Synoptic situation over the central area of ​​the European part of Russia (EPR ) on May 9, 2013 was formed by the north- eastern periphery of the vast high-altitude anticyclone with its center located to the west of Kiev-city and its ground-level center located to the south of Moscow in the Kursk area . To the west of Smolensk-city the warm atmospheric front was moving to the east toward Moscow.
The atmosphere was stably stratified . The zero isotherm was located at an altitude of 2,900 meters , the tropopause — at an altitude of 11,500 m. In the lower ground level there was a weak north- east wind,  in the middle and upper troposphere was dominated by north- west wind 7-20 m/s amplifiing up to 30-38 m / s closer to the tropopause .
In the morning of May,9 in Moscow and surroundings it was low-cloudy (1-3 b Cs — Ac) with the temperature near the ground was 9 — 11оС , relative humidity 65-70 % and weak east ground  wind.
The pressure has been slightly inclreasing during the day. The air in the grounf layer warmed up to 23 оС. The cloud system of the warm front moving from the west was formed by incomplete upper and middle and small cumulus clouds at 2500m. More dense clouds were located in the area of Novgorod- Pskov. The area within a radius of 500 km from Moscow was rain-free.
At 4am the meteo-aircraft An-12 number 68 took off from the airport ‘Chkalov’ for vertical-horizontal sounding of the atmosphere and clouds , visual monitoring of the evolution of clouds for timely detection and destruction the developing cumulonimbus cells. At 10am minutes it was replaced by another aircraft  An-12 number 14 , and in 4.01 pm it was in it’s turn replaced by a third plane An-12 number 29. Planes were performing the  monitoring of the atmosphere and clouds. Active effects were not carried out. At 6pm as directed by the General customer aerial work was finished.