Synoptic Climatology

Bahía Culebra, at Gulf of Papagayo on the north Pacific coast of Costa Rica, is an area of seasonal
upwelling where more intense cooling events may occur during some boreal winter weeks mainly. To study these
extreme cool events, records of nine sea subsurface temperature stations from 1998 to 2010 were analyzed. Five
events associated with extremely cool temperatures in this region were identified from these records and taken
as study cases. Sea temperatures decreased about 8-9oC during these events and occurred while cold fronts were
present in the Caribbean, with strong trade wind conditions over Central America. These strong wind conditions
may have favored the offshore displacement of the sea surface water. The axis of Bahía Culebra runs northeast-
southwest, a condition that favors and triggers cool water events, mainly because the displaced water is replaced
by water from deeper levels. Rev. Biol. Trop. 60 (Suppl. 2): 173-186.

Dalam pelaporan berita cuaca meteorologi, agar penjelasan dan makna sama di seluruh negara, maka dibuat sebuah kesepakatan untuk melaporkan dalam bentuk Sandi / Kode. Berikut ini adalah salah satu dari jenis sandi tersebut. Materi ini lebih cenderung ke dalam pelaporan cuaca permukaan.

Semoga bermanfaat,
Salam,


Richard Mahendra

This study provides evidence of the monsoon record over the past 25 ka from the Kilang Sarai palaeolake
which is located in NW Himalaya in the rain shadow zone of the Indian Summer Monsoon (ISM). The
multi-proxy study by using geomorphology, carbon isotopes, mineral magnetism, clay mineralogy and
elemental chemistry of a 8 m thick laminated lacustrine sediments indicates that the area experienced
fluctuating precipitation conditions during the last 25 ka. The time period between 12 and 5 ka BP can be
regarded as a very wet interval of the Last Glacial to mid Holocene due to a combined effect of ISM and
Westerlies, followed by aridity after 5 ka BP. Tectonic triggers may have caused the development of
terraces and closure of lake. At the millennial time scale, a correlation of precipitation and vegetational
changes between our data and other records from similar geographical settings suggests that Kilang Sarai
basin responded to periods of strengthening in precipitation during the Last Glacial to early Holocene

three climatic variables, namely daily rainfall, maximum and minimum temperature values, for the period of 30 years from 1988 to 2017, were considered for nine observation stations throughout Sudan. Two methods of Aridity Index (AI) were utilized based on monthly/seasonal and annual rainfall and temperature values to obtain the aridity conditions in Sudan during the study period. Furthermore, the main objective of this study is to measure drought aridity in Sudan. Other objectives are to measure monthly/seasonal or annual aridity and humidity conditions over the same area to identify climatic classification for the nine stations, which are included in this study. Finally, to create a map, which represented all drought, aspects to show the most affected areas throughout the study period and to help decision makers in the natural resources sectors. For this reason, two meteorological drought indices were applied based on climatic variables. Thus, the monthly/seasonal Aridity Index was estimated by using Thornthwaite method, and the study area was classified into five categories, namely, Arid conditions (16), are recorded at Atbara and Khartoum around the 30 years, whereas, Semi-arid are observed at Fasher, El Obaied and Kassala during spring, autumn and winter, and Humid conditions (16-31), observed for the same stations in summer. Very humid (128), recorded at Kadogli, Genena and Gadarif during summer seasons. The annual AI was applied by using De Martonne method. Therefore, the results outlined into four categories mainly, Arid (value 5 at Khartoum and Atbara stations, Semi-Arid (values-5) at Fasher and Kassala stations, Sub-Humid (-10) represented by Genena, Obaied and Kosti and Very Humid (values 30 are represented by Kadogli, and Gadarif. These results indicate that drought in the study area has occurred frequently, and it has spreaded quickly southwards.

Atmospheric circulation strongly modulates precipitation patterns throughout the south of Iran. A Characteristics of synoptic types was chosen to investigate their relation to the spatiotemporal distribution of precipitation within the south of Iran. In this study we examined the interannual variability of precipitation in the southern region of Iran and to establish links between the large-scale circulation pattern. In this region, the majority of precipitation occurs during the rainy season from October to May. The present study applied the empirical orthogonal function (EOF) analysis on the monthly precipitation anomaly data obtained from 302 meteorological stations for the 1981–2010 periods. In mostly month, the first mode explains more than 50 % of the total variance of precipitation. Spatiotemporal fluctuation in precipitation over the studied area can be attributed to moisture transport by dynamic factors. This study shows that the position and strength of high pressure over ...

Abstract
Background
One of the natural phenomena which have had considerable impacts on various regions of the
world, including Iran, is “dust storm”. In recent years, this phenomenon has taken on new
dimensions in Iran and has changed from a local problem to a national issue. This study is an
attempt to investigate the formation of the dust storms crossing the Western Iran.
Methodology
To find the sources of the dust storms entering Iran, first we examine three determined dust
paths in the region and their temporal activities, using MODIS satellite images. Then, four
regions were identified as dust sources through soil, land cover and wind data. Finally,
atmospheric analyses are implemented to find synoptic patterns inducing dust storms.
2
Results and discussion
Source 1 has covered the region between the eastern banks of Euphrates and western banks of
Tigris. Source 2 is in desert area of western and south-western Iraq. Finally source 3 is
bounded in eastern and south-eastern deserts of Saudi Arabia called Rub-Al-Khali desert, or
Empty Quarter. Moreover, south-eastern part of Iraq (source 4) was also determined as a
secondary source which thickens the dust masses originating from the above mentioned
sources. The study of synoptic circulations suggests that the dust storms originating from
source 1 are formed due to the intense pressure gradient between the low-pressure system of
Zagros and a high-pressure cell formed on Mediterranean Sea. The dust events in sources 2
and 3 are outcomes of the atmospheric circulations dominant in the cold period of the year in
mid-latitudes.

three climatic variables, namely daily rainfall, maximum and minimum temperature values, for the period of 30 years from 1988 to 2017, were considered for nine observation stations throughout Sudan. Two methods of Aridity Index (AI) were utilized based on monthly/seasonal and annual rainfall and temperature values to obtain the aridity conditions in Sudan during the study period. Furthermore, the main objective of this study is to measure drought aridity in Sudan. Other objectives are to measure monthly/seasonal or annual aridity and humidity conditions over the same area to identify climatic classification for the nine stations, which are included in this study. Finally, to create a map, which represented all drought, aspects to show the most affected areas throughout the study period and to help decision makers in the natural resources sectors. For this reason, two meteorological drought indices were applied based on climatic variables. Thus, the monthly/seasonal Aridity Index was estimated by using Thornthwaite method, and the study area was classified into five categories, namely, Arid conditions (16), are recorded at Atbara and Khartoum around the 30 years, whereas, Semi-arid are observed at Fasher, El Obaied and Kassala during spring, autumn and winter, and Humid conditions (16-31), observed for the same stations in summer. Very humid (128), recorded at Kadogli, Genena and Gadarif during summer seasons. The annual AI was applied by using De Martonne method. Therefore, the results outlined into four categories mainly, Arid (value 5 at Khartoum and Atbara stations, Semi-Arid (values-5) at Fasher and Kassala stations, Sub-Humid (-10) represented by Genena, Obaied and Kosti and Very Humid (values 30 are represented by Kadogli, and Gadarif. These results indicate that drought in the study area has occurred frequently, and it has spreaded quickly southwards.

Due to human activities the temperature conditions in the most populated urban areas differ significantly from those in the natural environment. I chose to study urban areas because ongoing modifications influence the life of people living there. Most people living in urban areas spend most of their time in the urban roof level of the urban boundary layer between the surface and the average level of roofs therefore the conditions in this layer influence their health. Apart from feeling comfortable the forming heat excess affects energy demands which are in connection with cooling demand in warmer and the heating demand in colder periods. Moreover, it determines biodiversity and the distribution of pollutants and diseases in urban areas.
This study focuses on a small and a medium sized town, Beregszász and Debrecen. Although heat islands are studied in large cities worldwide urbanisation, transformation of built-up areas and not deliberate climate modification take place in smaller towns as well. The presented research studies a meso-scale phenomenon and focuses on determining the factors forming the phenomenon in Beregszász. As a result, the first task was to quantify the parameters of the surfaces forming the heat excess found in Beregszász and to analyse their relationship with urban heat island (UHI) on the basis of the results. Apart from these, it is very important to make the spatial structure and process of the heat excess in the town estimatable using models based on empirical relationships. This could be a useful tool for urban development.
In the vicinity of a measurement point located in a given local climate zone the modification of climate elements is caused primarily by modified surface parameters while the size of the heat excess is determined by the dynamic meteorological parameters. Thus to expose the relationship between heat excess developed on a local scale and the meteorological parameters controlling them was set as a goal. Based on the obtained results, my target was to prepare a criteria system with the help of which the time series of the frequency of weather conditions advantageous for the development of urban heat island could be determined.

Droughts and tropical cyclones (TCs) are climatologically common events in the southeastern United States, yet little research has examined the potential for TCs to ameliorate drought impacts. Here, we identify the frequency of TCs that abruptly end drought conditions (i.e., drought busters, or DB) and determine possible influences of coupled ocean–atmosphere teleconnections on the likelihood of a TC-induced DB (TCDB). Using the HURDAT database and Palmer Drought Severity Indexes from 1950 through 2008, we identified every TCDB for thirty-one climate divisions in the southeastern Atlantic United States. We present the spatial patterns of the total number of TCDBs and the percentage of all droughts ended by TCs using choropleth maps. To determine what teleconnections influenced TCDBs, we used logistic regression analysis and included multiple synoptic-scale circulation indexes as predictor variables. In addition, we used a Fisher's exact test to examine the association between the North Atlantic Oscillation (NAO) and TCDBs. We found that up to 41 percent of all droughts and at least 20 percent of droughts in three fourths of the climate divisions were ended by TCDBs. NAO was a significant predictor (p = 0.005) in the logistic regression model (χ2 = 10.91, p = 0.001), and the Fisher's exact test showed a significant association between NAO and TCDBs (p = 0.003). An odds-ratio calculation showed that TCDBs are 5.8 times more likely to occur during a negative NAO phase than a positive NAO phase. Las sequías y los ciclones tropicales (TCs) son eventos climatológicos comunes en el sureste de Estados Unidos, sin embargo, pocas investigaciones han examinado el potencial de los TCs de mejorar los impactos de la sequía. A continuación se identificará la frecuencia de los TCs que abruptamente terminan con las condiciones de sequía (es decir, las sequías intempestivas (drought busters) o DB) y se determinará las posibles influencias del acoplado de teleconexiones oceánico-atmosféricas en la probabilidad de un DB TC-inducido (TCDB). Utilizando la base de datos HURDAT e Índices Palmer de Severidad de Sequías de 1950 al 2008, identificamos cada TCDB en treintaiuna divisiones climáticas en el sureste del Atlántico de Estados Unidos. Presentamos los patrones espaciales del número total de TCDBs y el porcentaje de todas las sequías terminadas por TCs usando mapas de coropletas. Para determinar qué teleconexiones influenciaron los TCDBs utilizamos el análisis de regresión logística e incluimos múltiples índices de circulación a escala sinóptica como variables predictoras. Además, se utilizó un test exacto de Fisher para examinar la asociación entre la Oscilación del Atlántico Norte (NAO) y TCDBs. Hemos encontrado que hasta un 41 por ciento de todas las sequías y al menos un 20 por ciento de las sequías en tres cuartas partes de las divisiones climáticas fueron acabadas por TCDBs. La NAO fue un predictor significativo (p = 0,005) en el modelo de regresión logística (χ2 = 10.91, p = 0,001), y el test exacto de Fisher mostró una asociación significativa entre la NAO y TCDBs (p = 0,003). Un cálculo de razón de posibilidades (odds-ratio) mostró que los TCDBs tienen 5.8 veces más probabilidades de ocurrir durante una fase negativa de la NAO que en una fase positiva.

The aim of this study was to characterize the rhythm of atmospheric systems in the northeast of São Paulo State, Brazil from the frequency of weather systems and types of polar outflows from the winter of 2008 to the fall of 2009. The circulation analysis was performed by the means of daily synoptic analysis of three isobaric levels: surface, 500 and 250 hPa. The results showed that there were 45 frontal passages mostly during one day, controlling 21.9% of the year. The most frequent intervals between two fronts were of 5 to 6 days, ranging from a minimum of 0 (with two fronts in the same day) to 18 days. Extratro-pical systems controlled most of the time (64.9% of year), with the anticyclonic systems acting in 43% of the year and the frontal ones, in 21.9%. The remaining time was controlled by tropical (Atlantic and Continental) systems (35.1%), being 31.8% by the Atlantic system and 3.3% by the Continental one. The period was dominated by oscillatory-type polar outflows (tending t...

Abstract:

This article considers to what extent a long distance walk, and indeed the memory of that walk, may generate a narrative, as investigated by theorists such as Roland Barthes, by virtue of the very things central to the experience of walking in this way. These things include sudden deviations created by unseen contingencies, encounters and subsequent responsive improvisations or simply dynamic shifts in landscape, resulting in pace change or some other alteration of focus. When we speak of, for example, signposting or the cardinal in relation to narrative, to what extent should we take seriously the relationship between terms used in this way and the way in which they are used to provide geographical structure?



Résumé:

Cet article analyse la manière dont une longue marche, puis le souvenir de cette marche, peuvent générer un récit, au sens que donnent à ce terme des théoriciens comme Roland Barthes.et ce à l’aide des caractéristiques propres à l’expérience même d’une marche faite dans cette perspective. Ces caractéristiques incluent par exemple des déviations soudaines crées par des aléas imprévus, des rencontres et toutes sortes d’improvisations auxquelles elles donnent lieu ou tout simplement les changements continuels du paysage qui se traduisent par des changements de rythme ou de focus. Lorsque nous parlons par exemple de signes indicateurs ou de point cardinal en rapport avec le récit, dans quelle mesure devons-nous prendre au sérieux le lien entre de tels mots et la manière dont ils tendent à structurer la géographie ?

This study assesses effects of drought
on agriculture in a changing climate using maize
and cotton. Two Atmosphere-Ocean General
Circulation model (AOGCM) outputs were
downscaled using statistical downscaling model
(SDSM). It revealed that average annual rainfall
will increase by 1.6% and 2.6% for HadCM3 B2a
and A2a scenarios respectively while maximum
temperature will increase by 0.4 degrees c for A2a and
0.9 degrees c for B2a and minimum temperature will
increase by 1.8 degrees c for B2a and 1.9 degrees c for A2a
scenarios.Drought years were identified using
standardized methods and droughts will become
more frequent and severe for A2a than B2a
scenarios relative to baseline (1981-2010).
Upper limits of yield losses for Maize is 100 %
for all scenarios while for cotton 100, 83 and 8%
for baseline, B2a and A2a scenarios respectively.
To mitigate and adapt these adverse impacts
community cooperation in tackling emissions
should be strengthened and important to have
new crop varieties and technologies.

Extratropical cyclone activity over the central Arctic Ocean reaches its peak in summer. Previous research has argued for the existence of two external source regions for cyclones contributing to this summer maximum: the Eurasian continent interior and a narrow band of strong horizontal temperature gradients along the Arctic coastline known as the Arctic frontal zone (AFZ). This study incorporates data from an atmospheric reanalysis and an advanced cyclone detection and tracking algorithm to critically evaluate the relationship between the summer AFZ and cyclone activity in the central Arctic Ocean. Analysis of both individual cyclone tracks and seasonal fields of cyclone characteristics shows that the Arctic coast (and therefore the AFZ) is not a region of cyclogenesis. Rather, the AFZ acts as an intensification area for systems forming over Eurasia. As these systems migrate toward the Arctic Ocean, they experience greater deepening in situations when the AFZ is strong at midtropospheric levels. On a broader scale, intensity of the summer AFZ at midtropospheric levels has a positive correlation with cyclone intensity in the Arctic Ocean during summer, even when controlling for variability in the northern annular mode. Taken as a whole, these findings suggest that the summer AFZ can intensify cyclones that cross the coast into the Arctic Ocean, but focused modeling studies are needed to disentangle the relative importance of the AFZ, large-scale circulation patterns, and topographic controls.

Tropical cyclogenesis is generally considered to occur in regions devoid of baroclinic structures; however, an appreciable number of tropical cyclones (TCs) form in baroclinic environments each year. A global climatology of these baroclinically influenced TC developments is presented in this study. An objective classification strategy is developed that focuses on the characteristics of the environmental state rather than on properties of the vortex, thus allowing for a pointwise “development pathway” classification of reanalysis data. The resulting climatology shows that variability within basins arises primarily as a result of local surface thermal contrasts and the positions of time-mean features on the subtropical tropopause. The pathway analyses are sampled to generate a global climatology of 1948–2010 TC developments classified by baroclinic influence: nonbaroclinic (70%), low-level baroclinic (9%), trough induced (5%), weak tropical transition (11%), and strong tropical transi...

No mês de junho de 2014, a sequência de oito dias de chuvas ininterruptas promoveu uma série de transtornos (inundações, deslizamentos de terra, interdição de estradas) à parte da população dos estados do Rio Grande do Sul, Santa Catarina e Paraná. O trabalho objetiva identificar a ocorrência de eventos acumulados intensos de precipitação na região do alto Uruguai gaúcho, bem como seus mecanismos sinóticos responsáveis por esses acumulados de chuva. Dados diários de precipitação foram acumulados em grupos de cinco dias (pêntadas), perfazendo o total de 73 pêntadas anuais, no decorrer dos 53 anos da série (1961-2014). A aplicação do percentil 99 ao conjunto de dados determinou o valor do acumulado intenso (157,4 mm). Com base nesse valor foram calculadas a Frequência Absoluta, Frequência Relativa e o Tempo de Retorno desses acumulados intensos. Os resultados demonstraram que, dos dez eventos acumulados mais intensos, 70% ocorreram entre as pêntadas 30 e 47. Os eventos dos anos de 201...

Different patterns of pressure systems together with local factors, leads in generation, rising and spread of dust in West of Iran. In this study, to investigate the factors causing the occurrence of dust in Kermanshah province, 132 cases of dust phenomena (code: 06) were selected and analyzed using Kermanshah synoptic station data for the spring and summer seasons in a period of 5 years (2005-2009). The Factor analysis had been implemented and days with higher correlation coefficient extracted, then clustering operation was performed on the data. 4 dust emission patterns were identified and from each pattern, a certain pattern was selected as a representative day. Using GRADS and NCEP data, maps of geopotential heights, wind speed and vorticity advection were produced and analyzed. To identify the source of dust generation, tracing and simulating the path of dust, HYSPLIT model Lagrangian approach of backward trajectory was used. Generally existence of low pressure cells in the central and southern regions of Iran can lead to the convergence and air intake at near ground levels and strong positive vorticity, which result in cyclonic movements in western regions of Iran Including Kermanshah. These results in the transfer of dust from the dry desert areas of Iraq and high speed winds in the lower levels of dust particles in the region has accelerated the transfer rate. Based on the HYSPLIT outputs, major sources of dust generation, were arid zones of Southern Turkey, Iraq deserts, Syria, North East of Saudi Arabia and Kuwait.

A notable characteristic of the summertime Arctic is the existence of a narrow band of strong horizontal temperature gradients spanning the coastlines of Siberia, Alaska, and western Canada that extends through a considerable depth of the troposphere. Past research has associated this summer Arctic Frontal Zone (AFZ) with contrasts in atmospheric heating between the Arctic Ocean and snow-free land, with its regional strength strongly influenced by topography; however, little is known about its variability. In this study, output from the latest generation of global atmospheric reanalyses is used to better constrain and define the summer AFZ, including its spatial and seasonal characteristics. The relative importance of different factors linked to its variability is then evaluated. The AFZ is best expressed in July and is manifested aloft as a separate Arctic jet feature at about 250 hPa. It is clearly associated with differential atmospheric heating, as evidenced by the sharp difference in surface energy balance terms between the Arctic Ocean and land. Furthermore, the AFZ is strongest over the coastline whether observed near the surface or throughout the troposphere. Interannual variations in peak strength of the AFZ are spatially heterogeneous and systematic near the surface (the 2-m level). Spatiotemporal variability is primarily dependent on factors affecting temperature over land, especially variability in cloud cover, surface wind direction, and the timing of the annual snow cover retreat. Local variability in the timing of annual sea ice retreat is also important through its control on temperatures over coastal seas.

Background One of the natural phenomena which have had considerable impacts on various regions of the world, including Iran, is "dust storm". In recent years, this phenomenon has taken on new dimensions in Iran and has changed from a local problem to a national issue. This study is an attempt to investigate the formation of the dust storms crossing the Western Iran. Methodology To find the sources of the dust storms entering Iran, first we examine three determined dust paths in the region and their temporal activities, using MODIS satellite images. Then, four regions were identified as dust sources through soil, land cover and wind data. Finally, atmospheric analyses are implemented to find synoptic patterns inducing dust storms. Results and discussion Source 1 has covered the region between the eastern banks of Euphrates and western banks of Tigris. Source 2 is in desert area of western and south-western Iraq. Finally source 3 is bounded in eastern and south-eastern deser...

No mês de junho de 2014, a sequência de oito dias de chuvas ininterruptas promoveu uma série de transtornos (inundações, deslizamentos de terra, interdição de estradas) à parte da população dos estados do Rio Grande do Sul, Santa Catarina e Paraná. O trabalho objetiva identificar a ocorrência de eventos acumulados intensos de precipitação na região do alto Uruguai gaúcho, bem como seus mecanismos sinóticos responsáveis por esses acumulados de chuva. Dados diários de precipitação foram acumulados em grupos de cinco dias (pêntadas), perfazendo o total de 73 pêntadas anuais, no decorrer dos 53 anos da série (1961-2014). A aplicação do percentil 99 ao conjunto de dados determinou o valor do acumulado intenso (157,4 mm). Com base nesse valor foram calculadas a Frequência Absoluta, Frequência Relativa e o Tempo de Retorno desses acumulados intensos. Os resultados demonstraram que, dos dez eventos acumulados mais intensos, 70% ocorreram entre as pêntadas 30 e 47. Os eventos dos anos de 201...

three climatic variables, namely daily rainfall, maximum and minimum temperature values, for the period of 30 years from 1988 to 2017, were considered for nine observation stations throughout Sudan. Two methods of Aridity Index (AI) were utilized based on monthly/seasonal and annual rainfall and temperature values to obtain the aridity conditions in Sudan during the study period. Furthermore, the main objective of this study is to measure drought aridity in Sudan. Other objectives are to measure monthly/seasonal or annual aridity and humidity conditions over the same area to identify climatic classification for the nine stations, which are included in this study. Finally, to create a map, which represented all drought, aspects to show the most affected areas throughout the study period and to help decision makers in the natural resources sectors. For this reason, two meteorological drought indices were applied based on climatic variables. Thus, the monthly/seasonal Aridity Index was estimated by using Thornthwaite method, and the study area was classified into five categories, namely, Arid conditions (16), are recorded at Atbara and Khartoum around the 30 years, whereas, Semi-arid are observed at Fasher, El Obaied and Kassala during spring, autumn and winter, and Humid conditions (16-31), observed for the same stations in summer. Very humid (128), recorded at Kadogli, Genena and Gadarif during summer seasons. The annual AI was applied by using De Martonne method. Therefore, the results outlined into four categories mainly, Arid (value 5 at Khartoum and Atbara stations, Semi-Arid (values-5) at Fasher and Kassala stations, Sub-Humid (-10) represented by Genena, Obaied and Kosti and Very Humid (values 30 are represented by Kadogli, and Gadarif. These results indicate that drought in the study area has occurred frequently, and it has spreaded quickly southwards.

Snow cover is an important indicator of climate change but constraints on observational data quality can limit interpretation of spatial and temporal variability, especially in mountain areas. This issue was addressed using archived data from the Snow Survey of Great Britain to infer key climate relationships which were then used to reference larger-scale patterns of change. Data analysis using nonlinear (logistic) regression showed average changes in yearly snow cover were strongly related to mean temperature rather than precipitation values. Inferred change shows long-term decline in average
yearly snow cover with greatest declines in some mountain areas, notably in northern England, that can be related to their position on the most temperature-sensitive segment of the logistic curve. Further declines in snow cover were projected in the future: a central ensemble projection from HadRM3 climate model showed average yearly snow
cover predominantly confined to Great Britain mountain areas by the 2050s. However, inter-annual variability means some years can deviate significantly from average snow
cover patterns. Site-based analysis showed this variability has distinctive geographical variations and different influences for mountains compared to adjacent valleys. Comparison of inter-annual variability with Lamb weather-type frequency and North Atlantic Oscillation index shows the influence of large-scale airflow patterns on snow cover duration. Most notable is the role of northwesterly and northerly flows in explaining snowy years on mountains exposed to that direction, compared to influence of easterly flows at lower levels. Future changes will therefore depend on dominant annual/decadal circulation patterns in addition to long-term declines from climate warming.

An examination of the synoptic weather patterns that accompany supercell‐type tornadoes and very large hail events in Turkey reveals that severe convective storms are possible in a wide variety of large‐scale settings. Upper level lows and troughs are responsible for 47% of tornado days and 55% of very large hail days. These are present in the spring and extended warm season, respectively. Mediterranean cyclones of both central and eastern origins, which are very well‐known and frequent wintertime phenomena, make up of almost a quarter of all synoptic patterns. An important severe convective weather producer over Turkey is the African cyclone, or cyclones bringing North African air parcels. Although these are rare, and relatively much less known, 18% of supercell‐type tornadoes and 12% of very large hail cases are associated with these cyclones. A small fraction of the events occur during cyclones coming over Balkans.

... Shawn M. Milrad, Eyad H. Atallah, and John R. Gyakum ... John's, southwest events are synoptically similar to the overall extreme composite and are marked by a strong cyclone that develops in the Gulf of Mexico, while west events are characterized by a weak Alberta clipper ...