Synoptic situation in the European territory of Russia (ETR) at the end of the first decade of May was determined by interaction of an inactive area of low pressure over the Norwegian Sea and of the area of high pressure with the center over western Kazakhstan. Between these centers of atmospheric action over the western Russian plains from the south-west to north-east stretches high-rise frontal zone along which the active wave cyclones were moving. The trajectories of these cyclones were lined along the southern and eastern coast of the Baltic Sea so that the center of ETR was in their warm sector. Throughout the troposphere above the center of the ETR dominated southern and south-western streams bringing warm and relatively dry air from the North Caucasus and Lower Volga to the Moscow.
Synoptic conditions on May 9 in Moscow region were defined by the warm sector of the wavelike cyclone. Center of the cyclone at 4:00 Moscow time, was in the Pskov area and was shifting to the north-east at a speed of 40 km/h. Caused by the cyclone cold front was passing through the territory of Smolensk and Tver regions in 300-350 km west of Moscow.
In Moscow and the Moscow region in the morning of May 9 the weather was almost without clouds. Temperature in the city was 10-12 ° C and a relative humidity of 65-70% with a weak south wind of 2-4 m / s.
Flight works on modification of clouds to improve weather in Moscow May 9, 2014 during the celebration of Victory Day were started in accordance with the Plan of Flight Operations agreed with the customer — at 4.18am from the airport «Ostafievo» in the air was raised plane meteolaboratory Yak-42 «RosHydromet» for atmospheric sounding, cloud monitoring of the situation in the Moscow region and carrying out, works if necessary, with liquid nitrogen and pyrotechnical with silver iodide.
According to the radar observation after the vertical sounding of the atmosphere the aircraft was instructed to conduct reconnaissance of meteorological situation in the west — north-western sector (azimuth 200 — 340 degrees) at the distance of 250-270 km from Moscow. According to visual observations from aircraft near Tver observed cloudiness of 6-7 points.
Bearing in mind the information from the board of the meteolaboratory and data radar observations (Fig. 1) The Customer has decided to launch another airplane along with the research aircraft. In this regard at 06.30am an An-12 was raised from the airdrome.
Considering a chance of the airmass developing of the clouds in the afternoon 2 aircrafts were in the air at the same time
By 6pm it became clear that the airmass cloud development is nor happening (Fig. 3) so the Command Post instructed to return Yak-42 «RosHydromet» and leave only An-12 to keep monitoring of meteo-situation.
At 9pm as directed by the customer the works on the meteo protection of Moscow were accomplished.
Precipitation in Moscow May 9, 2014 were not observed.