Showalter Index

The showalter index gives a good indication of the areas where convective development may be expected. Minimum values (-3 or less, as a signal for highly unstable area) are found in the area with cloudiness connected to the cold front.

6 hours later, the frontal cloudiness still corresponds to the Showalter index minimum. Also, the values under -1 can be observed over eastern Turkey indicating the unstable atmosphere and the location of the expected convective development (this area is connected with an upper level low which can be observed at WV 6.2 satellite images and at geopotential height 300 hPa).

The atmosphere in the frontal area is very unstable with the Showalter index less then -3. High potential instability of the atmosphere is found over eastern Turkey as well.
 

The level of convective development decreases as the frontal zone reaches the area of the positive Showalter index. The negative values behind the front and over eastern Turkey indicate an unstable atmosphere.

As the sun rises the atmosphere over the inland becomes more unstable again. The three systems develop and in the satellite image numerous convective cells and MCSs are recognised.

The biggest part of Turkey is still unstable with values of the Showalter index under -1.

The atmosphere has stabilized and most of the convection died out over the past few hours. The area over eastern Turkey is still highly unstable with the Showalter index under -1, at the Black sea coast even -3.

The Showalter index over western Turkey shows values highly above 0 which makes the occurrence of thunderstorms unlikely. The area over eastern Turkey is still unstable with the Showalter index under -1. Despite of that, the convection is not intensifying anymore, showing that the Showalter index is should not be taken as the only indication for the occurence of convective development.