The area of the Municipality of Ajdovščina is highly exposed to strong wind, called bora, which occurs 42 days per year on average. Its strongest gusts exceed the speed of 200 km/h. Bora affects people’s everyday lives, causes damage in agriculture, traffic and destroys buildings.
In the periods of extremely strong wind people are advised not to leave the buildings due to the safety reasons. Kindergartens, schools, other public buildings, factories and even medical center are closed. Furthermore, strong wind easily tears down the electricity and telephone cables. Lack of the electrical power affects also the supply of the drinkable water. Inevitable bora’s consequences are smaller or bigger damages on the buildings, most common consequences are uncovered roofs.
When the wind speed exceeds 100 km/h the traffic is obstructed. The highway is closed for the truck trailers because of the risk of overturning, which brings negative consequences on the local economy. The Municipality of Ajdovščina is known for its agriculture, which gives jobs to several inhabitants in the area. Bora constantly poses threat to the agriculture; it can break or uproot the trees and crops and dries the soil. Damage in agriculture most likely occurs in the spring, when bora shakes off the tree blossoms, hence, destroys the crops. Moreover, due to its strength it accumulates or deflates the soil, consequently farming is impeded.
Regardless of its mild climate conditions, Split, its surroundings and the whole Dalmatia County occasionally suffers from strong winds, gusty winds or other kinds of troublesome winds. In some weather conditions the effects of wind can cause interruption of transportation on air, land and sea: airports are closed because of the hazard of wind impact on airplanes which are endangered during landing and take-off. Parts of roads are sometimes closed to avoid danger of wind force impact on vehicles. This is especially applicable to bridges, where side impact of wind is very dangerous. Ferry lines are interrupted on the sea in case of high waves. Variations in wind direction and gust with relation to terrain configuration, like gorges, can cause danger with high intensity.
In latest years, as a result of global warming, besides winds, whirlwinds occur more regularly in Dalmatia. This kind of circular wind can damage property, agricultural crops and can even cause casualties. Real time monitoring of wind conditions, prediction of danger and proper reaction can decrease the cost of damage the wind is causing.
The winter storm Kyrill hit Western Europe in general and the City of Dortmund in particular between 17 and 19 January 2007. Maximum wind guests reached 202 km/h in the southern parts of the City.
Kyrill, like many other strong European winter storms, was embedded in a pre-existing, anomalously wide, north-south mean sea-level pressure (MSLP) gradient field. In addition to the range of gusts that might be expected from the synoptic-scale pressure field, mesoscale features associated with convective overturning at the cold front are suggested as the likely causes for the extremely damaging peak gusts observed at many lowland stations including Dortmund during the passage of Kyrill’s cold front. Compared to other storms, Dortmund was affected by, Kyrill was by far not the most intense system in terms of core pressure and circulation anomaly. However, the system moved into a pre-existing strong MSLP gradient located over Central Europe which extended into Eastern Europe. This fact is considered determinant for the anomalously large area affected by Kyrill.
Additionally, considerations of windiness in climate change simulations using two state-of-the-art regional climate models driven by ECHAM5 indicate that not only Central, but also Eastern Central Europe may be affected by higher surface wind speeds at the end of the 21st century. These changes are partially associated with the increased pressure gradient over Europe which is identified in the ECHAM5 simulations. Thus, with respect to the area affected, as well as to the synoptic and mesoscale storm features, it is proposed that Kyrill may serve as an interesting study case to assess future storm impacts and plan necessary response actions.
Here, main fields of action are:
- An adapted forest management strategy including the cultivation of more wind-resistant tree species.
- A continuous check of the structural stability of alley trees
- Investments in technical response capacity of the fire brigade