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According to the Hydrometeorological Center, Moscow saw a snow depth of 35 cm on December 19, a level not recorded since 1941. Despite the rarity and perceived anomaly of this snowfall, experts insist it should not be treated as an unprecedented event, notes Marina Makarova, a leading meteorologist with the Russian Hydrometeorological Center.

In meteorology, the term anomaly is used to describe deviations from the normal conditions. The usual snow cover for this period averages about 15 cm, so a depth of 35 cm is more than twice that figure and corresponds to what is typically observed at the height of winter, around January 31 to February 1.

Yes, December brought heavy snow, yet this is not unusual. Last year, for instance, although rainfall was lighter, December still delivered snowdrifts of 23–25 cm by Christmas. February 2021 was exceptionally snowy as well. Such fluctuations are part of normal weather patterns, and researchers remain measured about these variations.

Weather from year to year can swing dramatically: December last year was cold and snowy, while this December has included long stretches of thaw. By comparison, December 2019 featured above-zero temperatures that prevented sustained snow cover, a genuine anomaly in the historical record. That scenario marked the first occurrence of its kind in continuous observations.

For experts, snow height alone does not capture the full picture. Hydrologists and agrometeorologists look closely at the moisture content of the snow—how much water it contains—because that determines the potential for spring floods. Snow density matters too for calculating moisture reserves, but density has not been high recently. Precipitation amounts included 13 mm overnight on December 18 and 12 mm the week prior on December 12, yet none of those days matched the record snowfall seen during isolated events.

When snow falls at very low temperatures, it tends to be exceptionally fluffy. Since December 21, a thaw has begun. The snow will compress, sag under its own weight, and melt. This makes snow depth a relative measure, requiring a calm, informed response to the changing accumulations. Before the latest thaw, the snow cover stood at 20 cm; after the thaw, it dropped to 5 cm, then rose to 34 cm, and now it is expected to fall again. Snow cover shows a complex, evolving pattern all winter as cold periods alternate with melting, precipitation changes, and rain.

December is unlikely to set a new record for total precipitation, though it has almost doubled the 51 mm norm. The most precipitation ever recorded in December occurred in 1874 with 115 mm, followed by December 1981 with 112 mm, as noted by Makarova. Whether January and February will bring similar or heavier snowfalls remains uncertain, since long-range precipitation forecasts are inherently uncertain.

Forecasting precipitation remains challenging because numerical models struggle to capture the spatial and temporal variability of real-world weather. This leads to some forecast errors, especially for extreme events—one might see a heavy downpour in central Moscow while nearby areas remain dry. The complexities stem from the data inputs, including temperature, humidity, wind, ground conditions, and other factors. The quality and resolution of the prediction model, along with how well it represents atmospheric processes and surface interactions, all influence the forecast. A model with 100 percent accuracy for precipitation is not available anywhere on the planet.

There is no claim that Russia has a uniquely superior or inferior forecasting capability. The difficulty of forecasting precipitation, particularly extremes, is a global challenge. Heavy rainfall and snow can have serious socio-economic consequences, from flooding and crop losses to traffic disruption and road accidents. High-quality forecasts of extreme weather are in strong demand because they help protect lives and minimize economic damage.

Forecast accuracy improves when the forecast window is shorter—the most reliable predictions cover the near term. The recent and ongoing snowfall was forecast with a reasonable degree of precision, though mistakes are inevitable in weather science because the atmosphere does not follow a fixed script.

While Moscow has seen substantial snowdrifts, the world has faced even more intense snowfall in recent years. The most notable historical snowfall was the February 1972 snowstorm in Iran, where depths reached eight meters in some areas and more than 4,000 people died. Whole villages were buried, and survivors found themselves unable to escape.

Another major event was the 2008 Afghanistan snowstorm, where January temperatures dropped to minus 30°C and some areas received up to two meters of snow. The phenomenon caused widespread casualties and severe frostbite incidents for those exposed to the cold.

In 1977, Western New York and southern Ontario endured extreme snow with parts of the landscape covered by more than 2.5 meters, accompanied by winds exceeding 100 m/s that produced drifts up to 12 meters. The disruption lasted weeks, straining infrastructure and supply chains, especially for institutions like boarding schools.

The so-called Storm of the Century in March 1993 delivered heavy snow from Canada to Honduras, with up to 130 cm in the mountains and about a meter elsewhere. That event was linked to a large-scale cyclone and a hurricane, claiming numerous lives and affecting a vast region.

Even snowfall that may seem routine by some standards can become a crisis if regions are unprepared. In China, late January 2008 brought as much as 45 cm of snow to otherwise vulnerable areas, halting transport, breaking power lines, and freezing water pipes. The impact extended to rural communities, disrupting food distribution and leaving many residents without essentials for days. In Wuhan, Jingzhou, Yichang and other cities, the cold extended its reach, with consequences that touched public health and daily life. Losses spread across households, agriculture, and infrastructure, highlighting how snow events ripple through society.

Makarova stresses that, even if Moscow does not snow again soon, residents should stay alert to other winter hazards. A period of cold can be followed by warming with stronger winds, bringing rain or sleet, which can create ice and a slippery surface. Pedestrians and drivers alike are advised to exercise caution during such transitional spells, as conditions can shift quickly.