Moscow and surrounding regions were severely hit by intense snowfall in early February 2018.
By Larisa Nikitina, Aviamettelecom of ROSHYDROMET, and Vesa Nietosvaara, EUMETSAT
Strong and prolonged precipitation took place in Moscow and surrounding areas over the weekend of 3 and 4 February.
The event had been building up couple of days earlier, when an active cyclone from the Mediterranean area merged with a cyclone from the Atlantic, bringing lots of moisture into western parts of Russia. Figure 1 shows this situation on 3–4 February.
The strong Siberian winter anticyclone slowed down the movement of the low pressure centre, resulting in prolonged precipitation over the region for nearly three days. The Moscow metropolitan area was severely affected by the precipitation, which turned from freezing rain and wet snow on Saturday, into full-blown blizzards on Sunday and Monday.
Figure 2: Meteosat-8 Airmass animation, 3 February 13:00 UTC–5 February 06:00 UTC. Download animation (MP4, 6 MB)
The Meteosat-8 Airmass imagery, 3 February 13:00 UTC–5 February 06:00 UTC (Figure 2) shows the development of the system between 3 and 5 February. The satellite image is overlaid by ECMWF 0…12 h forecasts: isobars (black solid isolines), 2 m temperature (blue solid and dashed isolines) and 10 m wind (red). The location of Moscow centre is marked with a red X
The extensive and thick frontal clouds congesting over and around Moscow region during 3 and 4 February can be clearly seen on the animation. The thickest clouds can be seen over Moscow in the early hours of Sunday 4 February.
At noon on 4 February the heaviest rain bands passed Moscow, and the colder airmass replaced the warm airmass. This can also be seen as an intrusion of a very dry airmass, seen as a striking red stripe over the Moscow region, around midday.
The temperature gradient near surface also intensified, and at the rear of the cyclone the strong cold air advection streamed over the whole region, leading to a rapid drop in the surface temperature and high and gusty northerly winds.
On left: location of the VCS. On right: Equivalent Potential Temperature (black solid lines) and Potential Vorticity (solid magenta lines).
On left: location of the VCS. On right: Equivalent Potential Temperature (black solid lines) and Temperature (dashed blue and solid red lines).
This strong frontal structure is also well seen in the Vertical Cross Section taken through the system on 4 February 00:00 UTC (Figure 3 and 4). In the north the dynamic troposphere indicated by the PV=2 isoline is very low, only 500 hPa, while in the south the troposphere is around 250 hPa. The frontal layer indicated by tight Equivalent Potential Temperature gradient zone extends throughout the troposphere (Figure 3). Temperature gradient (Figure 4) is strong across the front near the surface.
Temperature differences across the frontal zone were particularly intense: the mild temperatures on Saturday were quickly replaced by freezing temperatures, down to -12 °C by Sunday. These quickly varying temperature conditions, combined with intense prolonged precipitation, caused adverse weather conditions — freezing rain and wet snow on wires and trees, slippery conditions on streets and roads, together with high snow accumulations.
In total more than 50 mm of precipitation fell in Moscow from Saturday to Monday night, which is more than the monthly norm for snowfall (36 mm of precipitation for February).
The Russian Ministry of Emergency Situations confirmed that 2,000 trees fell overnight in the Russian capital. At least one person died and five were injured. More than 150 flights at the four Moscow airports were either cancelled or postponed.
Tens of thousands of people were left without electricity in the Kaluga, Vladimir, Tula, Smolensk, Bryansk, Tatarstan, Penza and Saratov regions.