Convective activity over Croatia, presented in this case study, was only a part of
a large heavy convection event in the central Europe which happened from 21st to 23rd June. The whole
course of development and the onset of the convective events is discussed in detail with help of the relevant NWP parameters for
the entire process over central Europe.
The investigation of processes over Croatia is focused on the convection within the cold front, convection at the leading edge of the front induced
by orography combined with a strong SW flow and strong instability.
The following theories can describe convection within and in front of the cold front :
To get better insight in convective processes and convective weather features it is preferable to study also the chapter Cumulonimbus (Cb) and Mesoscale Convective System (MCS) from the "Manual of Synoptic Satellite Meteorology".
Development of the big convective cells within the cold front follows closely the course of classical development described in this conceptual model. Development at the leading edge of the front can be followed by satellite loop and radar data over Croatia.
Situation typical for the thickness ridge, ahead of the cold front. The moist warm air is advected from the south or south-west which, together with the drier and colder air in the upper levels, leads to potentially unstable stratification of the troposphere. Severe convection at the windward (Rab island) and leeward (north-east Croatia) side of the orography, ahead of the front, during the night of the 22nd June can be followed.
Convection is enhanced through a combination of potential instability (confirmed by the numerical field of Showalter index, radio sounding and radar data) and frontal and pre-frontal convergence.