Nedim Sladić on climate change in BiH: Bosnian storm chasers predict disasters

Nedim Sladić (18) is a first-year student of Software Engineering at the International University of Sarajevo. He is a polyglot and an enthusiast of meteorology and climatology.

Kristijan Vujčić is a third-year student of Public Administration and lives in Prijedor. He is an enthusiast of meteorology and climatology, just like Nedim.

PATRIA: Bosnia Storm Chasers, a community of storm chasers, was founded in 2014, after the warmest January and February in recorded history, followed by tragic floods in May and then in August. What was your formation process like in practice?

SLADIĆ: The collaboration with Kristijan Vujčić began in mid-2013. We met by chance through the Croatian website “Crometeo“, which also gathers storm and meteorology enthusiasts, and that's how we started our first plans. I only remember that one night we mentioned the topic of thunderstorms, and it was as if a light bulb suddenly turned on above our heads, and we started thinking about the extremes that could soon affect Bosnia and Herzegovina and our neighborhood.

The agreement, which was the first alarm signal, came at the beginning of 2014. We witnessed January starting with very strange weather, as it was constantly atypically warm and sunny, and everything resembled April.

Kristijan and I, who already have prior knowledge in climatology and meteorology, constantly monitored the prognostic models, which are based on calculations and synoptics. During that period, they were giving extremely illogical calculations until the end of February. We knew something was wrong when the temperature in mid-February often went above 20°C and when we saw that everything was already in the phase of blooming and budding. That was the second alarm signal.

Kristijan Vujčić 

The third and our final signal came in the fateful May of 2014. We noticed a very strange behavior of a cyclone that, due to the atypically warm winter and warm ground surface, reacted violently, and that's where the illogicality arose. Namely, when the cyclone entered the Adriatic Sea, it was very weakened and did not give any significant signal for precipitation. However, as it moved east towards Bulgaria, its center was at that moment over the Black Sea, where it further enriched itself with moisture and heat. Instead of continuing eastward, where it would eventually dissipate, it made a retrograde movement and again affected the areas of Serbia and Bosnia and Herzegovina, where it lingered for a longer period, thus creating a very strong weather change that caused unprecedented floods in the central, eastern, and northern parts of Bosnia, causing significant material damage as well as loss of life, even around twenty-eight, although it is believed there were more.

But you know how it is, in nature everything has an exception – “Nulla regula sine exceptione.”

At that point, we officially said: “We can't wait any longer, the year has started too turbulent, I don't think we're too late yet and that this will continue, our time is starting now!“

PATRIA: You recently predicted that northeastern Bosnia would be under snow, even up to 36 to 42 centimeters. How? On what basis do you arrive at such accurate forecasts?

SLADIĆ: Although all relevant and available data indicated the formation of heavy snowfall in the north of Bosnia and especially in Croatia, neither Kristijan nor I relied on them. We waited to see how the prognostic models (ensembles) would behave, which, through synoptics and calculations, help us to see how much precipitation we can expect over an area on that day, the average wind speed, the expected snow depth, as well as many other parameters crucial for what we do. But certain parameters we observed for this case gave the green light for heavier snowfall, primarily in the north of Bosnia, and somewhat less in its central part. And that's how it happened.

This is how we monitor the weather every time, and based on these prognostic models, we arrive at precise forecasts.

It is important to mention that the current snow depth, which has reached almost 50 cm in northern Bosnia these days, will melt very rapidly, and an increase in water levels is expected in the coming period at all measuring stations, but this will be far from any concern for possible floods.

PATRIA: Let's give people the forecast for the coming days right away, so they can start following your page “Storm Chasers” with confidence starting today.

SLADIĆ: The forecast for the next few days indicates an increase in air temperature values, both morning and daytime. As we approach the end of the weekend, a more humid air mass will flow in from Western Europe, which, as part of the Genoa cyclone, will bring slightly larger amounts of precipitation to the southern and southwestern parts of Herzegovina, while Bosnia will be significantly drier, but not completely dry.

Precipitation in the form of rain is expected in the area of Bosnia, and precipitation values will range from 1 to 9 liters of rain per square meter, while in Herzegovina, these values on the weekend will be between 9 and 27 liters per square meter.

As we move towards Monday, there will be a drop in atmospheric pressure, so we expect a larger difference in atmospheric pressure between the north and south of the country, which will cause moderate to strong southerly and southeasterly winds, with possible storm-force gusts in Herzegovina.

At higher altitudes, warmer air will flow in, which, in a strong southerly current, will cause an increase in air temperatures that will reach the limit of 18°C on Sunday and Monday.

PATRIA: How far in advance can you predict the weather? Storms are becoming more sudden, stronger, and more extreme.

SLADIĆ: A precise forecast with a probability of occurrence of 55 to 60% can be given up to the fifth day. The most reliable forecasts are given up to three days, when the probability of occurrence is around 80%. Beyond the fifth day, we have reached the limit, like in mathematics, which we cannot solve further - we can only guess what will happen next and draw deductive conclusions that often end up being wrong predictions. That's why we strictly focus on forecasts up to five days. In case we see something coming that could be of a larger scale, we issue an unofficial forecast that we constantly monitor and promptly publish all possible scenarios on my 'Nedimov Facebook' profile that at that moment point to certain weather phenomena that are potential in the upcoming period.

And of course, we strive to make our forecasts accurate, clear, precise, and explained in detail, so that a certain group of people who follow us can understand them.

The weather situation is like a moment when you seize a favorable wind for sailing. A northerly, southerly, or tramontana wind will certainly not suit you, but if you catch a calm or a gentle refreshing maestral, a westerly wind, that's the moment you must make the most of. That's the case with us. A suitable corresponding cloud shapes the intensity of the storm. The storm has its direction and its path, but in such cases, luck plays the biggest role.

Storms, as we have noticed, have been getting stronger and stronger in recent years, and this trend will continue.

From 2008 to the present day, we have recorded phenomena in Bosnia and Herzegovina that we couldn't see before. That is the phenomenon of tornadoes. One such tornado occurred twice in Lijevče polje and in Popovo polje, one near Banja Luka airport Mahovljani, one near Prijedor, and one on Lake Modrac.

We observe here how some unusual phenomena are occurring in our country, and that is a corpus delicti that the weather is becoming more and more dynamic, and the extremes are getting bigger and bigger.

We observe that we have increasingly longer, warmer, and drier summers, as well as shorter and shorter winters, which are often without significant snow cover, and without sharp frosts that used to drop to -23°C, excluding 2012.

These frosts in the early 2000s regularly and consecutively appeared every winter, starting from 2000 to 2006, at least two or three times either in January, February, or even in March in 2005. Then, after the extremely warm winter of 2007, they disappeared, and in the following years until 2012, they did not drop below -16°C. We also notice sudden shifts between warm and cold periods. We hardly have summers anymore where the temperature approaches or exceeds 37°C for at least one day (exceptions were only 2005 and 2014, which were very mild during the summer). Sudden changes in precipitation amounts are also evident. This can be best illustrated by the example that we ended 2014 as the rainiest year ever, while on the other hand, we ended 2015 as a very dry year, which brought a precipitation deficit of up to 200 liters below the average annual total precipitation.

PATRIA: Do you have any information about climate change specifically for our Bosnia and Herzegovina? How threatened are we compared to other European countries, and especially our neighboring countries? Which areas of BiH are most threatened?

SLADIĆ: We have information, but there is very little of it. What we can say publicly is that the average temperature in many parts of Bosnia and Herzegovina has exceeded 1°C in the last fifty years in some places, which is of course considered worrying.

The precipitation amounts recorded throughout the country show a slight deficit. For example, Sarajevo, according to the long-term average (1961-1990), had an average annual precipitation of 932 liters per square meter, while according to the newer long-term average (1981-2010), it has an annual precipitation of 33 liters less, 899 liters of precipitation per square meter.

The trend of precipitation in the city and towards the south of the city (Hadžići, Ilidža) is even up to 108 liters less rain. The annual precipitation at AMS Butmir shows data of 800.1 liters of precipitation per square meter. By deductive reasoning, as we move towards the southwest and south of the city, precipitation decreases. Bosnia and Herzegovina, like other neighboring countries, is not greatly threatened, but it needs to be prepared for all the extremes that will affect us more and more in the coming years.

It is very difficult to pinpoint which areas of Bosnia and Herzegovina are most threatened, given the lack of relevant data.

PATRIA: There are more and more storms attacking agricultural areas and causing terrible damage. Have any agricultural associations or state institutions ever consulted Bosnian storm chasers?

SLADIĆ: Since we are a relatively young community, our time is yet to come. But we hope that the wider public will recognize us, start to believe in us, and that our farmers will eventually negotiate mutual cooperation in the future.

PATRIA: Where will this increasing climate chaos stop? Where there is no order, it is difficult to predict the weather. What can stop these horrors and disasters at all?

SLADIĆ: If we don't respect nature, it won't respect us. By deductive reasoning, we are its greatest enemy. We must take care of what we are doing to our climate.

Meteorology and climatology in Bosnia and Herzegovina are at their limit as sciences, at a critical point – something similar to a corresponding quadratic function that you sketch on a graph and determine its local extremes. That's exactly what we are doing in Bosnia and Herzegovina. We must finally wake up and realize that if we don't react in time, the consequences can be catastrophic. The engagement of all of us and all bodies responsible for informing the public is very important. It is crucial that the public is timely informed with relevant data about all current or upcoming weather conditions and adversities at any time of the day. Meteorology is a science not to be trifled with. Bosnia and Herzegovina has a temperate climate, but the question is how long it will withstand the immense burden of constant shocking changes. I repeat: Cooperation with nature is the most important thing – let's respect nature and it will respect us.