Storms. Groenemeijer and Kühne (2014)

showed, based on the data from the European SevereWeather Database (Dotzek et al. 2009) between 2006

and 2013, that the average annual number of torna-

does and waterspouts in Europe is 483, representing

4.8 (105 km2)21. By comparison, the average annual

number of tornadoes (no waterspouts) in the United

States between 2006 and 2013 was 1228, representing

12.5 (105 km2)21, based on the National Oceanic and

Atmospheric Administration publication Storm Data

(e.g., Smith et al. 2012; Thompson et al. 2012). Al-

though the threat is apparently smaller in Europe

compared with the United States, the true magnitude

of the tornado threat in Europe is not known because of the lack of assembled datasets. Despite their impor-

tance, it was only recently that some of the European

countries started a systematic documentation of tor-

nado events and developed tornado climatologies.

Tornado climatologies have been published for 14 (32%)

of the 44 countries that have their capital city within

Europe, covering approximately 2 958 988 km2 (30%)

of the European surface area (9 930 054 km2). The

European tornado climatologies mainly focused

on northern, southern, and western Europe and, to

Denotes Open Access content.

Corresponding author address: Dr. Bogdan Antonescu, Centre

for Atmospheric Science, School of Earth, Atmospheric and En-vironmental Sciences, University of Manchester, Simon Building,Oxford Road, Manchester M13 9PL, United Kingdom.E-mail: [email protected]

VOLUME 143 M O N T H L Y W E A T H E R R E V I E W MARCH 2015

DOI: 10.1175/MWR-D-14-00181.1

2015 American Meteorological Society 689

mailto:[email protected]:[email protected]


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a lesser extent, on eastern Europe (e.g., Szilárd 2007;Brázdil et al. 2012; Simeonov et al. 2013) (Fig. 1 and

Table 1).

For Hungary, Szilárd (2007) developed a synoptic

climatology of damaging tornadoes (defined as torna-

does producing any type of damage) reported between

1990 and 2001. Before 1990, damaging tornadoes were

estimated to occur less than once in a decade. Between

1990 and 2001, 36 tornadoes were reported, of which 18

were damaging tornadoes. The increase in the number

of tornado reports after 1990 was attributed to an in-

crease of vulnerability of society and industry, an in-

crease in the public awareness and also to a ‘‘possibleintensification of convective activity (among [those]

years were record hot summers)’’ (Szilárd 2007, p. 264).

Brázdil et al. (2012) analyzed the spatial and temporal

distribution of tornadoes in Czech land (recent Czech

Republic) from 1119 to 2010. During this, period 307

tornadoes occurred in 264 tornado days (defined as the

days in which a least one tornado was reported). Before

1500 A.D., a total of four tornadoes were reported, and

between 11 and 16 tornadoes were reported for each

century up to 1800. A maximum in the number of

tornado reports was observed between 1931 and 1940(44 tornado reports) and another maximum in 2001–10

(56 tornado reports). The recent increase in the number

of tornado reports was attributed to the ‘‘availability of

relevant sources as well as increased social awareness

and advances in communication technology’’ (Brázdil

et al. 2012, p. 193).

Simeonov et al. (2013) analyzed the tornado reports

for Bulgaria and showed that 57 tornadoes occurred in

51 days between 1956 and 2010. The majority of torna-

does were reported after 1990 (45 reports). For a period

of 35 yr between 1956 and 1990, only 12 tornadoes were

reported in Bulgaria. During this period ‘‘most people inBulgaria thought that tornadoes were exotic and not

typical events for [the] country’’ (Simeonov et al. 2013,

p. 62). The increase in the number of tornadoes after

1990 was attributed to the development of communi-

cations and the Internet, which made available the tor-

nado reports collected by amateurs.

The aim of this article is contribute to the climatology

of tornadoes in Europe by presenting the first tornado

climatology for Romania, a country with a long history

of meteorological observations in eastern Europe (the

FIG. 1. The spatial distribution of tornado climatologies in Europe. The countries for which tornado climatologieshave been published (Table 1) are represented in green, and the climatologies for eastern Europe are labeled.Romania is represented in orange.

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Romanian Meteorological Institute was founded in 1884)

(Fig. 1). This article is structured as follows. Section 2describes the Romanian tornado database. The spatial

distribution of tornado reports is described in section 3.

The monthly and diurnal distributions of tornado reports

are discussed in sections 4 and 5, respectively. Finally,

section 6 summarizes the results of this paper.

2. Data

The definition of a tornado used in this article has

been adopted from the Glossary of Meteorology

(Glickman 2000). Thus, a tornado is defined as ‘‘a vio-

lently rotating column of air, in contact with the ground,

either pendant from a cumuliform cloud or underneath

a cumuliform cloud, and often (but not always) visible as

a funnel cloud’’ (Glickman 2000, p. 781). In this article,

the definition was extended by considering all the wa-

terspouts that hit the land as tornadoes, consistent with

the tornado definitions used in other European countries

(e.g., Rauhala et al. 2012). This definition of a tornadowas used by the Romanian National Meteorological

Administration (RNMA) since 2005. The intensity of all

tornadoes in the Romanian tornado database was as-

sessed following the approach of Rauhala et al. (2012),

based on (i) the Fujita scale [F scale; Fujita (1981)] and

(ii) guidance for assigning tornado damage to buildings

[Table 4 in Minor et al.(1977); appendix C in Bunting and

Smith (1993)].

The climatology of tornadoes in Romania was divided

into three periods. The first period, comprising the

historical database, starts in 1822 and ends in 1944 when

Romania became a socialist country (section 2a). Thesecond period contains only seven tornado reports for

an interval of 55 yr between 1945 and 1989. The third

period contains the tornado reports between 1990 and

2013, the period during which the RNMA has been

collecting and analyzing tornadoes reports in Romania

(section 2c).

a. Historical tornado reports

The first tornado report in Romania is from the be-

ginning of the nineteenth century, but tornadoes have

been observed before, as is shown by the Romanian folk

mythology related to the figure of the ‘‘dragon’’ (balaur

in Romanian) and the ‘‘sorcerer’’ ( solomonar in Ro-

manian). For the folk mentality, the dragon is the

Principal of Disorder, which disturbs the order of nature

and human communities by bringing thunderstorms and

hail. The ‘‘solomonar,’’1 the Principle of Order, is

a sorcerer that has the power to control the weather

elements and to subdue the dragon (Oişteanu 2013). Inthe folklore of other countries, high winds and severe

storms also had supernatural representations or were

interpreted as divine judgment [e.g., Jankovic (2000), for

United Kingdom]. We conjecture that tornadoes have

been represented in the Romanian folk mythology as

TABLE 1. Climatologies of tornadoes for European regions. The European regions are based on the definition from the United NationsStatistics Division (available online at http://unstats.un.org/unsd/methods/m49/m49regin.htm). The tornado climatology for Turkey was

also included since Turkey is a contiguous transcontinental country, located in western Asia and southeastern Europe.

Region Country Study Study period

Northern Europe Finland Rauhala et al. (2012) 1796–2007Sweden Peterson (2000) 1725–1996

Lithuania Marcinoniene (2003) 1950–2002Estonia Tooming (2002) 1795–2001Ireland Tyrrell (2003) 1950–2001United Kingdom Holden and Wright (2004) 1091–1999

Western Europe Germany Dotzek (2001) 1587–1999Austria Holzer (2001) 1910–99France Paul (2001) 1680–1999

Southern Europe Italy Peterson (1998) 1456–1992

Giaiotti et al. (2007) 1991–99Spain Gayà (2011) 1825–2009Portugal Leitão (2003) 1936–2002Greece Matsangouras et al. (2014) 1709–2012Turkey Kahraman and Markowski (2014) 1818–2013

Eastern Europe Czech Republic Setvák et al. (2003) 1119–2002Brázdil et al. (2012) 1119–2010

Hungary Szilárd (2007) 1996–2001Bulgaria Simeonov et al. (2013) 1956–2010

1 The term is quite recent and is documented approximatelybetween 1650 and 1750 in Transylvania, central Romania(Oişteanu 2013).

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‘‘balauri’’ [‘‘ale,’’ or ‘‘hale’’ in southern Romania;Haşdeu (1887)]. The description of the dragons varies

from one region to another, but with some common

characteristics. Thus, the dragon has a long tail ‘‘swinging

when it is up into the cloud’’ (representing the funnel

cloud) and ‘‘slapping with a loud noise when it is touching

the ground’’ (representing the tornado itself); the

dragon’s head is either the head of a crocodile or the head

of a horse (representing the anvil of the cumulonimbus

cloud); the dragon’s breath ‘‘is so cold that [it] is freezing

the water in the clouds’’ thus producing large hail

(sometimes associated with tornadic events); the dragon

is also able to ‘‘lift people up into the clouds’’ ( Marian1878a,b; Pamfile 1915, 1916; Gherman 1928; Rezuş 1972).

Sometimes the dragon takes the form of a winged white

horse, which the solomonar rides through the clouds

(Ionitxa 1982). These winged horses ridden by sorcerers

with meteorological powers are also mentioned in Serbo-

Croatian mythology [‘‘graboncijas dijak’’; Jagic (1877)].

Thus, tornadoes were not unknown events in Romania

before the nineteenth century, as shown by the geo-

graphical distribution of the folklore sources in which

the tornadoes are mentioned as balauri (Fig. 2). For

southeastern Romania, no folklore sources could beidentified in which tornadoes are represented as dragons,2

despite the fact that a large number of the tornadoes in the

recent period are reported in this region.

The first historical report of a tornado in Romania is

from 4 June 1822 and occurred in Banat (near Timişoara

in Fig. 2). The severe storm, described as a whirlwind, hit

several villages and destroyed houses and churches and

uprooted or snapped large trees, the damages being

evaluated at approximately 90,0000 florins [approxi-

mately $1 million (U.S. dollars) in 2014] (Dudaş 2006,

p. 45). Most of the historical tornado reports came from

newspaper archives. To find these reports, newspapersbetween 18293 and 1944 were studied using archives

from the Digital Library of Bucharest (http://www.

dacoromanica.ro) and the Digital Library of the

FIG. 2. The topography of Romania and the spatial distribution of the folklore sources in which the tornadoes arementioned as balauri (yellow circles). The major cities in Romania (with populations greater than 280 000) are

represented by the black circles. Other cities referenced in this article are represented by white circles.

2 ‘‘Volbura’’ is another term used to described whirlwind eventsover southeastern Romania (Gherman 1928), but this term is used

in the folklore sources to describe dust whirls (i.e., dust devils) andnot tornadoes.

3 The first Romanian newspapers, Albina Româneasca andCurierul Românesc, were first published in 1829.


http://www.dacoromanica.ro/http://www.dacoromanica.ro/http://www.dacoromanica.ro/http://www.dacoromanica.ro/


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Central University Library of Cluj-Napoca (http://

dspace.bcucluj.ro/). National (e.g., Adevarul , Albina

Româneasca, Curierul Românesc, Epoca, Scânteia) and

local (e.g., Albina Carpat xilor , Clujul , Gazeta de Tran-

silvania) newspapers were studied using keyword

searches for ‘‘tromba’’ (from the French trombe or the

Italian tromba word for tornado) [e.g., Hepites (1887)used the term ‘‘tromba’’ to describe the 9 June 1886

Bucharest tornado], ‘‘uragan/orcan’’ (from the French

ouragan or the German orkan for strong windstorms)

[e.g., Hepites (1904) used the term uragan to describe

the 29 June 1904 Moscow tornado], ‘‘tornada’’ (tor-

nado), and ‘‘vârtej’’ (whirlwind). This keyword search

resulted in approximately 2690 archive entries, which

were then analyzed individually to identify tornado

events based on the information from the newspaper

article (e.g., description of an event and its damage,

eyewitness reports, location, and time of occurrence).

Thus, 16 tornado reports (48.5%) of the 33 reportsfrom the historical dataset are from newspaper articles

(Fig. 3). The most significant tornadic event retrieved

from the newspaper archives is a tornado ranked as

a category 3 (F3) event on the Fujita scale that oc-

curred on 13 May 1912. The tornado killed six peopleand injured more than 50 others, and caused extensive

damage to five villages near Dej, central Romania

(Fig. 2).

Tornado reports were also collected from Annals of

the Romanian Meteorological Institute (14 reports),

marginalia [2 reports; Dudaş (2006)], and memoirs

[1 report; Michelet (1916)]. The Annals, published be-tween 1886 and 1915, contained monthly summaries of

meteorological data and descriptions, as well as case

studies of significant weather events. The first case study

of a tornado in Romania, describing the 9 June 1886

tornado that hit Bucharest, was published in the second

issue of the Annals (Hepites 1887). The tornado oc-

curred close to the Meteorological Institute, thus al-

lowing detailed observations. At least three houses were

completely destroyed, and one person was killed by the

tornado that occurred between 1700 and 1800 LT (1500–

1600 UTC). At the Meteorological Institute, situated

approximately 9 km from the area most affected by thetornado, the wind changed from easterly to northeast-

erly and reached a maximum speed of 15 m s21 during

the passage of the storm, which also produced hail with

a diameter of 2 cm. A damage survey was conducted by

Ştefan Hepites, the first director of the Meteorological

Institute, wherein the damages were estimated at

200,000 francs [approximately $800,000 (U.S. dollars) in

2014].

There are a series of limitations with the historical

tornado dataset. Thus, not all the newspapers (in

particular, local newspapers) published between 1822 and

1944 were available for analysis. Compared with a tor-

nado damage surveys, a tornado report retrieved from

a newspaper contains a limited description of the event.

This could result in location and time errors. Also, tor-nado reports were collected by the Meteorological In-

stitute between 1884 and 1915. In 1916, Romania declared

war on Austria–Hungary, thus formally entering World

War I, and the Meteorological Institute ceased all activi-

ties due to shortage of staff. The activity of the Meteo-

rological Institute was fully restored in 1920, but without

any official publications until the 1950s.

b. Tornado reports during socialist period

For the socialist period (1945–89), only seven tornado

reports were included in the database (Fig. 3). Two re-

ports came from the monthly meteorological bulletin

published by the Meteorological Institute. In the 1960s,

two tornadoes were documented in the meteorological

observers notebooks, but because they were considered

erroneous observations, they were not included in the

official reports. The keyword search in the digital

newspaper archives between 1945 and 1989, using the

same methodology as for the historical period, resultedin only two tornado reports. The lack of tornado reports

during the socialist period can be a result of the fact that

in the 1970s and 1980s, the word tornado was forbidden in

the official meteorological reports and in the mass media

reports, despite the previous observations of tornadoes in

Romania. During this period, the senior meteorologists

considered that tornadoes do not occur in Romania be-

cause the country is situated too far north (approximately

458N), and ‘‘thus the Coriolis effect will not allow the

formation of tornadoes,’’ which are ‘‘confined to the

FIG. 3. The distribution of tornado reports per decade between1822 and 2013. The first decade includes 1822–29 and the last de-cade includes 2010–13.


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tropics’’ (Lemon et al. 2003).4 All the tornadic events

during this period were described as high-wind events,

thus not recognizing the threat of tornadoes. This situa-

tion is what Doswell (2003) described as a self-fulfilling

prophecy: denying the existence of tornadoes in Romania

resulted in no record keeping for such events, and when

tornadoes were observed, they were not reported. Asimilar situation was described by Setvák et al. (2003) for

the Czech Republic. Another source of tornado reports

for this period is the eyewitness reports received at the

Meteorological Institute after 2002. Thus, one report was

included in the database based on the interview with the

eyewitness.

c. Recent tornado reports

After the fall of the Iron Curtain and the Romanian

Revolution in 1989, there was no formal recognition that

tornadoes can occur in Romania. This situation changed

in August 2002 when an F31 long-track tornado cross-ing through southeastern Romania was responsible for

at least three fatalities and the destruction of 33 houses

mainly in the village of Facaeni (Lemon et al. 2003).

Although this was not the first F3 tornado documented

in Romania, it was the first F31 tornado whose parentstorm circulation was observed with the new Romanian

Doppler radar network installed in 2002. The radar net-

work comprised five Weather Surveillance Radar-1998

Doppler (WSR-98D) S-band radars and three existing

C-band radars (Ioana et al.2004). The data provided by the

Romanian radar network and the radar-data algorithms

for mesocyclones (Mitchell et al. 1998) and tornadodetection (Stumpf et al. 1998) were successfully used in

2005 to issue the first tornado warning in Romania

(Teittinen and Schultz 2008). After 2005, a systematic

documentation and analysis of tornado reports was

started at the RNMA with the aim of developing a tor-

nado database for Romania.

Of the 89 tornadoes reported between 1990 and 2013,

85 reports were obtained from mass-media sources and

4 reports were eyewitness reports submitted to the

RNMA. A mass-media report was confirmed if (i)

a photo or a video of the tornado was available (40 re-

ports, 45.0% of all recent reports), (ii) a photo or a videoshowing typically tornado damage and interviews with

the credible eyewitnesses were available (26 reports,

29.2%), or (iii) a damage survey or a cases study was

conducted by the RNMA (19 reports, 21.3% of all recent

reports). The eyewitness reports were submitted by pro-

fessional meteorologists (two reports, 2.2% of all recent

reports) and severe weather spotters (two reports, 2.2%

of all recent reports). Radar and satellite data were an-

alyzed for all the tornado reports after 2002 to confirm

that the radar imagery showed radar echoes or the sat-

ellite imagery showed cloudiness during or after the timeof the event. Even with a verification system in place,

there are limitations to the correctness of the tornado

reporting. Thus, not all the recent tornado reports were

well correlated with the cell locations from the radar data.

These differences were associated with locations errors

(e.g., location of the nearest village was provided instead

of the actual location of the tornado) and time errors

(e.g., only an estimate of the actual time of the tornado

was provided).

Altogether, 129 tornadoes that occurred on 112 days

have been reported in Romania between 1822 and 2013.

The majority of the tornadoes occurred over land (121reports) and eight tornadoes occurred first over water

and then hit the land. Certainly, this dataset is in-

complete, as shown for example by the low number of

tornado reports during the socialist period. The Roma-

nian tornado dataset is clearly dominated by recentevents, with an increase in the number of reports after

the year 2000 (Fig. 3). This increase in the number of

tornado reports was observed in other European coun-

tries, too. For example, for Finland, Rauhala et al.

(2012) showed an increase from 50 tornado reports be-

tween 1990 and 1999, to 130 reports between 2000 and

2007. For Romania, the recent increase in the number of tornado reports can be attributed to

1) increased public awareness after the Facaeni F31

tornado in 2002;

2) implementation of the WSR-98D radar network in

2002 (Ioana et al. 2004) helped in defining tornado

locations considerably, especially in underpopu-

lated areas, by detecting the larger circulation

pattern in which the tornado was embedded (i.e.,

the mesocyclone);

3) a rapid increase in cellular telephone subscriptions

per 100 inhabitants from 11.2 in 2000 to 105.0 in 2012,along with a rapid increase in the percentage of

individuals using the Internet from 3.7 in 2000 to 50.0

in 2012;5

4) volunteer severe weather spotters, some of them

trained by the RNMA (e.g., the Association for

4 This explanation can also resultfrom theconfusionbetween theword ‘‘uragan’’ used to describe tornadoes in the historical data-base and the use of the word in modern Romanian to describetropical cyclones.

5 Source is the World Telecommunication/Information andCommunication Technologies Indicators Database (2013) (avail-able online at http://www.itu.int/en/ITU-D/Statistics/Pages/stat/default.aspx).


http://www.itu.int/en/ITU-D/Statistics/Pages/stat/default.aspxhttp://www.itu.int/en/ITU-D/Statistics/Pages/stat/default.aspxhttp://www.itu.int/en/ITU-D/Statistics/Pages/stat/default.aspxhttp://www.itu.int/en/ITU-D/Statistics/Pages/stat/default.aspx


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Monitoring Severe Weather Phenomena was founded

in 2010); and

5) the ‘‘Twister effect’’ hypothesized by Rauhala et al.

(2012) in which the movie Twister (released in 1996)

and documentary reality television series about

tornadoes (e.g., Storm Chasers that premiered in

2007) resulted in an increased awareness among thepublic about tornadoes.

3. Spatial distribution

The spatial distribution of tornadoes reports in

Romania is shown in Fig. 4. The distribution of tornado

reports during the historical period reflects the avail-

ability of documentary sources rather than the true

distribution. Thus, the majority of tornadoes (29 reports

representing 87.9% of all historical reports) were re-

ported over southern and eastern Romania, a region

that between 1881 and 1913 was the Romanian King-dom. The region of Romania bounded to the east and

south by the Carpathian Mountain Range was a part of

the Austro–Hungarian Empire before 1918, and no of-

ficial reports for this region were available before 1920

(Fig. 4a).Figure 5 shows the distribution of all tornado reports

between 1822 and 2013 by F scale, in which the F-scale

estimate is the minimum that can be retrieved from the

description of the event. From the 23 historical reports

for which an estimation on the F scale was possible, 11

reports were for weak tornadoes [F0 or F1; Hales (1988)]

and 12 reports were for significant tornadoes (F2 or F3).The large percentage of significant tornadoes during the

historical period compared with the other periods is be-

cause strong tornadoes have a large impact on society and

are therefore more likely to be reported than weak tor-

nadoes (Brooks and Doswell 2001; Verbout et al. 2006).

During the socialist period, the annual average number

of tornadoreports decreased from0.44 (105 km2)21 (yr)21

between 1879 and 1913 to 0.06 (105 km2)21 (yr)21 be-

tween 1945 and 1989. All the tornadoes reported during

the socialist period, with one exception (the 12 June 1961

tornado from Cluj), occurred over eastern and southern

Romania (Fig. 4b). The lack of tornado reports is anartifact of the socialist period and not the result of cli-

matological factors. For example, Iliescu (1989) showed,

based on cloud-to-ground (CG) lightning data between

1966 and 1980, gathered using CG lightning counters,

that the annual average number of thunderstorm days

(days in which at least 15 CG lightning flashes were

detected) varies from 35 to 40 thunderstorm days over

most parts of Romania to 25–30 days over southeastern

Romania [Fig. 21 in Iliescu (1989), p. 87]. Geicu and

Cândea (2008), using data from the Romanian surface

FIG. 4. Spatial distribution of (a) historical tornado reports (33

reports between 1822 and 1944), (b) tornado reports during thesocialist period (7 reports between 1945 and 1989), and (c) recenttornado reports (89 reports between 1990 and 2013) in Romania.Tornadoeswereclassified accordingto their intensityon theF scalefor weak tornadoes (F0 or F1) (yellow) and significant tornadoes

(F2 and F3) (red). Tornadoes for which an estimation of the in-tensity was not possible are represented in blue.



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observation network collected between 1961 and 2000,

showed that the annual average number of thunder-storm days over Romania varies from 30 to 40 days.

Thus, the annual average number of thunderstorm days

is not lower during the socialist period compared with

the average between 1961 and 2010.

For the recent period, the annual average number of tornado reports increased compared with the previous

periods to 1.55 (105 km2)21 (yr)21 between 1990 and

2013. The tornado reports are most frequent for the low

elevations over southern and eastern Romania with

a maximum over southeastern Romania (Fig. 4c). From

the 41 recent reports for which an estimate of the F scale

was possible, 68.3% (28 reports) were for F0 tornadoes,24.4% (10 reports) were for F1 tornadoes, and 7.3%

(3 reports) for F2 or F3 (Fig. 5). The small percentage of

significant tornadoes during the recent period can be at-

tributed to a more efficient collection of tornado reports

(particular those for weak tornadoes) and to an increased

awareness among the public. Similarly, Rauhala et al.

(2012) showed that the 29% of the tornado reports in

Finland between 1796 and 1996 were for significant tor-

nadoes, and only 4% of the reports between 1997 and

2007 were for significant tornadoes.

Figure 6a shows the average number of tornadoes per

105 kilometers squared per year based on the tornadoreports between 1822 and 2013 using kernel density es-

timation (KDE). The KDE for a spatial point pattern

(i.e., tornado locations) assumes that the spatial pattern

has densities at every location, rather than only at the

locations where the events were reported (e.g., Dixon

et al. 2011; Brooks et al. 2003a). In this article,

a Gaussian kernel with a bandwidth of 50 km (compa-

rable with the area for which the RNMA issues severe

weather warnings) was used. The 50-km KDE, calcu-

lated on a 10-km output grid to produce a smooth map,

shows that the average number of tornadoes is between

0.30 and 0.45 (105 km2)21 (yr)21 [approximately 1.5–2.25

(105 km2)21 every 5 yr] over northeastern and south-

eastern Romania, and is lower than 0.22 (105 km2)21 (yr)21

(approximately 1.1 tornadoes every 5 yr) over most of

Romania (Fig. 6a).

The high number of tornadoes over northeasternRomania can be attributed to the population density

across this region, with high population density resulting

in more tornadoes being reported. Figure 6b shows,

based on data from the Romania National Institute of

Statistics, that the population density in 2003 over

northeastern Romania was greater than 100 people per

kilometer squared. The high number of tornadoes over

southeastern Romania (maximum over Romania) can-

not be entirely attributed to the population density.

Compared with northeastern Romania, the population

density over southeastern Romania is lower (70–80

people per kilometer squared) with fewer urban areas,derived from the 2002–03 Moderate Resolution Imaging

Spectroradiometer (MODIS) data at 1-km grid spacing

(Schneider et al. 2003) (Fig. 6b).

The high number of tornadoes over southeastern

Romania can be attributed to the mesoscale environ-ments over this region that are more favorable for tor-

nadoes compared with other regions. Brooks et al.

(2003b) used the National Centers for Environmental

Prediction–National Center for Atmospheric Research

(NCEP–NCAR) global reanalysis dataset (Kalnay et al.

1996) for the years between 1997 and 1999 to obtain

vertical profiles that resemble radiosonde profiles (Lee2002). The profiles were used as proximity soundings to

develop relationships between the environmental vari-

ables (e.g., CAPE, 0–6-kmshear,0–1-kmshear,and2–4-km

lapse rate) and severe convective storms in the United

States. These relationships were then applied to make

estimates of the distribution of favorable severe con-

vective storms and tornado environments over Europe.

For Romania, the average number of days with favor-

able tornado environments is between 4.5 and 6.0 over

southeastern Romania and is lower than 3.0 days over

most of Romania (Fig. 16 in Brooks et al. 2003b, p. 89).

Thus, the results from the present study are consistentwith the results obtained by Brooks et al. (2003b) for the

distribution of favorable tornado environments over

Romania.

4. Monthly distribution

From the 126 tornadoes reported in Romania be-

tween 1822 and 2013 containing information on the oc-

currence month, 125 tornadoes were reported between

March and September and one tornado was reported

FIG. 5. Number of tornado reports during the historical period

(1822–1944) (light gray, bar chart), the socialist period (1945–89)(dark gray, bar chart), and the recent period (1990–2013) (solidline) based on estimated intensity on the F scale.



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FIG. 6. (a) KDE analysis for the tornado reports in the recent dataset (1990–2013) showing

the annual average number of tornado reports [(105 km2)21 yr21, shaded according to thescale]. (b) Population density of Romanian counties (people per km2, shaded according to thescale) and the urban areas (blue) derived from the 2002–03 MODIS data at 1-km resolution(Schneider et al. 2003).



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during wintertime on 24 January 2006. The tornadoes

occurred on 110 tornado days, defined as the days in

which at least one tornado was reported. The earliest

start of the tornado season in Romania occurred on 29

March 2006, when a tornado was reported over Târgu-Jiu (southern Romania; Fig. 2), and the latest end of the

tornado season occurred on 23 September 1913, when

a tornado was reported over Tuzla (eastern Romania;

Fig. 2). The majority of tornadoes have been observed

during May–July, when 98 tornadoes (77.8% of the re-

ports containing information on the occurrence month)

were reported in 83 days (75.5% of the tornado days)(Fig. 7). The peak month for tornado reports is May,

with 36 reports representing 28.6% of the reports con-

taining information on the occurrence month. The large

number of tornado reports includes a tornado outbreak

from 7 May 2005, when eight tornadoes were reported

over southeastern Romania. The peak month for tor-

nado days is June with 31 days representing 28.2% of all

tornado days (Fig. 7).

As in Romania, tornadoes in the neighboring coun-

tries occur most frequently between May and August,

with a peak in late spring or early summer (May–June)

[Szilárd (2007) for Hungary; Simeonov et al. (2013) forBulgaria]. The peak occurs later in the summer (July–

August) over western Europe [Holzer (2001) for Aus-

tria; Dotzek (2001) for Germany; Paul (2001) for

France] and northern Europe [Tooming (2002) for Es-

tonia; Marcinoniene (2003) for Lithuania; Rauhala et al.

(2012) for Finland; Peterson (2000) for Sweden; Holden

and Wright (2004) for the United Kingdom; Tyrrell

(2003) for Ireland]. For southern Europe, the peak oc-

curs in late summer and autumn (August–October)

[Gayà (2011) for Spain; Leitão (2003) for Portugal;

Giaiotti et al. (2007) for Italy; Matsangouras et al. (2014)

for Greece].

5. Diurnal distribution

The diurnal distribution of tornadoes in Romania into

2-h bins in local time (LT 5 UTC 1 2 h), is shown in

Fig. 8. The diurnal distribution is based on 95 tornado

reports (75.4% of all reports) between 1822 and 2013

that contained information on the occurrence time. The

majority of tornadoes (88 reports, 92.6% of all cases)were reported between 0900 and 2059 LT, with a peak in

the afternoon between 1500 and 1659 LT (28 reports,

29.4% of all cases). The reporting of only seven torna-

does between 2100 and 0859 LT may be because of the

difficulties associated with spotting tornadoes at night

(sunset is approximately at 2100 LT during June–

August) or because they occur when the public tends to

be asleep (Ashley et al. 2008). The diurnal distribution of

tornado reports in Romania is similar to those observed

in the neighboring countries. For Bulgaria, Simeonov

et al. (2013) showed that tornadoes tend to occur be-

tween 1400 and 1800 LT (80% of all reports) with a peakaround 1600 LT. Tornadoes in Hungary occur most

frequently between 1500 and 1900 LT (72% of all re-

ports) (Szilárd 2007).

6. Conclusions

This study summarizes the tornado climatology of

Romania between 1822 and 2013 based on a dataset

comprising 129 tornadoes reported on 112 days. The

tornado climatology was divided into three periods:

FIG. 7. Thepercentage of the annualtotal of tornado reports (barchart) and tornado days (solid line) occurring in each month be-tween 1822 and 2013.

FIG. 8. The percentage of the daily total of tornado reports be-

tween 1822 and 2013 occurring in 2-h bins starting at the indicatedlocal time (e.g., 1500 LT indicates the period between 1500 and1659 LT).



11/13

(i) the historical period (1822–1944) during which 33

tornadoes were reported, (ii) the socialist period (1945–

89) containing only 7 reports, and (iii) the recent period

(1990–2013) with 89 tornado reports. The increase in the

number of reports during the recent period can be at-

tributed to increased public awareness (e.g., after the

Fac

aeni F3

1tornado from 2002, or due to movies anddocumentary reality television series on tornadoes), in-

creased access to information and communication

technology (e.g., mobile phones, Internet), and volun-

teer severe weather spotters. The main conclusions of

the study are as follow.

1) The spatial distribution of tornado reports shows that

tornadoes are more frequently reported over eastern

Romania, with a maximum over southeastern Ro-

mania [approximately 1.5–2.25 (105 km2)21 every

5 yr]. We speculate that the large number of torna-

does over southeastern Romania can be attributed to

the mesoscale environments over this region that aremore favorable for tornadoes compared with other

regions of the country, but further studies are neces-

sary to confirm this hypothesis.

2) The distribution of tornado reports on the F scale

shows that the historical dataset is dominated by

significant tornadoes (F2 or F3) (12 of 23 reports for

which an estimation of the intensity was possible).

This bias toward significant tornadoes can be ex-plained by the fact that strong tornadoes have a large

impact on society and thus are reported more

frequently compared with weak tornadoes (F0 and

F1). With a more efficient collection of tornado

reports and an increased level of awareness among

the public, the recent dataset is dominated by weak

tornadoes (38 of 41 reports for which an estimation of

the intensity was possible).

3) The monthly distribution of the 126 tornado reports

containing information about the occurrence month

shows that tornadoes are reported more frequently

in May–July (98 reports), with a peak in May (36

reports).

4) The majority of tornadoes were reported between

0900 and 2059 LT (88 of the 95 tornado reportscontaining information about the occurrence time)

with their peak between 1500 and 1659 LT (28 reports).

The Romanian tornado database developed in this

study represents a contribution toward a pan-European

tornado database that will provide the basis for better

understanding the tornado threat in Europe.

Acknowledgments. We thank David M. Schultz from

the University of Manchester for his helpful suggestions

and advice on many aspects of this research and on

improving the manuscript. This work was initiated when

both authors were at the Romanian National Meteoro-

logical Administration, and we thank all our colleagues

in the Laboratory of Nowcasting Techniques and Severe

Weather Forecasting for their contributions to the de-

velopment of the Romanian tornado database. We also

thank Editor Pam Heinselman and anonymous re-viewers for their comments that improved our article.

Partial funding for BA comes from Grant NE/H008225/1

from the U.K. Natural Environment Research Council

(NERC) to the Tropopause Folding, Stratospheric In-

trusions and Deep Convection (TROSIAD) project at

the University of Manchester and from an AXA Re-

search Fund postdoctoral grant.

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Tornadoes in Romania

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